Codex 3265, 3260, 3261, 3266 Reference Manual

Contents

326X Series Modem Reference Guide

Chapter 1. AT Commands

A T, A T& and A T

Selecting Options and Settings ................................................................. 1-8

ATD (Dialing an Unstored Telephone Number) ........................................... 1-10

A TDS, AT

ATE (Asynchronous Echo) ........................................................................... 1-11

ATH (Busy Out Test) .................................................................................... 1-11

ATL (Speaker Volume) ................................................................................. 1-11

ATM (Speaker Control)................................................................................. 1-12

ATO1 (Retrain) ............................................................................................. 1-12

ATP, ATT, AT

ATQ (Result Codes) ...................................................................................... 1-13

ATS (S-Register)............................................................................................ 1-14

ATT (Dial Type) ............................................................................................ 1-14

ATV (Result Code Format) ........................................................................... 1-14

ATX (Call Progress) ..................................................................................... 1-15

ATY (Longspace Disconnect) ...................................................................... 1-18

ATZ (Selecting an Option Set) ...................................................................... 1-18

AT& Commands ........................................................................................... 1-19

AT&C (DCD Control) ................................................................................... 1-19

AT&D (DTR Control) .................................................................................. 1-20

AT&F (Reinitialize Memory)........................................................................ 1-22

AT&G (Guard Tone) ..................................................................................... 1-22

AT&I (Display Modem ID) .......................................................................... 1-23

AT&J (Dial Line Jack Types) ........................................................................ 1-24

AT&L (Line Type) ........................................................................................ 1-25

AT&M (AT Data Format) ............................................................................. 1-26

AT&P (Pulse Cycle) ...................................................................................... 1-27

A T&R, AT
A T&S, AT

AT&T (Test) .................................................................................................. 1-30

AT&T4, AT&T5 (Accept RDL) .................................................................... 1-31

A T&V, AT

Operating Status Messages ....................................................................... 1-32

DTE Rate/Status Summary ...................................................................... 1-34

Error-Correction and Data-Compression Status........................................ 1-35

Transmit and Receive Throughput and Link Utilization Status Display .. 1-36

EIA/TIA 232-D (CCITT V.24) Signal Status ............................................... 1-37

Status Summary Line ............................................................................... 1-38

Display Modem ID ................................................................................... 1-41

CQMS Parameter Status ........................................................................... 1-41

AT&W (Save Changes: Creating New Option Sets)..................................... 1-45

AT&X (Clock) .............................................................................................. 1-47

AT&Y (Power Up in Option Set) ................................................................. 1-47

*

*

*

*

Command Descriptions ................................................. 1-5

*

DS (Dialing a Stored Telephone Number) ............................... 1-10

PT (Dial Type) ..................................................................... 1-13

*

CT (CTS Control) .................................................................... 1-28

MR (DSR Control) ................................................................... 1-29

ST (Modem Status Display)...................................................... 1-31

v

Contents (continued)

Chapter 1. AT Commands (Continued)

A T&Z, AT

Commands ........................................................................................... 1-49

AT

*

AA (Answer) ........................................................................................ 1-49

AT

*

AP (Adaptive Rate) .............................................................................. 1-50

AT

*

AS (Answer in Restoral) ...................................................................... 1-51

AT

*

AY (Auto Type) .................................................................................... 1-52

AT

*

BD (Blind Dial) .................................................................................... 1-52

AT

*

BK (Break Handling) ........................................................................... 1-53

AT

*

CA (Answer/Originate Mode)............................................................... 1-53

AT

*

CD (DCD Loss Disconnect).................................................................. 1-54

AT

*

CM (Connect Message)......................................................................... 1-54

AT

*

CN, AT&Z (Entering Telephone Numbers) ......................................... 1-54

AT

*

CT , AT&R (C, TS) ................................................................................ 1-54

AT

*

DA (Default Dialing) ............................................................................ 1-55

AT

*

DB (Buffer Delay) ................................................................................ 1-56

AT

*

DC (Data Compression) ....................................................................... 1-57

AT

*

DD (Dial Wait) ..................................................................................... 1-57

AT

*

DE (DTE Rate)...................................................................................... 1-58

AT

*

DF (Data Format) ................................................................................. 1-59

AT

*

DI (Leased to Dial Option) ................................................................... 1-59

AT

*

DL (RTS/CTS Delay) ........................................................................... 1-60

AT

*

DP (Pause Delay) ................................................................................. 1-60

AT

*

DR (Auto Redial) ................................................................................. 1-61

AT

*

DS, ATDS (Dial a Stored Telephone Number) ..................................... 1-61

AT

*

DT (DTR Delay) .................................................................................. 1-61

AT

*

EC (Error Correction) ........................................................................... 1-62

AT

*

FC (Fast Call)........................................................................................ 1-63

AT

*

FL (Flow Control) ................................................................................ 1-64

AT

*

HD (Hold Dial Line) ............................................................................ 1-66

AT

*

LA (DTE Circuit 141)........................................................................... 1-68

AT

*

LC (Line Compensation)....................................................................... 1-68

AT

*

LD (DTE Circuit 140)........................................................................... 1-69

AT

*

LE (Dial to Leased Option, Automatic Disconnect) ............................ 1-69

AT

*

LL (Local Analog Loopback Test Busy Out) ....................................... 1-70

AT

*

LN (Link Telephone Numbers) ............................................................. 1-70

AT

*

LS (Low Speed) .................................................................................... 1-71

AT

*

LT (DTE Pin 25) ................................................................................... 1-72

AT

*

MD (PSTN Signaling) .......................................................................... 1-72

AT

*

MF (Modem Flow Control) .................................................................. 1-74

AT

*

MM (Modulation Mode) ...................................................................... 1-74

AT

*

MN (Minimum Rate) ........................................................................... 1-76

AT

*

MR, AT&S (DSR Control) ................................................................... 1-76

AT

*

MS (AT Messages) ............................................................................... 1-76

AT

*

MX (Maximum Rate) ........................................................................... 1-77

AT

*

CN (Enter Telephone Numbers) ............................................... 1-48

*

vi

Contents (continued)

Chapter 1. AT Commands (Continued)

AT

NB (Buffer Option) .............................................................................. 1-77

*

NC (Network Compensation)................................................................ 1-78

AT

*

ND (View Stored Telephone Numbers) ............................................... 1-78

AT

*

OC (External Control) .......................................................................... 1-79

AT

*

OP (External Option Set Select) ........................................................... 1-79

AT

*

OS (Overspeed) .................................................................................... 1-80

AT

*

PE (Enable/Disable Password Protection) ........................................... 1-80

AT

*

PF (Set Protection) ............................................................................... 1-80

AT

*

PN (Unlock Password Protection)......................................................... 1-81

AT

*

PT (Dial Type) ...................................................................................... 1-81

AT

*

PW (Change Password) ........................................................................ 1-82

AT

*

RA (Remote Access) ............................................................................ 1-82

AT

*

RC (Initiate, Terminate, or Abort Remote Configuration Session) ...... 1-83

AT

*

Initiating a Remote Configuration Session with a Dial Modem .............. 1-83

Initiating a Remote Configuration Session with a Leased Line Modem .. 1-85

Terminating a Remote Configuration Session .......................................... 1-86

Aborting a Remote Configuration Session ............................................... 1-86

RE (Initiate/Terminate Restoral) .......................................................... 1-87

AT

*

RP (Parity) ............................................................................................ 1-90

AT

*

RS (RTS Control) ................................................................................. 1-91

AT

*

RT (Auto Retrain) ................................................................................. 1-92

AT

*

SC (Speed Conversion) ........................................................................ 1-93

AT

*

SI (DTE Inactivity) ............................................................................... 1-93

AT

*

SL (Error Correction ID)....................................................................... 1-94

AT

*

SM (Data Transfer Mode) .................................................................... 1-94

AT

*

SR (RTS/DCD Remote Signaling) ....................................................... 1-96

AT

*

ST, AT&V (Modem Status Display) .................................................... 1-97

AT

*

TD (Throughput Delay Minimization) ................................................. 1-97

AT

*

TL (Tone Length) ................................................................................. 1-98

AT

*

TT (Call Timeout)................................................................................. 1-98

AT

*

XC (Error Correction Reliable Messages) ........................................... 1-99

AT

*

ZC (Callback Feature)........................................................................... 1-100

AT

*

ZD (Dial Restricted) ............................................................................. 1-101

AT

*

ZI (Enter Access Security Group Password) ........................................ 1-101

AT

*

ZP (Select Tones with Access Security) ............................................... 1-102

AT

*

ZR (Remote Number Required) ........................................................... 1-102

AT

*

ZS (Simulated Ringback)...................................................................... 1-103

AT

*

ZV (Password Verification) .................................................................. 1-103

AT

*

vii

Contents (continued)

Chapter 2. Front Panel Operation

Introduction .................................................................................................. 2-2

Status/Option Sets/Dialing Menu ................................................................. 2-3

Test Options .................................................................................................. 2-5

Modulation Options ...................................................................................... 2-6

Restoral Options ........................................................................................... 2-8

Restoral Indications .................................................................................. 2-9

Configuring for Dial Restoral ................................................................... 2-10

Interpreting the DTR Option Setting......................................................... 2-13

Error Correction and Data Compression Options ......................................... 2-14

ACU Options ................................................................................................ 2-15

ACU Selection .......................................................................................... 2-16

V.25 bis Data Format ................................................................................ 2-17

NoACU Data Format................................................................................. 2-17

Character Length....................................................................................... 2-18

V.25 bis Character Selection .................................................................... 2-18

Sync Idle ................................................................................................... 2-18

V.25 bis Responses ................................................................................... 2-19

LPDA2 Address ........................................................................................ 2-19

LPDA2 Identification Number.................................................................. 2-20

LPDA2 Determination ............................................................................. 2-20

Terminal Options .......................................................................................... 2-20

Telco Options................................................................................................. 2-23

Dial Line Transmit Level ......................................................................... 2-24

Leased Line Transmit Level ..................................................................... 2-24

Dialing Options ............................................................................................. 2-25

Front Panel Security Options ........................................................................ 2-26

Unlocking the Modem............................................................................... 2-27

Access Security Options................................................................................ 2-28

Group PW Enable/Disable........................................................................ 2-29

If the Answer Modem Is Not Using the Callback Feature........................ 2-30

If the Calling Modem Is Providing the Callback Number ....................... 2-31

Using the Callback Feature with an Originate-Only Modem .................. 2-33

Manual Dialing and Callback DTMF Equivalencies ............................... 2-33

Network Control Options ............................................................................. 2-34

Override Mode ......................................................................................... 2-35

Network Control Address.......................................................................... 2-35

Network Control Port Rate ....................................................................... 2-36

Pass Thru .................................................................................................. 2-36

Remote Configuration Options ..................................................................... 2-37

Setting a Remote Modem's Leased Line Address .................................... 2-40

Searching for a Remote Modem's Leased Line Address .......................... 2-41

Setting or Searching for a Remote Modem's Leased Line Address ......... 2-43

Performing Numeric Entry............................................................................ 2-45

viii

Contents (continued)

Chapter 3. Automatic Calling Interfaces

Introduction .................................................................................................. 3-3

V.25 bis ACU ................................................................................................ 3-3

Call Establishment Methods ..................................................................... 3-6

Modem Configuration .............................................................................. 3-6

Addressed Mode........................................................................................ 3-7

V.25 bis Commands ............................................................................. 3-7

V.25 bis Responses ............................................................................... 3-10

Call Failure Responses ......................................................................... 3-11

Call Progress Responses ...................................................................... 3-12

Result Code Responses......................................................................... 3-12

Reliable Connection Response ............................................................. 3-13

Programming Guide for the V.25 bis Auto-Call Unit (ACU) ................... 3-13

Asynchronous Frame Format ............................................................... 3-14

Synchronous Bit-Oriented Frame Format ............................................ 3-15

Synchronous Character-Oriented Frame Format ................................. 3-16

V.25 bis Control Signaling in Addressed Mode ....................................... 3-17

Idle Condition ...................................................................................... 3-17

Dialog State........................................................................................... 3-18

Connecting State .................................................................................. 3-18

Data State ............................................................................................. 3-19

Disconnecting ...................................................................................... 3-19

Direct Mode............................................................................................... 3-20

Direct Answering ................................................................................. 3-20

Direct Dialing........................................................................................ 3-20

Manual Answering and Dialing................................................................. 3-20

Manual Answering................................................................................ 3-21

Manual Dialing ..................................................................................... 3-21

LPDA2 Command Set................................................................................... 3-22

How to Configure for LPDA2 ACU.......................................................... 3-22

LPDA2 ACU Control Commands ............................................................ 3-22

LPDA2 Message Format........................................................................... 3-23

Information Field Format and Command ................................................. 3-23

Header (H) ........................................................................................... 3-24

Identifier (I)........................................................................................... 3-24

Modem Address (A).............................................................................. 3-24

Command Code (C).............................................................................. 3-24

Data Field (D) ...................................................................................... 3-24

Information Field Format and Response................................................... 3-25

Header (H) Response Field .................................................................. 3-25

Identifier Field (I).................................................................................. 3-25

Modem Address (A) ............................................................................. 3-26

Command Code (C) ............................................................................. 3-26

Sense Byte (SB) ................................................................................... 3-26

Data Field (D) ...................................................................................... 3-26

Framing Rules........................................................................................... 3-27

LPDA2 Dial Command ............................................................................ 3-27

Dial Command Sense Bytes ................................................................. 3-30

Dial Response Data Field ..................................................................... 3-31

ix

Contents (continued)

Chapter 3. Automatic Calling Interfaces (Continued)

LPDA2 Disconnect Command.................................................................. 3-31

Disconnect Command Sense Byte........................................................ 3-31

Disconnect Response Data Field .......................................................... 3-32

Using an External Auto-Call Unit (Bell 801C or Codex 2207)..................... 3-33

To Initiate a Call... ................................................................................ 3-33

To Terminate a Call............................................................................... 3-33

Chapter 4. Testing Your Modem

Introduction .................................................................................................. 4-2

Quick Checks ................................................................................................ 4-2

Automatic Self-Test ...................................................................................... 4-2

Starting the Automatic Self-Test .............................................................. 4-3

Handling Error Messages ......................................................................... 4-3

System T esting............................................................................................... 4-4

326XFAST Synchronous Data Compression Testing .............................. 4-5

Local Analog Loopback Test (AT&T1)..................................................... 4-5

Local Analog Loopback Pattern Test (AT&T8) ....................................... 4-8

Remote Digital Loopback Test (AT&T6) ................................................. 4-10

Remote Digital Loopback Pattern Test (AT&T7) .................................... 4-12

Data Mode Pattern Test ............................................................................ 4-14

Local Digital Loopback (AT&T3) ............................................................ 4-16

Busy Out (ATH1) ..................................................................................... 4-18

Retrain (AT01) .......................................................................................... 4-19

326XFAST DTE Cable Diagnostics ........................................................ 4-20

Chapter 5. Specifications

Introduction .................................................................................................. 5-2

Physical Characteristics ................................................................................ 5-2

Operating Mode Characteristics ................................................................... 5-2

Telephone Line Type ................................................................................ 5-2

FAST Modulation Mode .......................................................................... 5-2

V.32 bis Modulation Mode ....................................................................... 5-2

V.32 Modulation Mode ............................................................................ 5-3

V.22 bis Modulation Mode ....................................................................... 5-3

V.22 Modulation Mode ............................................................................. 5-3

Bell 212 Modulation Mode ...................................................................... 5-3

V.21 Modulation Mode ............................................................................. 5-4

Bell 103 Modulation Mode ...................................................................... 5-4

Environmental Limits ................................................................................... 5-4

Primary Power Requirements ....................................................................... 5-4

Transmitter .................................................................................................... 5-5

Output Level.............................................................................................. 5-5

Transmitter T iming.................................................................................... 5-5

x

Contents (continued)

Appendix A. ASCII/EBCDIC Hexadecimal Equivalents

Appendix B. Options and Displays Worksheet

Index

xi

Chapter 1

AT Commands

Contents

A T, A T& and A T* Command Descriptions ................................................. 1-5

Selecting Options and Settings ................................................................. 1-8

ATD (Dialing an Unstored Telephone Number) ........................................... 1-10

A TDS, AT

ATE (Asynchronous Echo) ........................................................................... 1-11

ATH (Busy Out Test) .................................................................................... 1-11

ATL (Speaker Volume) ................................................................................. 1-11

ATM (Speaker Control)................................................................................. 1-12

ATO1 (Retrain) ............................................................................................. 1-12

ATP, ATT, AT

ATQ (Result Codes) ...................................................................................... 1-13

ATS (S-Register)............................................................................................ 1-14

ATT (Dial Type) ............................................................................................ 1-14

ATV (Result Code Format) ........................................................................... 1-14

ATX (Call Progress) ..................................................................................... 1-15

ATY (Longspace Disconnect) ...................................................................... 1-18

ATZ (Selecting an Option Set) ...................................................................... 1-18

AT& Commands ........................................................................................... 1-19

AT&C (DCD Control) ................................................................................... 1-19

AT&D (DTR Control) .................................................................................. 1-20

AT&F (Reinitialize Memory)........................................................................ 1-22

AT&G (Guard Tone) ..................................................................................... 1-22

AT&I (Display Modem ID) .......................................................................... 1-23

AT&J (Dial Line Jack Types) ........................................................................ 1-24

AT&L (Line Type) ........................................................................................ 1-25

AT&M (AT Data Format) ............................................................................. 1-26

AT&P (Pulse Cycle) ...................................................................................... 1-27

A T&R, AT
A T&S, AT

AT&T (Test) .................................................................................................. 1-30

AT&T4, AT&T5 (Accept RDL) .................................................................... 1-31

DS (Dialing a Stored Telephone Number) ............................... 1-10

*

PT (Dial Type) ..................................................................... 1-13

*

CT (CTS Control) .................................................................... 1-28

*

MR (DSR Control) ................................................................... 1-29

*

AT Commands 1-1

Contents (continued)

A T&V, AT*ST (Modem Status Display)...................................................... 1-31

Operating Status Messages ....................................................................... 1-32

DTE Rate/Status Summary ...................................................................... 1-34

Error-Correction and Data-Compression Status........................................ 1-35

Transmit and Receive Throughput and Link Utilization Status Display .. 1-36

EIA/TIA 232-D (CCITT V.24) Signal Status ............................................... 1-37

Status Summary Line ............................................................................... 1-38

Display Modem ID ................................................................................... 1-41

CQMS Parameter Status ........................................................................... 1-41

AT&W (Save Changes: Creating New Option Sets)..................................... 1-45

AT&X (Clock) .............................................................................................. 1-47

AT&Y (Power Up in Option Set) ................................................................. 1-47

A T&Z, AT

Commands ........................................................................................... 1-49

AT

*

AA (Answer) ........................................................................................ 1-49

AT

*

AP (Adaptive Rate) .............................................................................. 1-50

AT

*

AS (Answer in Restoral) ...................................................................... 1-51

AT

*

AY (Auto Type) .................................................................................... 1-52

AT

*

BD (Blind Dial) .................................................................................... 1-52

AT

*

BK (Break Handling) ........................................................................... 1-53

AT

*

CA (Answer/Originate Mode)............................................................... 1-53

AT

*

CD (DCD Loss Disconnect).................................................................. 1-54

AT

*

CM (Connect Message)......................................................................... 1-54

AT

*

CN, AT&Z (Entering Telephone Numbers) ......................................... 1-54

AT

*

CT , AT&R (C, TS) ................................................................................ 1-54

AT

*

DA (Default Dialing) ............................................................................ 1-55

AT

*

DB (Buffer Delay) ................................................................................ 1-56

AT

*

DC (Data Compression) ....................................................................... 1-57

AT

*

DD (Dial Wait) ..................................................................................... 1-57

AT

*

DE (DTE Rate)...................................................................................... 1-58

AT

*

DF (Data Format) ................................................................................. 1-59

AT

*

DI (Leased to Dial Option) ................................................................... 1-59

AT

*

CN (Enter Telephone Numbers) ............................................... 1-48

*

1-2 AT Commands

Contents (continued)

AT*DL (RTS/CTS Delay) ........................................................................... 1-60

DP (Pause Delay) ................................................................................. 1-60

AT

*

DR (Auto Redial) ................................................................................. 1-61

AT

*

DS, ATDS (Dial a Stored Telephone Number) ..................................... 1-61

AT

*

DT (DTR Delay) .................................................................................. 1-61

AT

*

EC (Error Correction) ........................................................................... 1-62

AT

*

FC (Fast Call)........................................................................................ 1-63

AT

*

FL (Flow Control) ................................................................................ 1-64

AT

*

HD (Hold Dial Line) ............................................................................ 1-66

AT

*

LA (DTE Circuit 141)........................................................................... 1-68

AT

*

LC (Line Compensation)....................................................................... 1-68

AT

*

LD (DTE Circuit 140)........................................................................... 1-69

AT

*

LE (Dial to Leased Option, Automatic Disconnect) ............................ 1-69

AT

*

LL (Local Analog Loopback Test Busy Out) ....................................... 1-70

AT

*

LN (Link Telephone Numbers) ............................................................. 1-70

AT

*

LS (Low Speed) .................................................................................... 1-71

AT

*

LT (DTE Pin 25) ................................................................................... 1-72

AT

*

MD (PSTN Signaling) .......................................................................... 1-72

AT

*

MF (Modem Flow Control) .................................................................. 1-74

AT

*

MM (Modulation Mode) ...................................................................... 1-74

AT

*

MN (Minimum Rate) ........................................................................... 1-76

AT

*

MR, AT&S (DSR Control) ................................................................... 1-76

AT

*

MS (AT Messages) ............................................................................... 1-76

AT

*

MX (Maximum Rate) ........................................................................... 1-77

AT

*

NB (Buffer Option) .............................................................................. 1-77

AT

*

NC (Network Compensation)................................................................ 1-78

AT

*

ND (View Stored Telephone Numbers) ............................................... 1-78

AT

*

OC (External Control) .......................................................................... 1-79

AT

*

OP (External Option Set Select) ........................................................... 1-79

AT

*

OS (Overspeed) .................................................................................... 1-80

AT

*

PE (Enable/Disable Password Protection) ........................................... 1-80

AT

*

PF (Set Protection) ............................................................................... 1-80

AT

*

AT Commands 1-3

Contents (continued)

AT*PN (Unlock Password Protection)......................................................... 1-81

PT (Dial Type) ...................................................................................... 1-81

AT

*

PW (Change Password) ........................................................................ 1-82

AT

*

RA (Remote Access) ............................................................................ 1-82

AT

*

RC (Initiate, Terminate, or Abort Remote Configuration Session) ...... 1-83

AT

*

Initiating a Remote Configuration Session with a Dial Modem .............. 1-83

Initiating a Remote Configuration Session with a Leased Line Modem .. 1-85

Terminating a Remote Configuration Session .......................................... 1-86

Aborting a Remote Configuration Session ............................................... 1-86

RE (Initiate/Terminate Restoral) .......................................................... 1-87

AT

*

RP (Parity) ............................................................................................ 1-90

AT

*

RS (RTS Control) ................................................................................. 1-91

AT

*

RT (Auto Retrain) ................................................................................. 1-92

AT

*

SC (Speed Conversion) ........................................................................ 1-93

AT

*

SI (DTE Inactivity) ............................................................................... 1-93

AT

*

SL (Error Correction ID)....................................................................... 1-94

AT

*

SM (Data Transfer Mode) .................................................................... 1-94

AT

*

SR (RTS/DCD Remote Signaling) ....................................................... 1-96

AT

*

ST, AT&V (Modem Status Display) .................................................... 1-97

AT

*

TD (Throughput Delay Minimization) ................................................. 1-97

AT

*

TL (Tone Length) ................................................................................. 1-98

AT

*

TT (Call Timeout)................................................................................. 1-98

AT

*

XC (Error Correction Reliable Messages) ........................................... 1-99

AT

*

ZC (Callback Feature)........................................................................... 1-100

AT

*

ZD (Dial Restricted) ............................................................................. 1-101

AT

*

ZI (Enter Access Security Group Password) ........................................ 1-101

AT

*

ZP (Select Tones with Access Security) ............................................... 1-102

AT

*

ZR (Remote Number Required) ........................................................... 1-102

AT

*

ZS (Simulated Ringback)...................................................................... 1-103

AT

*

ZV (Password Verification) .................................................................. 1-103

AT

*

1-4 AT Commands

AT, AT& and AT* Command Descriptions

This chapter provides an alphabetic list of the AT commands that you can execute
from the control terminal and the modem front panel.

AT commands and options are described in the following sequence:

• A pull-out main menu figure (Figure 1-1) illustrating all AT, AT& and AT
command settings, front panel options, and option settings

• A front panel option figure in the left margin describing how to select a
command on the modem front panel

• Industry-standard AT and AT& commands that begin with AT

• Motorola-enhanced AT commands, which begin with AT

• A list of the menu's front panel options, if any, that have AT-equivalent control
terminal commands

NOTES:

1) For descriptions of front panel options and option settings that do not have A T
command equivalents, see Chapter 2, Front Panel Operation. Chapter 2 is
organized to follow the structure of the front panel menu tree; the main menu
is divided into submenu sections, describing the appropriate options and
settings. For a list of AT commands that do not have front panel equivalents,
see “Non-Configuration AT Commands” in Chapter 5, Using the AT
Automatic Calling Interface, of the 326X Series Modem User’s Guide.

2) Throughout this guide, all references to the 326X Series Modem apply to the
326X V.32 bis, 326XFAST, and 326XFAST-SDC Modems, unless specifically
stated otherwise.

*

*

AT Commands 1-5

Figure 1-1. 326X Series Main Menu

1-6 AT Commands

AT Commands 1-7

Selecting Options and Settings

The figure in the left margin that precedes each AT command illustrates the main­menu option, the right-arrow ( ) button indicating that you must press the across
key until the described option appears, and the resulting submenu option. For
example, the first AT command in the following list is ATD, Dialing an Unstored
Telephone Number. In the figure accompanying this entry, you see:

• The main-menu option to access: Data 9600 T/D?

• The front panel control key to press to display the submenu

• The ATD Command prompt: Enter Then Dial

Each front panel option has a default setting. Some front panel defaults are
determined by the assigned factory-preset option sets. These preset defaults are
exclusive to the particular option set. The other f actory options are not e xclusive to a
particular option set and they always have the same default setting, regardless of
which factory-preset option set you are using.

For options that belong to option sets, a number or the word “all” in parentheses
appears underneath the selection. A number tells you which option set(s) the setting
is a default for. If the word “all” appears under a setting, it means that the setting is
the default setting for all four option sets.

As an example, the option setting portion of the DTR Control (AT&D) option
appears as follows:

Option Setting

High
(1, 4L)
Escape
Discon
(4D)
Reset
Tail

1

(2)

108.1

1

(3)

108.2
(2, 3)

1

Default for the 326XFAST-SDC Modem

1-8 AT Commands

The defaults for the DTR Control option for the 326X V.32 bis and 326XFAST
modem are:

• High for Option sets 1 and 4 (the “L” next to the 4 indicates that High is the
default for Option Set 4 for leased line modems (models 3261, 3263, 3266,

3268)

• Discon for Option set 4 (the “D” next to the 4 indicates that Discon is the
default for Option set 4 for dial modems (models 3260, 3262, 3265, 3267)

• 108.2 for Option sets 2 and 3

The defaults for the DTR Control option for the 326XFAST-SDC modem are:

• High for Option sets 1 and 4 (the “L” next to the 4 indicates that High is the
default for Option Set 4 for leased line modems (models 3261, 3263, 3266,

3268)

• Tail for Option set 2

• 108.1 for Option set 3

In this example, since High is the default for Option sets 1 and 4L for all products
(326X V.32 bis, 326XFAST, and 326XFAST-SDC), no product-specific distinction is
made. Where one setting (for example, 108.1) is the default for Option set 3 in the
326XFAST-SDC product, a footnote indicates the difference.

Unless specified by a “D” or an “L, ” def aults apply to all models. For options that do
not belong to option sets, the default setting is designated by the word “default” in
parentheses underneath the setting.

The following sections describe industry-standard AT commands that begin with AT.
NOTES:

1) The conventions described for identifying front panel option settings and
defaults apply to the 326X V.32 bis, 326XFAST, and 326XFAST-SDC
Modems. Option settings that vary are clearly marked indicating to which
product the default setting applies.

2) Throughout this chapter, AT commands are listed in table format. In the
“AT Command Setting” column, the AT reference has been omitted; however,
be sure to enter the entire AT command. For example:

AT*ZCO

AT Commands 1-9

D, DS, *DS

ATD (Dialing an Unstored Telephone Number)

DATA 9600 T/D?

•••

Enter Then Dial

The ATD (Enter Then Dial) command allows you to dial a telephone number (up to
50 characters) without storing it in your modem's telephone book.

The ATD Command

You can dial a telephone number directly from your keyboard. To do this, enter the
ATD command followed by the telephone number and a carriage return.
For example:

ATD5551234<CR>

The Front Panel
See the "Performing Numeric Entry" section in Chapter 2 of this guide for details on

how to use numeric entry.

ATDS, AT*DS (Dialing a Stored Telephone Number)

DATA 9600 T/D?

• • •

Dial From #

The A TDS and A T*DS (Dial From #) commands dial a number stored in one of the
modem's nine “telephone book” addresses. NOTE: Enter a telephone number into
your modem's telephone book before attempting to use this option. See “AT&Z,

CN (Enter Phone Numbers)” for information on entering phone numbers.

AT

*

Option Setting AT Command Setting

1 – 9 1 – 9
Option Setting AT Command Setting

The ATDS or A T

To dial a stored telephone number using AT commands, enter:

ATDS

or

AT*DS

followed by the telephone book address number and a carriage return <CR>. If you
enter the ATDS or AT
dials the number stored in address 1. NOTE: The A TDS and A T
also be entered in the format ATDS=n or AT

The Front Panel

To use the front panel to dial a telephone number stored in the modem's telephone
book:

1) Step across the Status/Option Sets/Dialing menu by pressing until you see:

Dial from #=n

2) Press the to select the telephone book address for the number you want to
dial and press . The modem dials the telephone number stored in the
designated telephone book address.

DS Command

*

DS command without a number following it, the modem

*

DS=n.

*

DS commands can

*

1-10 AT Commands

ATE (Asynchronous Echo)

The ATE (Async Echo) command enables the modem to echo all commands recei ved

ACU OPT’S

Async Echo

• • •

from an asynchronous DTE.

Option Setting

Off 0 The modem does not echo asynchronous

On
(all)

ATH (Busy Out Test)

The ATH command enables you to initiate a Busy Out test.

TEST OPT’S

Test

• • •

Option Setting

Busy Out 1 Makes the modem appear busy to incoming calls.

End Test 0 If Busy Out is enabled, ATH0 will disconnect the

E, H, L

AT Command
Setting Description

commands to the DTE.

1 The modem echoes asynchronous commands to

the DTE.

AT Command
Setting Description

To configure the modem to use the Busy Out
feature, refer to the AT*LT (DTE Pin 25) option
description in this chapter

busy out condition. Also, if the modem is in
“escape mode” (the modem has transitioned to
command state from the data state—online or
test), the ATH0 command disconnects the
modem.

Refer to Chapter 4, of this guide or the AT&T option description within this chapter,
for a detailed description of how to initiate and terminate the Busy Out test.

ATL (Speaker Volume)

The ATL (Volume) option sets the speaker volume in the modem.

TELCO OPT’S

Volume

• • •

Option Setting

Medium
(all)

Loud 3 Loud
Soft 0,1 Soft

AT Command
Setting Description

2 Medium

AT Commands 1-11

M, O1

ATM (Speaker Control)

The ATM (Speaker) option controls the operation of the modem's speaker.

TELCO OPT’S

ATO1 (Retrain)

TEST OPT’S

Speaker

Test

• • •

• • •

Option Setting

Dialing
(all)

On 2 The speaker is always on.
Security 3 The speaker goes on when dialing is completed

Off 0 The speaker is always off.

ATO1 allows you to return to data mode and initiate a retrain with the remote
modem. Refer to Chapter 4, Testing Your Modem, or the AT&T option description
within this chapter for a description of how to initiate a retrain.

Option Setting

Retrain 1 Allows you to initiate a retrain with the remote

AT Command
Setting Description

1 The speaker comes on while dialing and training

but stays off when the modem enters data mode.

and goes off when the modem enters data mode.

AT Command
Setting Description

0 Return to data mode.

modem.

1-12 AT Commands

ATP, ATT, AT*PT (Dial Type)

P, T, *PT, Q

DIALING OPT’S

Dial

• • •

The A TP, ATT and A T*PT (Dial) commands determine how the modem dials
telephone numbers: in tone, pulse, or auto tone/pulse. The modem refers to this
option setting if it does not encounter any T or P modifiers in the telephone number.

AT Command

Option Setting

Tone ATT

Pulse ATP

Auto AT*PT2 The auto-call unit attempts to tone dial when

Setting Description

The modem uses tone (DTMF) dialing unless

AT*PT0

PT1

AT

*

otherwise specified by the T or P dial modifiers
in a telephone number.

The modem uses pulse dialing unless otherwise
specified by the T or P dial modifiers in a
telephone number.

initiating a call. If tone dialing is not possible,
pulse dialing is used.

For this feature to work correctly, the first
character in a dial string must be a digit, and not
a dial modifier. A T or P in the dial string
overrides this setting for that dial string.

NOTE: Do not use the Auto setting if you are in
a PBX environment. If a dial tone is detected
after the first digit, the phone number will be
redialed as a pulse which may not be
recognizable by the PBX.

ATQ (Result Codes)

ACU OPT’S

• • •

Rslt Code

The ATQ (Rslt Code) command selects whether result codes (including Call
Progress messages) are displayed.

Option Setting

Enable
(all)

Disable 1 Result codes are not displayed at the DTE.
Orig 2 Result codes are output to the DTE only when

AT Command
Setting Description

0 Result codes are displayed at the DTE.

operating as an originate modem.

AT Commands 1-13

S, T , V

ATS (S-Register)

Data 9600 T/D?

• • •

S-Reg xxx=nnn

The ATS (S-Reg xxx) command allows you to view and set the various S-Registers
that are supported by the 326X Series Modems. S-Registers contain values that
determine and reflect how the modem operates and executes commands. You can
view and change S-Register v alues via the AT commands described in this section or
through the front panel option. If an invalid S-Register is entered, the modem
responds with an OK, but no action occurs.

See the "Performing Numeric Entry" section in Chapter 2 for details on how to use
numeric entry to enter the appropriate S-Register. For a full description of
S-Registers, see the “S-Registers” section in Chapter 5 of the 326X Series Modem
User’s Guide.

ATT (Dial Type)

See the ATP command description described earlier.

ATV (Result Code Format)

The ATV (RsltForm) command selects the format of result codes that are sent to your

ACU OPT’S

RsltForm

• • •

DTE.

Option Setting

Numeric 0 Result codes are sent to your DTE as numbers

Verbose
(all)

AT Command
Setting Description

(short form).

1 Result codes are sent to your DTE as full words

(long form). Refer to Appendix A of the 326X
Series Modem User’s Guide for a summary of
result codes.

1-14 AT Commands

ATX (Call Progress)

The ATX (Call Progress) command determines whether the modem waits for call

ACU OPT’S

Call Progress

• • •

progress signals or blind dials when establishing calls.

Option Setting

0 0 The modem uses only NO CARRIER and

1 1 The modem uses only NO CARRIER, CONNECT ,

2 2 The modem waits for dial tone and uses only NO

3 3 The modem detects busy signal and uses only NO

4 4 The modem waits for dial tone and detects busy

X

AT Command
Setting Description

CONNECT result codes.

and CONNECT <Rate> result codes.

CARRIER, CONNECT, CONNECT <Rate> and
NO DIALTONE result codes.

CARRIER, CONNECT, CONNECT <Rate>, and
BUSY result codes.

signal. Only NO CARRIER, CONNECT,
CONNECT <Rate>, BUSY, and NO DIAL TONE
result codes are used.

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

The following section discusses how each ATX (Call Progress) command setting
works.

ATX0 or 1 (Call Progress=0 and 1)

The modem goes off-hook, waits for the amount of time specified by the Blind Dial
option, and blind dials whether or not dial tone is present. After processing all of the
characters in the dial string, including dial modifiers, the modem looks for data
carrier for the amount of time specified by the AT
If the modem does not detect data carrier before the time specified by the AT
(Call Timeout) command expires, it hangs up and displays:

NO CARRIER

If the modem does detect data carrier, it displays either:

CONNECT

(for setting 0) or a speed-specific connect message (for setting 1). If your modem is
using error correction and the AT
command, the modem also displays the suffix:

RELIABLE

or

XC1 or AT*XC2 (Rel Msg=Short or Long)

*

TT (Call Timeout) command.

*

*

TT

RELIABLE EC=(xxx) DC=(yyy)

AT Commands 1-15

X

ATX2 (Call Progress=2)

The modem goes off-hook and looks for dial tone. If it detects dial tone, the modem
dials. If the modem does not detect dial tone, it hangs up and displays:

NO DIALTONE

After processing all of the characters in the dial string, including dial modifiers, the
modem looks for data carrier for the amount of time specified by the AT
Timeout) command. If data carrier is not detected before the time specified by the
Call Timeout option expires, the modem hangs up and displays:

NO CARRIER

If data carrier is detected, the modem displays a speed-specific connect message.
If the modem is configured for error correction, and AT
(Rel Msg=Short or Long)) is selected, the modem also displays the suffix:

RELIABLE

or

RELIABLE EC=(xxx) DC=(yyy)

ATX3 (Call Progress=3)

The modem goes off-hook, waits for the amount of time specified by the AT
(Blind Dial) command, and then blind dials. After processing all of the characters in
the dial string, including dial modifiers, the modem starts the AT
command timer and looks for a busy signal, ringback, and data carrier. If a busy
signal is detected before the time specified by the AT
expires, the modem hangs up and displays:

XC1 or AT*XC2

*

TT (Call Timeout)

*

TT (Call Timeout) command

*

TT (Call

*

*

BD

BUSY

The length of time between finishing dialing and displaying the BUSY message is
the amount of time the modem takes to detect the busy signal. If data carrier is not
detected before the time specified by the AT
the modem hangs up and displays:

NO CARRIER

The length of time between finishing dialing and displaying the NO CARRIER
message is the amount of time specified by the AT
If data carrier is detected, the modem displays a speed-specific connect message.
If error correction is enabled and AT
commands are selected, the modem also displays the suffix:

RELIABLE

or

RELIABLE EC=(xxx) DC=(yyy)

XC1 or AT*XC2 (Rel Msg=Short or Long)

*

TT (Call Timeout) command expires,

*

TT (Call Timeout) command.

*

1-16 AT Commands

X

ATX4 (Call Progress=4)

The modem goes off-hook and looks for dial tone. If a dial tone is detected, the
modem dials. If not, the modem hangs up and displays:

NO DIALTONE

After processing all of the characters in the dial string, including dial modifiers, the
modem looks for a busy signal, ringback, and data carrier. If the modem detects a
busy signal before the time specified by the AT
expires, the modem hangs up and displays:

BUSY

The length of time between finishing dialing and displaying the BUSY message is
the amount of time it takes the modem to detect the busy signal. If the modem does
not detect data carrier before the time specified by the AT
command expires, the modem hangs up and displays:

NO CARRIER

The length of time between finishing dialing and displaying the NO CARRIER
message is the amount of time it takes the modem to detect ringback, plus the
amount of time specified by the AT
detected, the modem displays a speed-specific connect message. If the modem is
configured for error correction and AT
the modem displays the suffix:

TT (Call Timeout) command. If data carrier is

*

XC1 or AT*XC2 (Rel Msg=Short or Long),

*

TT (Call Timeout) command

*

TT (Call Timeout)

*

or

RELIABLE

RELIABLE EC=(xxx) DC=(yyy)

AT Commands 1-17

Y, Z

ATY (Longspace Disconnect)

MODULATION OPT’S

Longspace

• • •

to the AT

Option
Setting

Off
(all)

On 1 The modem disconnects when it receives space

MD command.

*

AT Command
Setting Description

0 The modem does not disconnect when it receives

ATZ (Selecting an Option Set)

The ATY (Longspace) command enables the long-space disconnect function. Refer

DATA 9600 T/D?

• • •

Select Options

The ATZ (Select Options) command chooses which of the four option sets, stored in
nonvolatile memory, is used by the modem. When you use Select Options or the ATZ
command, the new option set takes effect immediately. For a description of each
action set, see Chapter 4, Configuring Your Modem, in the 326X Series Modem
User’s Guide.

Option
Setting

1 0, 1 Option Set 1
2 2 Option Set 2
3 3 Option Set 3
4 4 Option Set 4

AT Command
Setting Modem Uses

space that exceeds 1.6 seconds in duration. When
terminating a call, the modem does not send
continuous space for 4 seconds.

that exceeds 1.6 seconds in duration. When
terminating a call, the modem sends continuous
space for 4 seconds.

1-18 AT Commands

NOTE: The modem disconnects from the line when the ATZ command is entered.
Also, any test in progress is immediately terminated. Since any AT command that
follows the ATZ command is ignored by the modem, make sure that the ATZ
command is the last one entered in an AT command string. Use the A T&Y command
to select with which option set the modem powers up.

AT& Commands

The following sections describe industry-standard AT commands that begin with
AT&.

AT&C (DCD Control)

&C

TERMINAL OPT’S

DCD

• • •

The AT&C (DCD) command determines how the modem sets the DCD signal. The
modem signals the DTE with DCD on EIA/TIA 232-D Pin 8 (V.24 Circuit 109).

Option
Setting

High
(1)

Normal
(2, 3, 4)

ACU On 2 DCD is on when the modem is disconnected so that

Remote 3 This setting applies to simulated half-duplex

Wink 4 DCD is always on; however, it will drop after

AT Command
Setting Description

0 DCD is always on.

1 DCD is off during dialing and also while the modem is

training with the remote modem. DCD is on in data
mode. When the modem is disconnected from the
telephone line, DCD is off.

terminals requiring this signal can use the ACU. During
dialing, DCD goes off until both local and remote
modems train and are ready to pass data. DCD is on in
data mode. DCD drops on a disconnect momentarily.

applications and works only if the remote modem also
supports RTS/DCD signaling. When the remote DTE
turns RTS on, DCD is forced on at the local modem. The
local modem can receive data only during this period.
Once the remote DTE drops RTS, DCD at the local
modem follows. The Rem RTS/DCD option allows you
to choose the type of RTS/DCD signaling.

For the Remote setting to work properly, set the remote
modem's A T*RS (RTS) command to AT*RS2
(Remote). Also, make certain that the Direct data
transfer mode is in use, and that neither the V.21 nor the
Bell 103 modulation mode is in use. If the direct data
transfer mode is not in use, or the V.21 or Bell 103
modulation mode is in use, DCD behaves as if
DCD=Normal.

disconnect and remain low momentarily.

AT Commands 1-19

&D

AT&D (DTR Control)

TERMINAL OPT’S

326X V .32
bis Modem

High (1, 4L) High (1, 4L) High (1, 4L) 0 The modem ignores DTR from the DTE. The

Escape Escape Escape 1 When ACU Select=AT and AT Fortbm=Async

Discon (4D) Discon (4D) Discon 2 The modem hangs up and enters command mode

Reset Reset Reset 3 This setting is similar to Discon except that an

• • •

DTR

Option Setting

326XFAST
Modem

The local DTE uses DTR (Pin 20) to signal the modem.

326XFAST­SDC Modem

AT Command
Setting Description

modem reads DTR as always high. Use this setting
if the DTE does not provide DTR, or if you plan to
use DTR/CTS flow control with the error­correction feature.

(AT&M), the modem enters the AT escape mode
when an on-to-off DTR transition is detected while
modem is in data or test mode.

when an on-to-off DTR transition is detected, while
the modem is in data, test, or escape mode. If DTR
is low, the modem does not auto-answer.

on-to-off DTR transition also causes the modem to
reinitialize its memory (the equivalent of executing
the ATZ command). If DTR is low, the modem
auto-answers.

The option set to which the modem resets is
determined by AT&Y (Power Up In option). If the
AT&Y (Power Up In) command is set for 1, 2, 3, or
4, the designated option set is loaded. If Old is
selected, the currently selected option set is
reloaded.

If DTR is dropped during a test (such as RDL,
LAL, LDL, RDL Pattern, etc.), the modem
disconnects from the line and resets memory to the
selected option set.

NOTE: A reset can change the value of the AT&D
(DTR) command setting from Reset to another
setting.

The AT&D (DTR) command determines how the modem interprets the DTR signal.

1-20 AT Commands

Option Setting

326X V .32
bis Modem

Tail Tail Tail

108.1 108.1 108.1

108.2
(2, 3)

326XFAST
Modem

108.2
(2, 3)

326XFAST­SDC Modem

1

(2)

(3)

108.2 6 When the modem is disconnected from the

&D

AT Command
Setting Description

4 This setting is similar to 108.1 except that the

modem auto-answers an incoming call even if DTR
is off. Use the Tail option if you plan to use the
modem in a tail circuit to a high-speed leased line
modem or to other devices using DTR and DSR.
When DTR transitions from off to on, the modem
connects to the telephone line and dials if the
Default Dial option is enabled. Use the Tail option
if you have an intelligent terminal which must dial
out and answer calls without continually
monitoring for a ringing signal.

5 The DTR signal emulates the function of the Talk/

Data ( at the Home position) key on the modem
front panel. An off-to-on DTR transition instructs
the modem to connect to the telephone line. If the
modem detects an incoming call, the call is
connected. If the modem does not detect an
incoming call and you have enabled the AT
(Default Dial) command, the modem dials the
number specified. If the AT*DA (Default Dial)
command is disabled, the modem refers to the
AT*MM (Modulation Mode option in the
MODULATION OPT'S menu.) If set to answer, the
modem goes off-hook and sends an answer-back
tone. An on-to-off DTR transition disconnects the
modem from the telephone line. If DTR is low, the
modem does not
auto-answer.

telephone line and the DTE turns DTR on, the
modem responds to all V.25 bis and all AT
commands. When the DTE turns DTR off, the
modem does not respond to dialing and answering
AT commands, but responds to all other AT
commands. Also with DTR of f, the modem ignores
all V.25 bis commands. The DTR signal must
remain on throughout the course of a connection.
An on-to-off DTR transition disconnects the
modem from the telephone line. If DTR is low, the
modem does not auto-answer.

*

DA

AT Commands 1-21

&F, &G

AT&F (Reinitialize Memory)

DATA 9600 T/D?

Reinit Memory?

• • •

The AT&F (Reinit Memory?) command is used to reset your modem to the factory­default option settings. The four factory default option sets are restored, and all
stored telephone numbers are deleted.

The AT&F Command

Enter:

A T&F<CR>

The modem front panel displays:

326x Initial

and the terminal displays:

OK

The factory-programmed option sets are now in place.

The Front Panel

When you press the modem first asks you:

Reinit All Mem?

Be sure you want to reinitialize the modem's memory before you press again.
The modem displays:

326x Initial

indicating that the original factory-programmed option sets are now in place.

AT&G (Guard Tone)

MODULATION OPT’S

Guard T one

The AT&G (Guard Tone) command determines what type of guard tone the modem

• • •

uses in V.22 bis operation. The proper guard tone (AT&G) option setting is required
by your PTT. Leave this option set to Off unless your PTT requires the use of guard
tone.

Option Setting

Off 0 The modem does not use a guard tone.
550 1 The modem uses a guard tone of 550 Hz.
1800 2 The modem uses a guard tone of 1800 Hz.

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

1-22 AT Commands

AT&I (Display Modem ID)

&I

DATA 9600 T/D?

DTE 19.2 RELIABL

• • •

The AT&I (Display Modem ID) command allows you to view on your control
terminal screen non-action information that identifies your modem. This information
is referred to as the short form status snapshot display.

The following command option list describes short form modem identification
information.

AT Command Setting Description

0 Software part number
1 Factory product code
2 Country code
3 Product code
4 Network control address (optional)
5 Serial number

The Front Panel

You can also view modem status snapshot by using the front panel. Press until
DTE 19.2 RELIABL appears, and press until Display Modem Id appears.

AT Commands 1-23

&J

AT&J (Dial Line Jack Types)

The AT&J (Telco) command allows you to make the correct registered jack selection

TELCO OPT’S

• • •

Telco

that is compatible with your equipment. The Federal Communications Commission
(FCC) is a telecommunications and standards organization that specifies a series of
registered jacks for use with a dial line network (sometimes referred to as PSTN).
These jacks are designated as RJxxx-type jacks, where RJ means Registered Jack
and xxx specifies the series of the jack.

For example, RJ11 indicates that the jack is a registered jack from series 11.
Sometimes the jack designation is followed by a letter (RJ11C) that indicates the
jack housing style. Jacks specified under FCC Part 68 fit into one of the following
categories: Permissive (voice) or Programmable (data).

AT Command

Option Setting

RJ11C 0 This 6-pin modular jack type is the most

RJ45S 2 This 8-pin modular jack type is the most

RJ16CS 3 This 6-pin modular jack type is a special

RJ4MB 4 This 8-pin modular programmable data mode

Setting Description

common permissive data mode (voice) jack
arrangement found in the home or office and
operates on a single-line bridged tip-and-ring
voice or low-speed data application service.

common programmable data mode (data) jack
arrangement and permits the use of an exclusion­key telephone. This jack also operates on a
single-line bridged tip-and-ring voice or low­speed data application service.

permissive data mode jack arrangement that
allows use of an exclusion-key telephone.

jack arrangement supports Make Busy operation.
Using this jack type, you can make the modem
appear to be off-hook to the central telephone
office.

1-24 AT Commands

NOTE: These settings are country-specific.Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT&L (Line Type)

The AT&L (Line) command sets the type of telephone line used by the modem. If

MODULATION OPT’S

Line

• • •

you change this option while the modem has a dial-line connection, the change does
not take effect until you disconnect the line. When the modem is configured for any
one of the AT
originating modem disconnects from the dial line and returns to the leased line
unless the Auto Redial or Link Phone # options are enabled.

RE option settings except 108.ACU or 116.ACU, if a call fails, the

*

&L

Option
Setting

Dial
(1, 2, 3, 4D)

2W Lease
(4L)

4W Lease 2 The modem communicates over a 4-wire leased line.

AT Command
Setting Description

0 The modem communicates over dial lines in dial

applications only.

1 The modem communicates over a 2-wire leased line.

The A CUs (AT and V.25 bis) are not functional when
the modem is connected to a leased line.

The A CUs (AT and V.25 bis) are not functional when
the modem is connected to a leased line.

AT Commands 1-25

&M

AT&M (AT Data Format)

ACU OPT’S

AT Form

• • •

The AT&M (AT Form) command determines the format of data when the ACU
Select option is set to AT.

NOTE: To enable 326XFAST-SDC (if not using one of the predefined option sets),
once you have selected the AT ACU, make sure you select one of the synchronous
data formats (Sync Data, DTR Dial, or Man Dial) described below

. Also make sure

you select one of the reliable data transfer modes (Reliable, Auto Reliable, or Speed
Auto Reliable) using the Mode (AT

Option
Setting

Async
(all)

Sync Data 1 This setting is intended for terminals capable of

DTR Dial 2 When an off-to-on DTR transition is detected, the

Man Dial 3 DTR signals toggle between talk and data modes. With

AT Command
Setting Description

0 The modem is compatible with asynchronous DTEs and

SM) option.

*

uses the AT command set and auto-call functions.

communicating either synchronously or asynchronously
over the same serial port. When disconnected from the
dial line, communication between the modem and DTE is
asynchronous. The AT command set and auto-call
functions are used to establish calls. Once in data mode,
the modem exchanges data synchronously with the
remote modem. An on-to-off DTR transition causes the
modem to disconnect from the dial line. This option is
designed for use with the AT*DT (DTR Delay option in
the TERMINAL OPT'S menu) command. The AT*DT
command controls the length of time that your modem
holds DTR high (the amount of time you have to switch
from an asynchronous to a synchronous terminal). If
DTR transitions from on to off while you are switching to
a synchronous terminal, your modem disconnects from
the dial line.

modem automatically dials the number stored in the
memory location designated by the Default Dial option
setting. Once connected, the modems transmit data
synchronously. If DTR transitions from on to off, the
modem hangs up and returns to the asynchronous
command mode. If DTR is low, the modem does not
auto-answer.

DTR off, numbers can be dialed from a telephone. Once
an answer tone is heard, the telephone is hung up, and
DTR is raised; the modems connect and send data
synchronously. If DTR is dropped, the modems
disconnect.

1-26 AT Commands

AT&P (Pulse Cycle)

The AT&P (Pulse Cycle) command determines the “make” percentage of the dialing

DIALING OPT’S

Pulse Cycle

pulse make/break ratio.

• • •

Option
Setting

40% 0 The make/break ratio is 40:60.
33% 1 The make/break ratio is 33.5:66.5.
38% 2 The make/break ratio is 38.5:61.5.

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

&P

AT Command
Setting Description

AT Commands 1-27

&R, *CT

AT&R, AT*CT (CTS Control)

The A T&R and A T*CT (CTS) commands determine how the modem sets the CTS

TERMINAL OPT’S

CTS

• • •

signal. The modem signals the DTE with the CTS on EIA/TIA 232-D Pin 5
(V.24 Circuit 106). The CTS signal discussed below is the state of the CTS signal
after the setting of the modem's RTS option has been followed. In order for CTS to
follow the RTS signal from the DTE, set the RTS option to Normal.

Option
Setting

High AT*CT0

Normal
(2, 3, 4)

ACU On AT*CT2 CTS is on in ACU mode, goes off during training/

AsynSync
(1)

RTS A T*CT4 CTS follows RTS. Use this selection if your application

AT Command
Setting Description

CTS remains on at all times. Use this setting if you plan

AT&R1
AT*CT1 The modem controls CTS as required in normal

AT*CT3
AT&R0

to use RTS/CTS or DTR/CTS flow control.

handshaking. For V.25 bis ACU operation, CTS follows
DTR in command state; CTS is off during training/
retraining and follows RTS in data mode. For AT ACU
operation, CTS follows RTS in command state; CTS is
off in training/retraining and follows RTS in data mode.
If an ACU is not selected, CTS is low.

retraining, and follows RTS in data mode.
CTS is on in asynchronous mode.

CTS is off in synchronous, ACU mode. If the data
transfer mode is synchronous, CTS is off during training/
retraining and follows RTS in data mode. When CTS
follows RTS in data mode, the setting of the RTS/CTS
Delay option applies (if Mode=Direct).

requires CTS to immediately follow RTS.
When CTS=RTS, the RTS/CTS Delay (AT*DL) option
is not available. If one of these flow control methods is
used: Flow=RTS/CTS or Flow=DTR/CTS, then CTS
does not follow RTS in a flow-off condition.

1-28 AT Commands

AT&S, AT*MR (DSR Control)

The A T&S and A T*MR (DSR) commands determine how the modem sets the DSR

TERMINAL OPT’S

DSR

• • •

signal. The modem signals the DTE with the DSR on EIA/TIA 232-D Pin 6
(V.24 Circuit 107).

&S, *MR

Option
Setting

High
(1)

Normal
(3, 4)

1

(2)
DTR AT*MR2 DSR follows DTR.
Drop on Disc

(2)

Sim LL AT*MR4 The same as the DTR setting except DSR is

1

Default with the 326XFAST-SDC Modem

AT Command
Setting Description

AT*MR1
AT&S0

AT*MR0
AT&S1

AT*MR3 The same as the Normal setting except that when

DSR is always on.

DSR is controlled by the modem. DSR is on
when the modem recognizes that it is
communicating with a compatible modem.

a disconnection is initiated from the local end,
DSR is dropped immediately.

dropped when the remote modem requests a
disconnect.

AT Commands 1-29

&T

AT&T (Test)

TEST OPT’S

TEST

• • •

The AT&T (Test) command is used to initiate and terminate tests. See Chapter 4 of
this guide for a complete description of each test.

AT Command

Option Setting

End T est
(all)

LAL 1 Initiates a local analog loopback test.
RDL 6 Initiates a remote digital loopback test.
LDL 3 Initiates a local digital loopback test.
Pattern Initiates an end-to-end pattern test.
LAL Pat 8 Initiates a local analog loopback pattern test.
RDL Pat 7 Initiates a remote digital loopback pattern test.
Busy Out ATH1

Retrain ATO1 Initiates a retrain with the remote modem.
NOTES: (1) For maximum reliability, run the RDL, LDL, and RDL Pat tests at a data rate

of 19.2 kbps or lower. (2) These settings are country-specific. Consult Appendix C,

Setting Description

0 Ends the test currently in progress for each

test listed below (except for the Retrain test).

Makes the modem appear busy to incoming

ATH0

calls. To configure the modem to use the Busy
Out feature, refer to AT
option description in this chapter.

If Busy Out is enabled, ATH0 will disconnect
the busy out condition. If the modem is in
“escape mode” (the modem has transitioned
to command state from the data state—online
or test), the ATH0 command disconnects the
modem. Selecting End Test will also
disconnect the busy out condition.

LT (DTE Pion 25)

*

Country-Specific Information, in the 326X Series Modem User’s Guide for the
settings that are valid in your country .

the modem fallsback to Direct mode (Mode=Direct) to run “on-line” loopback tests. Refer
to “326XFAST Synchronous Data Compression Testing” in Chapter 4, Testing Your
Modem, for additional information.

(3) When operating in the 326XFAST-SDC mode,

1-30 AT Commands

AT&T4, AT&T5 (Accept RDL)

&T4, &T5, &V, *ST

TEST OPT’S

Accept RDL

• • •

can be placed in a remote digital loopback test by a remote modem.

Option
Setting

On
(all)

Off 5 The modem cannot be put into a remote digital

AT Command
Setting Description

4 The local modem can be put into a remote digital

AT&V, AT*ST (Modem Status Display)

The A T&V and A T*ST (Modem Status) commands allow you to view, via your con-

The AT&T4 and A T&T5 (Accept RDL) commands control whether the local modem

DATA 9600 T/D?

DTE 19.2 RELIABL

Option Setting

DTE/DCE 19.2
EC
DC
Tx= kb 0%
Rx= kb 0%
DCD RTS CTS
DSR DTR
AOP DLP ALP
DR=0 TI=0 O D
Display Modem

Id
CQMS

• • •

trol terminal, modem status information in either long or short form, using the

ST and AT&V commands.

AT

*

AT Command
Setting Description

0 Long Form: The A T*ST0 and AT&V commands select the long-form status

snapshot display. This display consists of several screens and provides a
summary of: Operating Status; DTE/DCE Rate/Status; Error correction, Data
Compression Status; EIA/TIA 232-D (CCITT V.24) Signal Status, Disconnect
Reasons; display the modem’s software revision (Display Modem ID); and
CQMS Parameter Status. Also, the long-form snapshot summarizes the settings
of all front panel options and their corresponding AT commands (only the suffix
of the AT command is given; the “AT” is omitted), nonconfiguration (action) AT
commands, and the setting of each S-Register. NOTE: Tx= kb 0% is displayed
only for the 326XFAST-SDC Modem.

1 Short Form: The AT*ST1 and AT&V commands select the short-form status

snapshot display. The short-form display provides a summary of AT command
settings and S-Register values (for a detailed discussion of S-Registers,
see “S-Registers” section in Chapter 5 of the 326X Series Modem User’s Guide.
In short-form, only the suffixes and settings of each nonaction AT command are
shown, and S-Register values are displayed in the following format:

S010:024

This means that S-Register 10 is set to decimal value 24.

loopback test.

loopback test.

The Front P anel. Your front panel provides some or all of the following information:
Operating Status; DTE/DCE Rate/Status; Error Correction, Data Compression, and
Transmit and Receive Throughput and Link Utilization Status; EIA/TIA 232-D
(CCITT V.24) Signal Status; and CQMS Parameter Status.

AT Commands 1-31

&V, *ST

Operating Status Messages

Operating Status messages display the operating status of the modem. NOTE: The
modem automatically displays one of the operating status messages in Table 1-1 if a
front panel key is not pressed within five minutes. The R indicates a restoral
connection and H indicates a hold of the dial line. You can also view Operating
Status messages by pressing until you reach the Home position.

Table 1-1.
Operating Status Messages

Message Description

Data <rate> T/D? The modem is transmitting at <rate> bps.
Data <rate> R T/D? The modem is in dial restoral mode, and transmitting at

<rate> bps.

Data <rate> H T/D? The modem is holding the dial line while it tests the leased

line, and transmitting at <rate> bps.
Dialing T/D? The modem is dialing a telephone number.
Disconnect T/D? The modem is not connected to the telephone line.
LAL <rate> T/D? The modem is in a local analog loopback test, at <rate> bps.
LAL Training T/D? The modem is executing a training sequence for a local ana-

log loopback test.
Test <rate> T/D? The modem is running a test at <rate> bps.
Bad LAL T/D? The modem failed a local analog loopback test.
Busyout T/D? The modem appears busy to incoming calls.
Dial Wait T/D? The modem is waiting before dialing a number.
Link Wait T/D? A call attempt failed and the modem is waiting before dialing

the linked telephone number.
Redial Wait T/D? A call attempt failed and the modem is waiting the specified

interval before redialing.
Callbk Wait T/D? The modem is waiting to call back another modem.
Ranging T/D? The modem is connected to the telephone line and attempting

first training sequence with the remote modem.
Training T/D? The modem is training.
Retraining T/D? The remote modem has requested a retraining sequence.
Synchronizing T/D? A handshake has failed. The modem is pausing before

attempting to resynchronize by retraining.
Tone Detect T/D? The modem is waiting for access security tones from the

remote modem.
Disc Wait T/D? The modem is disconnecting.
Disc/Rx Wait T/D? The modem is performing a receive buffer delay.
Disc Tx Wait T/D? The modem is performing a transmit buffer delay.
Off Hook T/D? The modem is off hook.
WAIT <rate> T/D? The modem is negotiating a reliable connection.

1-32 AT Commands

&V, *ST

The reference to <rate> in Table 1-1 refers to the range of DCE data rates that are
supported by the 326X Series Modem. The following data rates may be displayed:

1

24,000

1

21,600

1

19,200

1

16,800

1

14,400

1

12,000

2

9600U

1

9600

1

7200
4800
2400

1

The modem is transmitting at a specified data rate using trellis-coded modulation.

2

The modem is transmitting at 9600 bps without using trellis-coded modulation.

3

The modem is transmitting at 300 bps using a frequency-shift keyed (FSK) modulation

mode.

1200
300

3

AT Commands 1-33

&V, *ST

DTE Rate/Status Summary

Pressing from the Operating Status display brings you to the DTE Rate/Status
line. The DTE rate represents the speed at which the local modem and DTE are
communicating. The following definitions apply:

DTE Rate/
Display DTE-to-Modem Rate (bps)

Ext When Clock=External, Ext is displayed indicating the modem is

accepting clock from the DTE. NOTE: Ext is displayed when the
modem is configured for synchronous operation (direct synchronous
mode or SDC mode).

128.0 128, 000

115.2 115, 200

96.0 96, 000

76.8 76, 800

72.0 72, 000

64.0 64, 000

57.6 57, 600

56.0 56, 000

48.0 48, 000

38.4 38, 400

28.8 28, 800

26.4 26, 400

24.0 24, 000

21.6 21, 600

19.2 19, 200

16.8 16, 800

14.4 14, 400

12.0 12, 000

9.6 9600

7.2 7200

4.8 4800

2.4 2400

1.2 1200
.3 300

1-34 AT Commands

&V, *ST

The DTE Status IDs are explained below.

Error-Correction
Status Description

RELIABL The modem is online and operating in an asynchronous error-

correcting data transfer mode.

SYNREL The modem is online and operating in a synchronous error-

correcting data transfer mode (SDC Mode)
DIRECT The modem is online and operating in the direct data transfer mode.
NORMAL The modem is online and operating in the normal data transfer

mode.
COMMAND The modem is in command mode, and does not have a connection.
FAILREL Reliable negotiation failed.
ATTEMPT The modem is attempting to establish a reliable connection.

Error-Correction and Data-Compression Status

Pressing from the DTE Status display brings you to the Error Correction and
Data Compression Status display. The following definitions apply.

EC Message Description

LM The modems are connected and using LAPM error correction.
M1 – M4 The modems are connected and using MNP error-correction level 1, 2, 3,

or 4.

NONE No error correction is being used.

DC Message Description

V42bis The modems are connected and using V.42 bis data compression.
MNP5 The modems are connected and using MNP Level 5 error correction.
NONE No data compression is being used.

AT Commands 1-35

&V, *ST

Transmit and Receive Throughput and Link Utilization
Status Display

Pressing again brings you to the Transmit (Tx) and Receive (Rx) Throughput and
Link Utilization Status displays:

Tx=xxx.x kb yyy%
Rx=xxx.x kb yyy%

These displays provide the modem’s throughput rate (in kilobits) and the total
percent of the analog channel currently being used for transmitting and receiving
data.

The throughput rate is a running average of the data bit rate through the modem
based on the most recent data transmitted to and received from the DTE.

Link utilization is based on the amount of data traffic transmitted and received over
the analog channel. Link utilization is displayed in terms of the percentage of the
channel that is being used.

Upon disconnection, the Transmit and Receive Throughput and Link Utilization
Status display shows the throughput and link utilization at the time of disconnection.

These displays help to identify where delays in data transmission exist, whether
within the modem or whether an insufficient amount of data is available for
transmission. For example, if the display indicates a 40 kb throughput, with a 10%
link utilization, then there is not enough data available for transmission. Alternately,
if a 40 kb throughput is displayed, with 100% link utilization, then data throughput
has been optimized.

NOTE: If Mode=Direct (AT

SM), these displays appear blank.

*

1-36 AT Commands

EIA/TIA 232-D (CCITT V.24) Signal Status

Pressing from the Throughput Status brings you to the EIA/TIA 232-D (CCITT
V.24) Signal Status lines (see Table 1-2 for definitions). NOTE: To the right of each
EIA/TIA signal, in the front panel display window, is a box symbol. If the box is
filled in, it indicates that the signal is on. If the box is empty, the signal is off.

Table 1-2.
EIA/TIA 232-D (CCITT V.24) Signal Status Messages

Abbreviation Signal Name Description

DCD Data Carrier

Detect

RTS Request to Send On. The DTE is requesting to send data to the

CTS Clear to Send On. The modem is ready to accept data from the

DSR Data Set Ready On. The modem is ready to exchange data.
DTR Data T erminal

Ready

AOP Answer/Originate On. The DTE is requesting the modem to enter

DLP Remote Digital

Loopback T est

ALP Local Analog

Loopback T est

On. The modem is receiving carrier from the remote
modem.

modem.

DTE.

On. The DTE is ready to exchange data.

answer mode.
On. The DTE is requesting a remote digital

loopback test (V.24 Circuit 140, Pin 21).
On. The DTE is requesting a local analog loopback

test (V.24 Circuit 141, Pin 18).

&V, *ST

AT Commands 1-37

&V, *ST

Status Summary Line

Pressing from the EIA/TIA 232-D Signal Status display brings you to the Status
Summary Line (see T able 1-3 for definitions). Table 1-3 displays disconnect reasons,
test indicator, answer or originate, and dial and leased line status.

Table 1-3.
Status Summary Line

Message Definition

DR Disconnect Reason. Indicates reason for last disconnect or failed call.

1 = DTR dropped
2 = ATH command issued
3 = Remote modem disconnected
4 = Manager request
5 = Configuration change caused disconnect
6 = Restoral – Manager
7 = End Restoral – Manager
8 = MI/MIC signal transition to off
9 = Talk/Data (at the Home position) pushed
10 = DTR end restoral

11 = End Restoral – 116
12 = Offline test initiated
13 = Training failure
14 = Security failure – Invalid Password
15 = Security callback
16 = End Restoral – Auto
17 = Error correction link
18 = Already connected
19 = Dial aborted
20 = Busy tone detected

21 = No dial tone detected
22 = Longspace detected
23 = Dial aborted due to an incoming call
24 = DTR not in proper state
25 = Number on Forbidden or Delayed list
26 = Retrain threshold exceeded
27 = Answer/Originate mode changed (Pin 11)
28 = No stored number to dial
29 = Test in progress
30 = Callback in progress

1-38 AT Commands

&V, *ST

Table 1-3.
Status Summary Line (Continued)

Message Definition

31 = FSK and synchronous data modes incompatible
32 = Semicolon detected in dial string
33 = Answer-back tone detect timeout, no ringback tone
34 = Answer-back tone detect timeout, ringback tone detected
35 = Answer-back tone detect timeout, no call progress
36 = Answer-back tone detect timeout, no answer
37 = Answer-back tone detect timeout, busy after ringback
38 = Denied manager down
39 = Error-correction link retransmission limit
40 = Error-correction link remote requested

41 = Error-correction link no valid packet received
42 = Error-correction link establishment error
43 = Error-correction link accept or timeout
44 = Error-correction link negotiation failure
45 = Error-correction link protocol violation

46 = Error-correction link bad parameter
47 = Error-correction link data compression error
48 = FSK and reliable data modes not valid
49 = Restoral – DTR
50 = Restoral – Circuit 116

51 = Restoral – Auto
52 = Restoral – Answer
53 = Restoral – Talk/Data
54 = End Restoral – Talk/Data
55 = End Restoral – Dial to Lease Timeout
56 = Lease Line Test
57 = Lease Line Test – Manager
58 = Lease Line Test Failed
59 = External Option Set selected
60 = Option Set selected – ATZ

AT Commands 1-39

&V, *ST

Table 1-3.
Status Summary Line (Continued)

Message Definition

61 = Lease Line Test Passed
62 = Security – No Callback Number provided
63 = Security Failure – Manager timeout
64 = Security Failure – Invalid Callback Number
65 = Security Failure – Interdigit timeout
66 = DTE Inactive
67 = Restoral – ACU
68 = End Restoral – ACU
69 = Restoral – DTR ACU
70 = End Restoral – DTR ACU

71 = Restoral – ACU.116
72 = End Restoral – ACU.116
73 = LPDA2 Disconnect
74 = Remote disconnected without sending PSTN
75 = Configuration change cause disconnect
76 = Retraining time exceeded
77 = Remote Access Reset

TI Test Indicator. The number displayed after TI tells you which test is in

progress. The numbers correspond to the following messages:
0 = No Test/End Test
1 = Local Digital Loopback Test
2 = Remote Digital Loopback Test
3 = Local Analog Loopback Test
4 = Reserved
5 = Busy Out
6 = Local Analog Loopback Pattern Test
7 = Remote Digital Loopback Pattern Test
8 = Pattern Test
9 = Retrain

A or O Answer/Originate

A = Modem is in Answer mode
O = Modem is in Originate mode

D or L Dial/Leased

D = Modem is using a dial telephone line
L = Modem is using a leased telephone line

1-40 AT Commands

&V, *ST

Display Modem ID

This display enables you to determine your unit’s current revision of software.
To display the software revision level:

1) Step across the Status/Option Sets/Dialing Menu by pressing until you
reach the Operating Status Display. A typical Operating Status display is:

DTE 19.2 RELIABL

2) Press until you see

Display Modem ID

3) Press . The modem displays

SWPart=xxxxxxxx

4) The rightmost two digits indicate the software revision level.

Alternately, you can enter

AT&I0

from the control terminal. The terminal displays the 8-digit software part number:

xxxxxxxx

the software revision number is indicated by the rightmost two digits.

CQMS Parameter Status

Pressing , then twice from the Status Summary Line displays CQMS Parameter
Status. Pressing scrolls you through the CQMS Parameter Status displays (see
Table 1-4 for definitions that apply).

CQMS Status information is important in order to make proper operating decisions.
Dial modem data traffic typically travels across a mix of facilities provided by local
and long distance carriers. This fact has significant implications on how you can
troubleshoot apparent line problems.

The entry point into the carrier network is the (switched dial) line sent from the local
carrier. Standard lines are typically used for voice and telephone traffic. While voice­grade lines can be used for data traffic, it is better to contract for data-quality lines.
Data-quality lines offer improved line quality specifications guaranteed by the local
carrier.

When one dial modem connects to another modem, the connection spans different
telephone facilities. The connection between the dialing modem and the telephone
company central office (CO) is referred to as the local loop. COs are connected by
intra-office exchange connections or by inter-LATA long distance connections,
depending on the distance of the call. At the remote answering modem, there is a
central office-to-modem remote local loop connection.

AT Commands 1-41

&V, *ST

For a given dial modem dialing various remote modems, the only connection that
remains constant from call to call is the local loop. When one modem dials another
modem multiple times, the local and remote local loops remain the same. All other
connections are likely to vary from call to call.

Good quality on one call is no guarantee of equal quality on the next call, even if the
call is to the same location. Poor quality for one call does not mean the line of the
next call will be equally poor.

When monitoring line quality , it is important to spot trends and persistent conditions.
Examples are provided below.

• Consistent poor connections for all local calls can indicate poor quality on the
local loop. Signs of this are consistent V.32 bis calls which cannot maintain

14.4 kbps speeds. Persistent signal-to-noise ratios above a baseline established
at the time of installation are indications of poor line quality.

• A sudden shift from generally good local calls to generally poor local calls can
indicate that the local telco has moved the local loop, and the quality of the new
loop is inferior.

• Consistently poor connections to one destination can indicate poor quality at
the remote local loop. Signs of this are consistent V.32 bis calls which cannot
maintain 14.4 kbps speeds.

In all cases, it is important that you begin operation by obtaining a baseline of
“normal” good quality service of typical connections. With this, deviations from the
normal can be spotted. Also, to help you locate persistent trends, use CQMS value
information in conjunction with current and historic network information. Once the
baseline is determined for your network, the thresholds for each parameter can be
used to identify abnormal line performance. For example, if all local calls connect as
expected, yet the long distance calls show a higher rate of errors, the CO-to-CO or
remote local loop connections may be degraded.

The 326X Series CQMS parameters measure end-to-end performance, monitoring
the transmission signal for noise and other distortions (non-linear and transient
impairments are not measured by the 326X. This information is continuously
updated to reflect current line conditions for both local and remote devices.

NOTES:

1) The CQMS values are estimates of line parameters and expected performance,
to be used for planning only, and are not intended to be warranties of product
performance.

2) If your modem is not currently connected to another modem, the CQMS
values that are displayed are of the last call.

1-42 AT Commands

&V, *ST

Table 1-4.
CQMS Parameters

Front
Panel
Display Description

PhaseJitter Measured in degrees, phase jitter is a continuous “fluttering” of the

incoming analog signal from either its timing signal or from the referenced
phase of the main data carrying signal. The phase jitter parameter measures
the change in phase of the analog signal from the referenced phase of the
main data-carrying signal. The shift in phase is often caused by alternating
current components. Modulation of the carrier with another signal during
transmission causes the change of phase or frequency . Range: 0 - 45 degrees,
with 0 meaning there is no phase jitter.

Frq Offset Measured in Hz, frequency offset is a measure of the incoming signal's

deviation from normal carrier frequency. This condition is caused by two
data carrier systems being out of tune with each other. Frequency offset is
also called frequency shift. All operating modes cancel out any frequency
offset on the line. For example, if 1 Hz of frequenc y of fset is detected on the
line, all received signals are adjusted by 1 Hz.

Tx Level Measured in dBm, transmit level is a measure of the power of the

transmitted signal. Transmit level displays the strength of the signal the
326X Series is transmitting (in decibels, relative to 1 mW). It measures the
power level of the signal leaving the device's transmitter.

Rx Level Measured in dBm, receive level is a measure of the power of the received

signal. This parameter displays the strength of the signal the 326X Series is
receiving (in decibels, relative to 1 mW). Receive level measures the power
level of the signal entering the device's receiver. Acceptable receive level
varies with the carrier detect selection.

Retrains This parameter displays the number of training sequences that have occurred

between the local and remote device for each single line connection. The
326X Series may retrain due to a user-initiated retrain request using the Test
option, a user-initiated retrain request using the Max Rate and Min Rate
options, and a modem-initiated retrain request, due to poor signal quality, to
attempt to relearn the channel or fallback in data rate by enabling ARS if
necessary. A retrain is counted if it is initiated locally or remotely, i.e., both
the local and remote 326X Series retrain counters are incremented.

Note that the retrain counter for automatic restoral operation is a separate,
undisplayed counter. The restoral retrain counter is a mo ving windo w, based
on the settings of the Leased to Dial option.

Echo Delay Measured in milliseconds (from 1 to 9999 ms), this is the far-end echo

round-trip delay time. This value is displayed only when the C.Fast, V.32
bis, or V.32 modulation mode is being used. Otherwise, the displayed value
is zero. Echo delay displays how far away in time the far-end echo is, i.e.,
the round trip delay of the physical link layer.

AT Commands 1-43

&V, *ST

Table 1-4.
CQMS Parameters (Continued)

Front
Panel
Display Description

Far Echo Lvl Measured in decibels (from -6 to -72 dBm), this is the strength of the echo

signal generated between the local modem and the remote modem CO
connection. This value is displayed only when the C.Fast, V.32 bis or V.32
modulation mode is being used. Otherwise, the displayed value is zero.
NOTE: If the far end echo level is 35 dB below its receive level, the Phase
Roll CQMS parameter has no meaning.

Nr Echo Lvl Measured in decibels (from -6 to -72 dBm), this is the strength of the echo

signal generated on the local loop (i.e., between the local modem and the
local CO). This value is displayed only when the C.Fast, V.32 bis, or V.32
modulation mode is being used. Otherwise, the displayed value is zero.

Phase Roll Measured in Hz (from 0.0 to 9.4 Hz), this is a measure of the frequency

offset of the echo. This value is displayed only when the C.Fast, V.32 bis, or
V.32 modulation mode is being used. Otherwise, the displayed value is zero.
It is the difference in the transmit and receive path's frequency offset.
NOTE: If the value of the far end echo level parameter is 35 dB below its
receive level, Phase Roll has no meaning.

Eqlzr SNR Equalizer Signal-to-Noise ratio displays the Signal-To-Noise Ratio (SNR)

measured in decibels (from 0 dBm to 38 dBm). The SNR measures the
signal strength compared to the signal dispersion caused by circuit noise.
Circuit noise is any random signal disturbances in a communications link,
such as electromagnetic interference, which tend to degrade line
performance.
This signal is measured after it has passed through the receiver's equalizer. It
is not the SNR of the telephone line, since the equalizer reduces the effects
of certain types of channel distortion.
Determination of a good or bad SNR varies depending on modulation mode
and data rate, in addition to one's definition of good and bad (specifically,
which BER is acceptable for a specific application).

SQ Signal Quality displays the relative quality of the received signal (0-9),

where Good=9, and Poor=0. Signal quality is a single representation of a
variety of line impairments.
An approximate BER to SQ table follows, independent of the data rate.
SQ<3, the bit error rate is approximately greater than (worse than) 10
SQ=3, the bit error rate is approximately 10
SQ=4, the bit error rate is approximately 10
SQ>4, the bit error rate is approximately less than (better than) 10

EP Error Probability displays the probability of an error in the data stream (in

percent). Error probability, which acts as a confirmation of line
deterioration, increases as the amount of distortion increases. The
percentage increases as the amount of noise and/or distortion increases. An
error probability value between 0% and 20% is considered good; a value
between 21% and 40% is considered fair; and a value between 41% and 70%
is representative of marginal line quality.

-2

-4

-2

-5

1-44 AT Commands

AT&W (Save Changes: Creating New Option Sets)

&W

DATA 9600 T/D?

Save Changes

• • •

The AT&W (Save Changes) command saves an option set that you have created in
the modem's nonvolatile memory. The first part of this section describes how to save
an option set using the AT&W command; the second part describes how to save an
option set from your modem's front panel.

Option
Setting

1
(all)

2 2 Save as Option Set 2
3 3 Save as Option Set 3
4 4 Save as Option Set 4

AT Command
Setting Description

0, 1 Save as Option Set 1

When using the AT command or the front panel to select options, if you do not save
your modifications, the modem does not enter them into nonvolatile memory.
However, the modem operates according to these modifications until you do one of
the following:

• Choose another option set using the Select Options feature, the ATZ command,
or A T&D3 command.

• Reinitialize the modem's memory using the Reinit Memory? option or the
AT&F command.

• Power down the modem.

If you do want to save messages, do not turn off modem power until the “Save
Completed!” message appears. Any modifications that you make are not placed in
nonvolatile memory until “Save Completed!” appears.

The AT&W Command

The AT&W command allows you to create customized option sets.
To create a customized option set using the AT&W command:

1) Using the ATZn command, select the option set that most closely suits your
application. The option set number you want to modify is represented by the
“n.”

2) Use the AT commands described in this chapter to change the setting of each
option you want to modify. For example, to change RTS/CTS delay from its
delay time according to S-Register 26, to a new setting of 15 ms, enter:

AT*DL1<CR>

The modem responds with:

OK

AT Commands 1-45

&W

3) Once you have made all the changes to create your option set, enter the
AT&Wn command. The “n” that you choose specifies the address (the option
set) where the new customized option set is stored.

The front panel displays:

Saving Options

4) After a few seconds, your modifications are stored in the modem's nonv olatile
memory, and the modem front panel displays:

Save Completed!

The new customized option set you have created replaces in nonvolatile memory the
option set previously stored in that option set address.

The Front Panel

To create a customized option set:

1) Using the Select Options function, select the option set that most closely suits
your application (see Chapter 4, Configuring Y our Modem, of the 326X Series
Modem User’s Guide for an in-depth discussion of option sets).

2) Display the individual option(s) you want to modify using and . For
example, if you want to change the Max Rate setting from 2400 to 7200,
display:

Max Rate:7200

3) Press . The display flashes three times and the colon changes to an equal
sign. The new option is now temporarily saved and the modem displays:

Max Rate=7200

4) Step across the Status/Option Sets/Dialing menu by pressing until you see:

Save Changes=n

5) Use the key to display the option set number where you want the changes
saved, and then press . The modem displays:

Saving Options

6) After a few seconds, the modifications are stored in the modem's nonvolatile
memory, and the modem displays:

Save Completed!

1-46 AT Commands

AT&X (Clock)

&X, &Y

MODULATION OPT’S

Clock

The AT&X (Clock) command sets modem timing and applies to synchronous

• • •

applications only. For most dial applications, use internal timing. If you change this
option during a connection, the change takes effect immediately.

Option
Setting

Internal
(all)

External

1

(2)

Loopback 2 Loopback Transmitter Timing. The modem uses

1

Default with 326XFAST-SDC Modem.

AT Command
Setting Description

0 Internal Transmitter T iming. The modem uses

Internal clocking: timing signals are passed on
EIA/TIA 232-D Pin 15 (V.24 Circuit 114).
Internal timing is used for most applications.

1 External Transmitter T iming. The modem uses

External timing: timing signals are passed on
EIA/TIA 232-D Pin 24 (V.24 Circuit 113).

Loopback timing: timing signals are passed on
EIA/TIA 232-D Pin 17 (V.24 Circuit 115).
NOTE: This selection is not available if you are
operating in the 326XFAST Synchronous Data
Compression mode. If you select Loopback with
synchronous data compression enabled, the
modem uses Internal timing instead.

AT&Y (Power Up in Option Set)

DATA 9600 T/D?

• • •

Power Up In

The AT&Y (Power Up In) command assigns the option set your modem uses when
you power up. It is also used when you are resetting the modem memory (AT&D3).

Option
Setting

Old
(all)

1 – 4 1 – 4 When you turn on the modem, it automatically

AT Command
Setting Description

0 When you turn on the modem, it automatically

uses the last saved option set that was selected
when the modem was turned off.

uses the option set corresponding to the number
selected.

AT Commands 1-47

&Z, *CN

AT&Z, AT*CN (Enter Telephone Numbers)

DATA 9600 T/D?

• • •

Enter Phone #

The A T&Z and A T*CN (Enter Phone #) commands store a telephone number
(up to 50 characters) in one of the modem's nine “telephone book” addresses.

Option
Setting

1 – 9 1 – 9 Your modem stores the telephone number in the

The AT&Z or A T

To store a telephone number in one of the modem's nine telephone book addresses,
enter the AT&Z or AT
and the telephone number you want to store. For example, to store the number
1-222-555-4444 in memory location 3, enter:

AT*CN3,12225554444<CR>

If you enter the AT&Z or AT*CN command without specifying a memory location,
the modem stores the number in address 1. If no telephone number follows the

CN or AT&Z command, the specified memory location's telephone number is

AT

*

deleted. Therefore, if you enter:

AT*CN<CR>

or

AT&Z<CR>

AT Command
Setting Description

designated telephone book memory location.

CN Command

*

CN command, the telephone book address (1-9), a comma,

*

the telephone number stored in memory location 1 is deleted.

The Front Panel

See the "Performing Numeric Entry" section in Chapter 2 for details on how to use
numeric entry.

See “Dial Modifiers for Special Dialing Requirements” in Appendix A of the 326X
Series modem User’s Guide for a description of allowable characters.

1-48 AT Commands

AT* Commands

The following sections describe Motorola-enhanced AT commands, which begin
with A T

AT*AA (Answer)

*

AA

*

.

ACU OPT’S

Answer

• • •

The A T*AA (Answer) command controls whether the modem answers calls
automatically or manually.

Option
Setting

Manual 0 An incoming call must be answered manually.
Ring #1 1 The modem automatically answers an incoming

Ring #2 2 The modem automatically answers an incoming

Ring #4 3 The modem automatically answers an incoming

Ring #8 4 The modem automatically answers an incoming

Using S0 5 The modem answers an incoming call according

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

call after the first ring.

call after the second ring.

call after the fourth ring.

call after the eighth ring.

to the setting of S-Register S0.

AT Commands 1-49

AP

*

AT*AP (Adaptive Rate)

MODULATION OPT’S

Adaptive Rate

The A T*AP (Adaptive Rate) command determines whether the adapti ve rate feature

• • •

is used.
The Adaptive Rate option, when enabled, selects the optimum data rate on the first

connection, and then constantly monitors signal quality and changes speeds as
necessary to optimize user data throughput. Based on the signal quality, the modem
shifts speeds up or down, to choose the appropriate transmission rate to minimize the
error rate and maximize throughput and efficiency.

ARS operates in the following modulation modes, and corresponding data rates:

• C.Fast: 24.0, 21.6, 19.2, 16.8, 14.4, 12.0, and 9.6 kbps

• V.32 bis: 14.4, 12.0, 9.6, and 7.2 kbps

• V.32/V.32 Uncoded: 9.6 and 4.8 kbps

• V.22: 2.4 and 1.2 kbps

When line conditions deteriorate (i.e., poor signal quality), the modem retrains and
determines the rate that the line can support. Under poor line conditions, the modem
may fall back by more than one rate. For example, if operating at a data rate of 24.0
kbps, under poor line conditions, the modem may retrain to 19.2 kbps instead of 21.6
kbps. ARS fallback is based on the High BER setting of the AT
option. When the modem falls back, a longer retrain occurs.

RT (Retrain)

*

When line conditions improve, based upon the identification of good signal quality,
the modem falls forward (increases the data rate) one rate at a time. The minimum
time required to fall forward is 4 minutes. When the modem falls forward, a quick
retrain occurs.

NOTE: The AT
BER) if you use the adaptive rate setting.

The 326XFAST/326XFAST -SDC product uses a line probing feature during the initial
training sequence. Line probing selects the maximum data rate that the line can
support, as well as the optimal baud rate and carrier frequency at which to run.
Due to this, while operating in C.Fast modulation modes, the 326X Series Modem
may require a longer training sequence.

RT (Retrain) command must be enabled (set to Low BER or High

*

1-50 AT Commands

AP, *AS

*

If you choose to operate the 326X Series Modem in the C.Fast modulation mode
with the ARS option (AT
conditions) retrain at the maximum data rate. If the line probe feature selects a baud
rate that cannot support the maximum data rate, the modem will retrain and establish
the connection at the maximum data rate allowable by the baud rate that the line
probe feature selected.

NOTE: When external timing is selected, configure the modem so that the minimum
rate is equal to the maximum rate. This will force the selection of the data rate to the
rate you selected.

AP) disabled, the modem may not (depending on line

*

Option
Setting

On
(all)

Off 0 The modem does not use the adaptive rate

AT Command
Setting Description

1 The modem continuously monitors the signal

AT*AS (Answer in Restoral)

The A T*AS (Ans Rest) command controls whether the modem answers a call on the

RESTORAL OPT’S

• • •

Ans Rest

dial line while connected to the leased line.

Option
Setting

LL Fail
(all)

Always 1 A dial call is always answered. As soon as the

AT Command
Setting Description

0 When connected on the leased line, the modem

quality of the telephone line and negotiates the
highest possible rate within one of the following
modulation modes: C.Fast, V.32 bis, V.32, or
V.22 bis. You must enable the AT*RT (Retrain)
command if you plan to use the adaptive rate
setting. Close rear panel Switch 1 (down) so that
the modem can inform the terminal of rate
changes (see Table 2-2, Rear Panel Switches, in
Chapter 2, Installing Your Modem in the 326X
Series Modem User’s Guide).

feature.

answers an incoming call only if the leased line
fails.

dial call is answered, the leased line connection
is dropped (with auto-answering, the leased line
is dropped after the correct number of rings). If
training on the dial line fails, the modem returns
to the leased line.

AT Commands 1-51

AY, *BD

*

AT*AY (Auto Type)

The A T*AY (Auto Type) command determines how the modem negotiates

MODULATION OPT’S

Auto Type

modulation modes with the calling modem if it is answering calls, and one of the

• • •

“Auto” modulation modes (C.Fast Auto, V32bis Auto or Auto V32) is selected.

Option
Setting

Codex 1 During answer-back tone, the modem attempts to

CCITT (all) 0 The modem operates in accordance with Annex

AT Command
Setting Description

negotiate a connection in the V.32 modulation
mode. After sending answer-back tone, the
modem continues to attempt to negotiate a
connection in the V.32 modulation mode. If
unsuccessful, the modem tries to negotiate a
connection in the V.22 bis modulation mode.
NOTE: Use this setting if the calling modem is a
Motorola 2264 or 2266 Modem with software
revision 3.0 or below.

A (Automode) to the V.32 bis specification.
During answer-back tone, the modem attempts to
negotiate a connection in the V.32 modulation
mode. As soon as answer-back tone ends, if a
V.32 tone has not been detected during ABT, the
modem attempts to negotiate a connection in the
V.22 bis modulation mode.

AT*BD (Blind Dial)

The A T*BD (Blind Dial) command determines the time interval that the modem

DIALING OPT’S

• • •

Blind Dial

waits before dialing. Once the time interval has expired, the modem dials. It does not
wait for a dial tone.

Option
Setting

2 0 The modem waits 2 seconds before dialing.
4 1 The modem waits 4 seconds before dialing.
S6 2 The modem waits the amount of time specified

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

by S-Register 6 before dialing.

1-52 AT Commands

AT*BK (Break Handling)

The A T*BK (Break) command controls how the modem handles the break signal in

EC/DC OPT’S

Break

the reliable and auto-reliable data transfer modes. During a Normal mode

• • •

connection, the modem handles breaks as standard, regardless of this option setting.
During a Reliable, Auto-Reliable, or Speed Auto-Reliable connection, breaks are
handled according to the option setting of the modem where the break originated.
Break signals are sent to the DTE for a duration of one second.

BK, *CA

*

Option
Setting

Destruct
(all)

Expedited 1 The modem uses nondestructive and expedited break

Standard 2 The modem uses standard break handling. It passes the break

AT Command
Setting Description

0 The modem uses destructive and expedited break handling.

It passes the break to the remote site immediately and deletes
all data from its buffers. NOTE: Destructive breaks
reinitialize data compression tables for MNP-5 and V.42 bis.

handling. It passes the break to the remote site immediately
without deleting data from its buffers.

to the remote site in sequence with any transmit data from its
buffers.

AT*CA (Answer/Originate Mode)

The A T*CA (Mode) command determines whether the modem operates as an

MODULATION OPT’S

Mode

answer or originating modem. Use this option in manual answer, manual dial, leased

• • •

line restoral or leased line applications where one modem is set to originate and the
other to answer. If you change this option during a connection, it does not tak e ef fect
until the next call. All option settings are overridden when dialing or answering an
incoming call. NOTE: With a leased-line connection, the change takes effect
immediately.

Option
Setting

Originate
(1, 3)

Answer
(2, 4)

External 2 External. The signal from the DTE on EIA/TIA 232-D Pin 11

Auto A
in O

AT Command
Setting Description

0 Originate. The modem operates as an originating modem in a

manual answer/dial application.

1 Answer. The modem operates as an answer modem in a

manual answer/dial application.

determines whether the modem is in answer or originate
mode. If the signal is off, the modem is in originate mode; if
the signal is on, the modem is in answer mode.

3 Auto answer in originate. The modem configures itself as an

originating modem after auto-answering a call. In leased-line
operation, the modem functions as if it is set to originate
calls. NOTE: The functions provided by this setting only
apply when your modem auto-answers.

AT Commands 1-53

CD, *CM, *CN, &Z, *CT, &R

*

AT*CD (DCD Loss Disconnect)

The A T*CD (DCD Loss Dis) command determines how long the modem waits

TERMINAL OPT’S

DCD Loss Dis

• • •

before it disconnects due to loss of carrier (DCD). If the S10 setting is selected and
set to 255 or Off, the modem attempts to retrain indefinitely.

For C.Fast, V.32 bis, and V.32, the AT
how long the modem waits for a retrain to complete. For the 3 and 7 seconds
selections, the time is forced to 15 seconds. If the S10 setting is selected and set to
255 or Off, the modem never disconnects due to a carrier loss.

CD (DCD Loss Dis) command determines

*

Option
Setting

Off 0 The modem will not disconnect due to loss of carrier.
3s 1 The modem hangs up if it loses carrier for 3 seconds.
7s 2 The modem hangs up if it loses carrier for 7 seconds.
S10

(all)

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

3 The modem checks the value stored in S-Register 10 to

AT*CM (Connect Message)

The A T*CM command allows you to select whether you want to display the current

ACU OPT’S

• • •

Con Msg

DTE or DCE rate after the connect message. Refer to “DTE Rate/Status Summary”
section on page 1-34 for possible DTE/DCE rates.

Option
Setting

DTE Rate
(default)

DCE Rate CM1 Selecting DCE Rate results in the current DCE rate being

AT Command
Setting Description

CM0 Selecting DTE Rate results in the current DTE rate being

determine when it disconnects due to loss of carrier. See
“S-Registers” in Chapter 5 of the 326X Series Modem
User’s Guide, for more information about S-Register 10.

displayed on your terminal after the connect message.

displayed on your terminal after the connect message.

AT*CN, AT&Z (Entering Telephone Numbers)

See the AT&Z command description.

AT*CT, AT&R (C, TS)

See the AT&R command description.

1-54 AT Commands

AT*DA (Default Dialing)

The A T*DA (Default Dialing) command controls the Default Dial feature. When

ACU OPT’S

• • •

Default Dial

the Default Dial option is enabled, the modem dials the telephone number in the
specified address if one of the following conditions occurs. This option also
determines the telephone number dialed during restoral.

DA

*

Option
Setting

Off
(1, 2, 3, 4 D)

1 – 9
(4L)

1

(2, 3)

1

Default with the 326XFAST-SDC Modem

AT Command
Setting Description

0 The default dial feature is disabled.

1 – 9 The modem direct dials the telephone number

stored in the memory address selected (memory
addresses 1 – 9) when one of the following
conditions occurs:

• The DTR option in the modem is set to

108.1 or Tail, and the DTE turns the DTR
signal from off to on.

• The DTR option in the modem is set to

108.2, Esc, Discon, Reset, or High, the DTR
signal is on, and either the front panel Talk/
Data key ( at the Home position) is
pressed, or control of the dial is switched to
the modem with an exclusion key telephone.

• ACU Select=AT, AT Form=DTR Dial, and
the DTR signal transitions from off to on.

AT Commands 1-55

DB

*

AT*DB (Buffer Delay)

The A T*DB (Delay) command allows you to configure the modem for a disconnect

EC/DC OPT’S

• • •

Delay

delay to provide time for clearing buffers. S-Register 38 determines how long the
modem processes buffered data when a disconnect is initiated. The range for
S-Register 38 is between 0 and 255.

The disconnect buffer delay feature applies when data is transmitted from DTE to
DCE or from DCE to DTE. When this feature is enabled, depending on which
disconnect type you have selected, the modem delays to clear its TX or RX buffer.

The TX buffer delay applies to the following disconnect types: DTR, ATH, LPDA2.
The following commands apply to the termination of connections restored on the
dial line: DTR, ATH, and 116.

The RX buffer delay applies to the following disconnect types: error correction link
disconnects, PSTN cleardowns, and Longspace. When a delay is in progress, talk/
data, as well as a disconnect in the opposite direction, causes an immediate
disconnect.

NOTES:

1) When the modem is configured for Mode=Direct, there is no buffering of data.

2) This option does not apply when the modem is in a test mode.

Option
Setting

Off
(all)

Buf Or S38
(3)1

Buf & S38 AT*DB2 This setting prevents the timer from starting until either

S38 AT*DB3 This setting allows the timer to start immediately upon

1

Default with the 326XFAST-SDC Modem

AT Command
Setting Description

AT*DB The Off setting disables the Delay option.

AT*DB1 This setting starts the buffer delay timer immediately

upon detection of the disconnect request. When the timer
is operating, the modem continues to process either the
transmit or receive buf fers. The modem disconnects when
the buffers are empty or the timer expires, whichever
occurs first. NOTE: When the modem is set for Direct
mode, no buffering of data exists and the disconnect is
immediate.

the transmit or receive buffers have emptied. The modem
disconnects. Once the timer expires, when the modem is
set to Direct mode, data is not buffered and the timer
starts immediately.

detection of the disconnect request. This disconnect
request continues to process either its transmit or receive
buffers. The modem disconnects when the timer expires,
regardless of the state of the buffers. NOTE: When the
modem is set for Direct mode, no buffering of data exists.
However, the modem delays a disconnect until the timer
expires.

1-56 AT Commands

AT*DC (Data Compression)

The A T*DC (DC) command determines the data-compression technique used by

EC/DC OPT’S

DC

• • •

your modem. NOTE: This option does not apply when the 326XFAST-SDC Modem
is configured for synchronous data compression operation.

DC, *DD

*

Option
Setting

Disable 0 Data compression is not attempted.
Enable

(all)

AT*DD (Dial Wait)

The A T*DD (Dial Wait) command instructs the modem to stop and wait for a dial

DIALING OPT’S

• • •

Dial Wait

tone. The modifiers are as follows:

•W

•w

•:

AT Command
Setting Description

1 Data compression is attempted.

If your modem is using LAPM error correction, it uses
V.42 bis data compression if DC=Enabled. NOTE: In an
application with 326XFAST Synchronous Data
Compression enabled, LAPM error correction and V.42
bis data compression only are used.

If your modem is using MNP error correction, it attempts
to negotiate V.42 bis and MNP-5 data compression with
the remote modem.

Depending on which data compression type can be
accommodated by the remote modem, V.42 bis or
MNP-5 is used. Otherwise, no data compression is used.

Option
Setting

2 0 2 seconds
3 1 3 seconds
4 2 4 seconds
6 3 6 seconds
12 4 12 seconds
15 5 15 seconds
20 6 20 seconds
30 7 30 seconds
40 8 40 seconds
S7 9 Dial wait is determined by setting S-Register 7. (See “S-Reg-

AT Command
Setting Dial Wait

isters” in Chapter 5 of the 326X Series Modem User’s Guide).

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Commands 1-57

DE

*

AT*DE (DTE Rate)

TERMINAL OPT’S

326X V .32
bis Modem

Auto (1) Auto (1) Auto (1) 22 Modem uses the autobaud feature to determine the

57.6 57.6 57.6 16 The DTE port is configured for 57, 600 bps

38.4 38.4 38.4 15 The DTE port is configured for 38, 400 bps

19.2 (4D) 19.2 (4D) 19.2 12 The DTE port is configured for 19, 200 bps

16.8 16.8 16.8 11 The DTE port is configured for 16, 800 bps

14.4
(2, 3, 4L)

12.0 12.0 12.0 9 The DTE port is configured for 12, 000 bps
9600 9600 9600 8 The DTE port is configured for 9600 bps
7200 7200 7200 7 The DTE port is configured for 7200 bps
4800 4800 4800 6 The DTE port is configured for 4800 bps
2400 2400 2400 5 The DTE port is configured for 2400 bps
1200 1200 1200 4 The DTE port is configured for 1200 bps (2400 bps is

300 300 300 2 The DTE port is configured for 300 bps (2400 bps is

• • •

DTE Rate

Option Setting

326XFAST
Modem

128.0 128.0 28 The DTE port is configured for 128, 000 bps

115.2 115.2 21 The DTE port is configured for 115, 200 bps

96.0 96.0 20 The DTE port is configured for 96, 000 bps

76.8 76.8 19 The DTE port is configured for 76, 800 bps

72.0 72.0 18 The DTE port is configured for 72, 000 bps

64.0 64.0 17 The DTE port is configured for 64, 000 bps

28.8 28.8 26 The DTE port is configured for 28, 800 bps

26.4 26.4 25 The DTE port is configured for 26, 400 bps

24.0
(2, 3, 4L)

21.6 21.6 13 The DTE port is configured for 21, 600 bps

14.4 14.4 10 The DTE port is configured for 14, 400 bps

This option governs the speed at which the modem communicates with the DTE
during data, ACU, and escape modes.

326XFAST­SDC Modem

56.0
(2, 3, 4L)
U.S./Can Only

48.0
(2, 3, 4L)
All Other
Countries

24.0 14 The DTE port is configured for 24, 000 bps

AT Command
Setting Description

rate at which to operate. For a detailed description of
the autobaud feature, see “Autobaud Feature” in
Chapter 5 of the 326X Series Modem User’s Guide.
NOTE: The Autobaud feature is not supported in
synchronous operating modes. When configured for
synchronous operation, if you select Auto, the DTE
will be driven at the previous DTE rate selected
(the factory default is 9600 bps).

24 The DTE port is configured for 56, 000 bps

23 The DTE port is configured for 48, 000 bps

the lowest speed available with the 326XFAST-SDC
Modem)

the lowest speed available with the 326XFAST-SDC
Modem)

1-58 AT Commands

AT*DF (Data Format)

This option allows you to specify the data encoding format to be used during SDC

EC/DC OPT’S

• • •

Data Form

connections. NOTE: This option applies only to SDC data mode. It does not apply to
synchronous ACU’s (V.25 bis or LPDA2) while disconnected. In the online mode,
LPDA2 commands must follow the format of this option.

DF, *DI

*

Option
Setting

NRZ
(all)

NRZI 1 The modem uses the NRZI data encoding format.

AT Command
Setting Description

0 The modem uses the NRZ data encoding format.

AT*DI (Leased to Dial Option)

In an automatic restoral application, the originating modem uses the setting of its

RESTORAL OPT’S

• • •

L to D

DI (L to D, Leased to Dial) command setting as a trigger for automatic restoral.

AT

*

The L to D option selects a threshold for the number of retrains that occurs over a
period of time. The originating modem initiates restoral if the number of retrains that
occur over the designated time exceeds the threshold set by the L to D option.

The default setting for the L to D option is Low/Fast (AT
sensitive setting for this option and allo ws the modem to initiate restoral when signal
quality deteriorates slightly. Leave this option set to Low/Fast to determine if it is
sensitive enough for your application.

If you find that the Low/Fast setting is not sufficiently sensitive, set the AT
(Retrain) command to Low BER to make the modem more sensitive to poor signal
quality. If you find that the modem is too sensitive to poor signal quality, set the
Retrain option to High BER and change the setting of the L to D option to a less
sensitive setting.

DI0). This is the most

*

*

RT

Table 1-5 lists the number of retrains that must occur over a specified time for each
setting of the AT

Table 1-5.
L to D Option Settings

Option
Setting

Low/Fast
(all)

Low/Slow 1 Medium 6 10 12 10
High/Fast 2 Medium 5 5 10 5
High/Slow 3 Low 10 10 20 10

DI command.

*

C.Fast/V.32 bis/V.32
Modulation Modes

AT
Command
Setting Setting

0 High 3 5 6 5

# of
Retrains

Time in
Minutes

All Other
Modulation Modes

# of
Retrains

AT Commands 1-59

Time in
Minutes

DL, *DP

*

AT*DL (RTS/CTS Delay)

The A T*DL (RTS/CTS Delay) command sets the interval for the delay time

TERMINAL OPT’S

RTS/CTS Delay

• • •

between RTS and CTS. These settings only apply when operating in the
asynchronous Direct or synchronous data modes.

Option
Setting

0
(all)

15 1 There is a 15-ms minimum delay before the

60 2 There is a 60-ms minimum delay before the

90 3 There is a 90-ms minimum delay before the

S26 4 RTS/CTS delay is determined by the value of

AT Command
Setting Description

0 There is no RTS/CTS delay.

modem sends the CTS signal to the DTE after
receiving RTS from the DTE.

modem sends the CTS signal to the DTE after
receiving RTS from the DTE.

modem sends the CTS signal to the DTE after
receiving RTS from the DTE.

S-Register 26.

AT*DP (Pause Delay)

The A T*DP (Pause Delay) command forces the modem to pause when the modifiers

DIALING OPT’S

Pause Delay

• • •

are encountered in a dial string or on the command line. The modifiers are as
follows:

•<

•k

•K

Option
Setting

3 0 Pause delay is 3 seconds.
6 1 Pause delay is 6 seconds.
9 2 Pause delay is 9 seconds.
12 3 Pause delay is 12 seconds.
S8 4 Pause delay is determined by S-Register 8.

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

(See “S-Registers” in Chapter 5 of the 326X
Series Modem User’s Guide).

1-60 AT Commands

AT*DR (Auto Redial)

DR, *DS, DS, *DT

*

Data 9600 T/D?

• • •

Auto Redial

The A T*DR (Auto Redial) command determines how many times the modem
redials a failed call. The modem waits for a country-specific time between redials
and displays:

Redial Wait

If you enable the AT*LN (Link Phone #) command, the modem dials all of the
linked numbers before redialing.

AT Command

Option Setting

Off
(all)

1 – 15 1 – 15 The modem redials an unsuccessful call “n” times.

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

Setting Description

0 The modem does not redial an unsuccessful call.

AT*DS, ATDS (Dial a Stored Telephone Number)

See the ATDS command description.

AT*DT (DTR Delay)

The A T*DT (DTR Delay) command determines the amount of time that the modem

TERMINAL OPT’S

DTR

waits after connecting to the dial line before examining the DTR signal from the

• • •

DTE. If the DTR signal is low , the modem disconnects. This feature is used when the
AT Form option is set to SyncData or the V25 Form option is set to AsynSync.
The delay time period allows you to switch an asynchronous terminal to a
synchronous terminal.

Option Setting

S25
(all)

10 sec 1 The modem waits 10 seconds before examining

15 sec 2 The modem waits 15 seconds before examining

AT Command
Setting Description

0 The modem waits the amount of time specified by

S-Register 25 before examining DTR.

DTR.

DTR.

AT Commands 1-61

EC

*

AT*EC (Error Correction)

The A T*EC (EC) command determines which error-correction protocol is used.

EC/DC OPT’S

• • •

EC

NOTE: This option does not apply when the 326XFAST-SDC Modem is configured
for synchronous data compression operation. If both the local and remote
326XFAST-SDC Modems are configured for SDC operation, LAPM error correction
with V.42 bis data compression only is used; no other setting is available

.

Option
Setting

V.42
(all)

LAPM 1 The modems attempt to negotiate LAPM error

MNP 2 The modems attempt to negotiate MNP error

AT Command
Setting Description

0 The modems negotiate the use of LAPM or MNP

error correction. First, the two modems attempt
to negotiate using LAPM. If unsuccessful, they
attempt to negotiate using MNP.

If still unsuccessful, and the Mode option is set to
Auto Reliable or Speed-Dependent Auto
Reliable, the modems use normal mode. If the
Mode option is set to Reliable, the modems
disconnect.

correction.
In asynchronous applications, if a connection is

unsuccessful and the Mode option is set to
Reliable, the local modem disconnects. If the
Mode option is set to Auto Reliable, the modems
use Normal mode. If the Mode option is set to
Speed-Dependent Auto Reliable, and a
connection is established at 1200 bps or less,
Normal mode is used.

correction.
If unsuccessful and the Mode option is set to

Auto Rel, the modems use normal mode. If the
Mode option is set to Rel, the modems
disconnect.

1-62 AT Commands

AT*FC (Fast Call)

The A T*FC (Fast Call) command reduces the time for selected phases of the

MODULATION OPT’S

connect sequence.

• • •

FC

*

Fast Call

Option
Setting

Off
(all)

Lvl1 1 The 2.15 secured billing delay in the answer modem

Lvl2 2 Lvl2 applies to V.32 (coded or uncoded)/V.32 bis/

Lvl3
(2, 3, 4L)

1

Default with the 326XFAST-SDC Modem

1

AT Command
Setting Description

0 This option disables the Fast Call feature.

is eliminated in all modulation modes except Bell
212, V.21, and Bell 103. The length of time ABT is
sent is reduced by 1 second in all modulation modes.

326XFAST modulation modes only. It includes the
Lvl1 functionality and shortens the training time in
the answer and originate modems by approximately 2
seconds.

3 Lvl3 includes the Lvl1 and Lvl2 functionality and

eliminates error-correction negotiation, saving
approximately an additional one half of a second.
For proper operation, be sure to enable this option and
ensure that the AT*SM (Mode), AT*EC (Error
Correction), and the AT*DC (Data Compression)
options (EC/DC OPT'S category) are set the same in
both the answer and originate modems.

If your local and remote 326XFAST -SDC Modems are
configured for synchronous data compression
operation, by selecting Fast Call Lvl3, the modems
use LAPM error correction with V.42 bis data
compression only. For proper operation, be sure to
enable this option in both the local and remote
modems, and ensure that the AT*SM (Mode) is set
the same in both the answer and originate modems.

AT Commands 1-63

FL

*

AT*FL (Flow Control)

The A T*FL (Flow) command allows the modems and DTEs in a link to control the

TERMINAL OPT’S

• • •

Flow

flow of data when buffers near their capacity. Use some type of flow control when
operating in the Normal or Reliable mode. Check the DTE's manual to ensure that
the DTE supports the type of flow control you select.

Option
Setting

Off 0 Flow control is disabled.
XON/XOFF

(all)

DTR/CTS 2 In asynchronous applications, the local modem and

AT Command
Setting Description

1 The local modem and DTE operate flow control by

passing characters embedded in the data stream
between them. The XOFF character signals the
transmitting device to stop sending data. The XON
character allows the halted device to start sending data.
NOTE: XON/XOFF flow control is not supported in
the 326XFAST synchronous data compression mode. If
synchronous data compression is enabled, and you
select XON/XOFF, the modem behaves as if flow
control were disabled.

DTE use DTR/CTS signals to operate flow control. The
terminal uses DTR and the modem uses CTS to signal
when the buffers are full. An on-to-off transition
signals the transmitting device to stop sending data; an
off-to-on transition signals that data can flow. This
setting overrides the CTS option setting when the
modem is in Normal or Reliable mode. If you plan to
use DTR/CTS flow control, set the AT&D (DTR under
the TERMINAL OPT'S menu) command to High.

In applications operating in 326XFAST synchronous
data compression mode, DTR/CTS flow control
functions the same as asynchronous applications with
the following exception: flow control is unidirectional
from the local modem to the DTE through the CTS
signal; the modem uses CTS to signal when the buffers
are full. The DTR signal has no impact on flow control
in synchronous applications.

1-64 AT Commands

*

RTS/CTS 3 In asynchronous applications, the local modem and

DTE use RTS/CTS signals to operate flow control. The
terminal uses RTS to signal when its buffers are full.
The modem uses CTS to signal when its buffers are
full. An on-to-off transition signals the transmitting
device to stop sending data; an off-to-on transition
signals that data can flow. This setting overrides the
AT&R or AT*CT (CTS) command when the modem
is in data mode.

In applications operating in 326XFAST Synchronous
Data Compression mode, RTS/CTS flow control
functions the same as asynchronous applications with
the following exception: flow control is uni-directional
from the local modem to the DTE through the CTS
signal; the modem uses CTS to signal when the buffers
are full. The RTS signal has no impact on flow control
in synchronous applications.

XON/XOFF PT4 XON/XOFF Pass-Through Flow Control. The local

modem and DTE operate flow control by passing
characters embedded in the data stream between them.
The characters are then passed through (PT) to the
remote site to be acted upon. The XOFF character
signals the transmitting device to stop sending data; the
XON character allows the receiving device to start
sending data. Check your DTE's manual to verify if the
DTE recognizes XON/XOFF flow control.

NOTES: (1) Pass-through flow control must be used
with caution when Mode=Normal and Modem
Flow=On because XON/XOFF characters are acted on
by the remote modem at its DCE port. (2) Pass-through
flow control is not applicable in 326XFAST
Synchronous Data Compression mode. If synchronous
data compression is enabled, and you select XON/
XOFF PT, the modem behaves as if flow control were
disabled.

TxClk
(2, 3, 4L)

1

Default with the 326XFAST-SDC Modem

1

5 Transmit Clock. This selection applies only if the

modem is operating in SDC mode. When the Tx Clk
flow control option is selected, the modem uses a
transmit clock for flow control based on available
buffer space. The transmit clock is stopped when the
buffers are full, inhibiting the flow of data from the
DTE. It is started again when buffer space is available.
NOTE: This option is operational only when internal
timing has been selected (Clock=Internal, AT&X).

FL

AT Commands 1-65

HD

*

AT*HD (Hold Dial Line)

The A T*HD (Hold Dialine) command forces the modem to hold a dial restoral

RESTORAL OPT’S

Hold Dialine

• • •

connection while testing a leased line connection. This command applies to modems
configured for restoral.

While operating in dial restoral, the modem periodically returns to the leased line
(according to the time interval specified in the Dial to Leased option), to test the line
in an attempt to reestablish the leased line connection. If, during 21 seconds, the
modem fails to qualify the leased line, data transmission resumes on the held dial
line. If the modem successfully establishes a valid connection on the leased line
(within 21 seconds), it holds the dial restoral connection for the period of time set in
the Hold Dialine option. The modem passes data on the leased line while holding the
dial line.

If a retrain occurs while the modem is testing the leased line, the test is terminated
and the modem returns to the dial line.

After the timer expires, if the leased line is qualified, the dial line is dropped and data
transmission resumes on the leased line.

If the leased line qualification fails (the leased line cannot be qualified after 21
seconds, or if a retrain is initiated), another attempt to qualify the leased line is made
according to the time specified in the Dial to Leased option.

NOTE: When operating with peer -to-peer, or alternate destination restoral, the Hold
Dialine option should be set the same in both modems involved with restoral. In
peer-to-peer restoral, two leased line modems are involved in restoral. In alternate
destination restoral, the remote leased line modem and a local dial modem are
involved in restoral. Figures 1-2(A) and 1-2(B) illustrate examples of peer-to-peer
and alternate destination restoral, respectively.

DTE

Figure 1-2(A). 326X, Peer-to-Peer Restoral

3261 3261

Device A Device B

PSTN

1-66 AT Commands

*

HD

DTE

3260

Device C

3261 3261

Device A Device B

PSTN

Figure 1-2(B). 326X, Alternate Destination Restoral

Option
Setting

Off (all) 0 The Hold Dialine option is disabled; a dial

1 min 1 A dial modem configured for restoral holds the

2 min 2 A dial modem configured for restoral holds the

3 min 3 A dial modem configured for restoral holds the

4 min 4 A dial modem configured for restoral holds the

5 min

1

(4L)

1 Default with the 326XFAST-SDC Modem

AT Command
Setting Description

modem configured for restoral disconnects from
the dial line normally. A leased line modem
configured for restoral disconnects from the dial
line as soon as it connects to the leased line.

dial line for 1 minute. A leased line modem
configured for restoral holds the dial line for 1
minute while testing the leased line.

dial line for 2 minutes. A leased line modem
configured for restoral holds the dial line for 2
minutes while testing the leased line.

dial line for 3 minutes. A leased line modem
configured for restoral holds the dial line for 3
minutes while testing the leased line.

dial line for 4 minutes. A leased line modem
configured for restoral holds the dial line for 4
minutes while testing the leased line.

5 A dial modem configured for restoral holds the

dial line for 5 minutes. A leased line modem
configured for restoral holds the dial line for 5
minutes while testing the leased line.

AT Commands 1-67

LA, *LC

*

AT*LA (DTE Circuit 141)

The A T*LA (DTE Ct 141) command controls whether or not the local DTE can

TERMINAL OPT’S

DTE Ct 141

• • •

send the modem into a local analog loopback by sending a signal on V.24 Circuit 141
(Pin 18) to the modem. The DTE must support Circuit 141 in order to use this option.
NOTE: A local analog loopback test initiated via DTE Circuit 141 is overridden by
front panel or AT test commands.

Option
Setting

Off
(all)

On 1 An off-to-on transition on Circuit 141 (Pin 18)

AT Command
Setting Description

0 The modem does not respond to a signal on

AT*LC (Line Compensation)

The A T*LC (Line Compensation) command enables the modem to compensate for

TELCO OPT’S

Line Compen

• • •

the effects of low loss in the End Office-to-End Office connections. This may occur
when you are making a local call and using round trip delays less than 10 ms. Line
compensation corrects the effects of low loss in the inter-CO connections on the
received signal on short connections. NOTE: The AT
when the modem is set for V.32/V.32 bis operating mode.

Option
Setting

Off
(all)

On 1 Enables the Line Compensation option.

AT Command
Setting Description

0 Disables the Line Compensation option.

Circuit 141 (Pin 18).

causes the modem to initiate a local analog
loopback test.

An on-to-off transition on V.24 Circuit 141
(Pin 18) takes the modem out of a local analog
loopback test.

LC command applies only

*

1-68 AT Commands

AT*LD (DTE Circuit 140)

The A T*LD (DTE Ct 140) command controls whether or not the local DTE can put

TERMINAL OPT’S

DTE Ct 140

• • •

the modem into a remote digital loopback by sending a signal on V.24 Circuit 140
(Pin 21) to the modem. The DTE must support V.24 Circuit 140 to use this option.
NOTE: A remote digital loopback test initiated via DTE Circuit 140 will be
overridden by front panel or AT test commands.

LD, *LE

*

Option
Setting

Off
(all)

On 1 An off-to-on transition on V.24 Circuit 140

AT Command
Setting Description

0 The modem does not respond to a signal on V.24

Circuit 140 (Pin 21).

(Pin 21) sends the modem into a remote digital
loopback test. An on-to-off transition on V.24
Circuit 140 (Pin 21) takes the modem out of a
remote digital loopback test.

AT*LE (Dial to Leased Option, Automatic Disconnect)

The A T*LE (D to L) command allows the modem to automatically disconnect from

RESTORAL OPT’S

• • •

D to L

the dial line and return to the leased line after a specified period.

Option
Setting

Manual
(1, 2, 3)

15 min 1 The modem returns to the leased line after 15

30 min 2 The modem returns to the leased line after 30

1 hour
(4)

2 hours 4 The modem returns to the leased line after 2

4 hours 5 The modem returns to the leased line after 4

AT Command
Setting Description

0 Pressing the Talk/Data key (at the Home

position) returns the modem to the leased line.

minutes.

minutes.

3 The modem returns to the leased line after 1

hour.

hours.

hours.

If you set this option to Manual, an alternate method of disconnection must be used.
For all other settings, the modem automatically disconnects and returns to the leased
line after the selected time expires. Set both modems to the same setting for the D to
L option. NOTE: If Hold Dialine is set to anything b ut Of f, the modem holds the dial
line for the specified time period.

AT Commands 1-69

LL, *LN

*

AT*LL (Local Analog Loopback Test Busy Out)

The A T*LL (LAL Busy Out) command determines whether the modem appears

TEST OPT’S

LAL Busy Out

• • •

AT*LN (Link Telephone Numbers)

busy to incoming calls during a local analog loopback test. NOTE: Set the AT&J
(TELCO OPT'S Telco option) to RJ4MB before enabling this option.

Option
Setting

Off
(all)

On 1 The modem connects to the line during a local

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT Command
Setting Description

0 The modem does not busy out the line during a

local analog loopback test, allowing incoming
calls to ring.

analog loopback test, making the line appear
busy to incoming calls.

Data 9600 T/D?

Link Phone #

The A T*LN (Link Phone #) command allows you to link telephone numbers that

• • •

are stored in the modem's telephone book. Some remote applications provide more
than one telephone number to call; if one is busy, you can call another. If a call
attempt to a specified number fails and that number has been linked to another, the
modem momentarily displays:

Link Wait

and then calls the second (linked) number. NOTE: If you enable the AT*LN (Link
Phone #), the modem dials linked numbers before redialing (see the AT
in this chapter).

The AT

You can also line telephone numbers using the AT
AT
from (n), a comma, and the number which you want to link (m). A typical AT
command entry would look like the following:

In this example, memory location 2 is linked to memory location 4. To clear the link
between memory locations 2 and 4, enter AT
is now linked to no memory location.

LNn,m Command

*

LN command, followed by the memory location of the number you want to link

*

AT*LN2,4

*

LN command. Enter the

*

LN2. Effectively, memory location 2

DR section

*

*

LN

1-70 AT Commands

LN, *LS

*

The Front Panel

See the "Performing Numeric Entry" section in Chapter 2 of this guide for details on
how to use numeric entry.

1) Step across the Status/Option Sets/Dialing menu by pressing until you see:

Link Phone#=1

2) Press until the display shows the address number you want to link.

3) Press . The display shows the address that the selected address is currently
linked to. For example:

Link #1 to None

In this example, the phone number in address 1 is not linked to another
number.

4) Press until the desired address appears and press . For example, when
address 1 is linked to address 2, the display shows:

Link #1 to #2

In this example, if you initiated a call for the number stored in address 1 and
the call fails, the modem then calls the number stored in address 2.

AT*LS (Low Speed)

The A T*LS (Low Speed) command determines which low-speed modulation mode

MODULATION OPT’S

Low Speed

is used in the event that a higher (C.Fast, V.32 bis, V.32, or V.22 bis) modulation

• • •

mode connection cannot be made when the modem is set to Mod=C.Fast Auto,
V32bis Auto or Auto V32.

Option
Setting

Bell 0 Bell 103 modulation mode is used.
CCITT 1 V.21 modulation mode is used.

AT Command
Setting Description

AT Commands 1-71

LT, *MD

*

AT*LT (DTE Pin 25)

The A T*LT (DTE Pin 25) command controls whether the modem uses EIA/TIA

TERMINAL OPT’S

Dte Pin 25

• • •

232-D Pin 25 as an input or an output. Set rear panel Switch 2 to match the setting of
this option (see Table 2-2 in Chapter 2 of the 326X Series Modem User’s Guide for
more information on rear panel switches).

Option
Setting

Busy 0 The DTE signals the modem on Pin 25 to make the modem

Test
(all)

AT Command
Setting Description

1 The modem signals the DTE on V.24 Circuit 142

NOTE: These settings are country-specific. Consult Appendix C, Country-Specific
Information, in the 326X Series Modem User’s Guide for the settings that are valid in
your country.

AT*MD (PSTN Signaling)

The A T*MD (public switched telephone network [PSTN]) command determines

MODULATION OPT’S

PSTN

how your modem handles disconnect signaling when operating in the C.Fast, V.32

• • •

bis or V.32 modulation mode.

Option
Setting

Off 0 Your modem disconnects without signaling the remote

On
(all)

AT Command
Setting Description

1 Your modem signals the remote modem to disconnect by

appear busy to incoming calls. Set rear panel DIP switch 2
to the off (up) position. Also, for this feature to work, the
AT&J (Telco option) command must be set to RJ4MB.

(Pin 25) when a test is in progress.

modem.

sending PSTN cleardown.

1-72 AT Commands

MD

*

The following two matrixes summarize how the settings for the AT*MD (PSTN)
and the ATY (Longspace) commands interact to affect the behavior of your modem.

• For C.Fast, V.32, and V.32 and V.32 Uncoded Modulation Modes

AT*MD (PSTN)

On Off

ATY (Longspace)

On The modem signals the remote

modem to disconnect (PSTN),
and disconnects when it receives
space that exceeds 1.6 seconds in
durations modem responds to the

MD (PSTN) signal from the

AT

*

remote modem.

Off The modem signals the remote

modem to disconnect (PSTN).
The modem does not disconnect
when it receives space that
exceeds 1.6 seconds in duration.
The modem does respond to the
AT*MD (PSTN) signal from the
remote modem.

The modem disconnects when it
receives space that exceeds 1.6
seconds in duration. When
terminating a call, the modem
sends continuous space for 4
seconds. The modem does
respond to the AT*MD (PSTN)
signal from the remote modem.

The modem disconnects without
signaling the remote modem, and
without sending continuous space
for 4 seconds. The modem does
not disconnect when it receives
space that exceeds 1.6 seconds in
duration. The modem does
respond to the AT*MD (PSTN)
signal from the remote modem.

• For V.22 bis, V.21, Bell 212 and Bell 103 Modulation Modes

AT*MD (PSTN)

On Off

ATY (Longspace)

On The modem disconnects when it

receives space that exceeds 1.6
seconds in duration. When
terminating a call, the modem
sends continuous space for 4
seconds.

Off The modem disconnects without

signaling the remote modem, and
without sending continuous space
for 4 seconds. The modem does
not disconnect when it receives
space that exceeds 1.6 seconds in
duration.

The modem disconnects when it
receives space that exceeds 1.6
seconds in duration. When
terminating a call, the modem
sends continuous space for 4
seconds.

The modem disconnects without
signaling the remote modem, and
without sending continuous space
for 4 seconds. The modem does
not disconnect when it receives
space that exceeds 1.6 seconds in
duration.

AT Commands 1-73

MF, *MM

*

AT*MF (Modem Flow Control)

The A T*MF (Modem Flow) command allows the modem to generate and respond

EC/DC OPT’S

Modem Flow

• • •

AT*MM (Modulation Mode)

to XON/XOFF flow control signals received at the DIAL LINE or LEASED LINE
port. NOTE: This option only applies to the Normal data transfer mode.

Option
Setting

Off 0 The modem flow control is not used.
On

(all)

AT Command
Setting Description

1 The modem periodically sends XON signals to

the remote modem when it is able to receive data.
When the modem becomes unable to receive
data, it sends an XOFF signal to the remote
modem. Likewise, the modem acts according to
XON/XOFF signals received from the remote
modem by starting or stopping the transmission
of data.

MODULATION OPT’S

Mod

The A T*MM (Mod) command determines the modulation mode used by the modem
in data transmission. Changing modulation mode resets the AT

• • •

MN (Min Rate) commands to their defaults for the modulation mode selected.

AT

*

Option
Setting

C.Fast Auto

1

(all)

C.Fast Only 11 The modem negotiates the highest common

AT Command
Setting Description

10 The modem negotiates the highest common

connection in one of the following modulation
modes:

C.Fast
V.32 bis
V.32
V.22 bis
Bell 212

V.21 or Bell 103 (depending on the setting of the
Low Speed option). NOTE: This selection does
not appear if you have the 326X V.32 bis Series
Modem.

connection in the Motorola proprietary
modulation mode C.Fast. NOTE: This selection
does not appear if you have the 326X V.32 bis
Series Modem.

MX (Max Rate) and

*

1-74 AT Commands

*

MM

Option
Setting

V32bis Auto

2

(all)

Auto V32 1 The modem negotiates the highest common

V32bis only 2 V.32 bis or V.32 modulation mode is used.
V32 only 3 V.32 modulation mode is used.
V32 Uncoded 12 The V.32 modulation scheme is used without the

V22bis only 4 V.22 bis modulation mode is used.
212 only 5 Bell 212 modulation mode is used.
103 only 6 Bell 103 modulation mode is used.
V21 only 7 V.21 modulation mode is used.

1

Default in 326XFAST/326XFAST-SDC Product

2

Default in V.32 bis Product

AT Command
Setting Description

0 The modem negotiates the highest common

connection in one of the following modulation
modes:

V.32 bis
V.32
V.22 bis
Bell 212

V.21 or Bell 103 (depending on the setting of the
Low Speed option).

connection in one of the following modulation
modes:

V.32
V.22 bis
Bell 212

V.21 or Bell 103 (depending on the setting of the
Low Speed option)

Trellis-coded Modulation (TCM) scheme. This
selection reduces end-to-end data delay. W ith this
selection you do not have an embedded
secondary channel (i.e. network management
and remote configuration are not available).

AT Commands 1-75

MN, *MR, &S, *MS

*

AT*MN (Minimum Rate)

The A T*MN (Min Rate) command sets the minimum rate at which the modems

MODULATION OPT’S

Min Rate

communicate. Settings vary depending on the modulation mode you choose, but

• • •

some of the following speeds are available.

Option Setting

326X V .32
bis Modem

300
(all)

1200 1200 1200 1 1200
2400 2400 2400 2 2400
4800 4800 4800 3 4800
7200 7200 7200 4 7200
9600 9600 9600

12.0 12.0 12.0 6 12,000

14.4 14.4 14.4 7 14,400

AT
326XFAST
Modem

300
(all)

16.8 16.8 8 16,800

19.2 19.2 9 19,200

21.6 21.6 10 21,600

24.0 24.0 11 24,000

326XFAST­SDC Modem

300
(1)

(2, 3, 4L)

Command

Setting

0 300

5 9600

Minimum Modem
Modulation Rate (bps)

NOTE: When the C.Fast Auto modulation mode is selected, the 326X Series
Modem negotiates data rates from 300 to 24,000 bps. When the C.Fast Only
modulation mode is selected, the modem negotiates data rates from 9600 to
24,000 bps.

AT*MR, AT&S (DSR Control)

See the AT&S command description.

AT*MS (AT Messages)

The A T*MS (AT Msg) command determines when the AT connect message is sent

ACU OPT’S

• • •

AT Msg

to the DTE.

AT Command

Option Setting

Before CD
(all)

After CD 0 The AT connect message is sent to the DTE after

Setting Description

1 The AT connect message is sent to the DTE before

DCD is raised.

DCD is raised.

1-76 AT Commands

AT*MX (Maximum Rate)

The A T*MX (Max Rate) command sets the maximum rate at which the modems

MODULATION OPT’S

Max Rate

communicate over the analog network. Settings will vary depending on the

• • •

modulation mode you choose, but some of the following speeds will be available.

Option Setting

326X V .32
bis Modem

14.4
(all)

12.0 12.0 12.0 6 12,000
9600 9600 9600 5 9600
7200 7200 7200 4 7200
4800 4800 4800 3 4800
2400 2400 2400 2 2400
1200 1200 1200 1 1200
300 300 300 0 300

AT
326XFAST
Modem

24.0
(all)

21.6 21.6

19.2 19.2

16.8 16.8

14.4 14.4 7 14,400

326XFAST­SDC Modem

24.0
(all)

3
3
3

Command

Setting

11 24,000

10 21,600

9 19,200

8 16,800

Maximum Modem
Modulation Rates (bps)

MX, *NB

*

NOTE: When the C.Fast Auto modulation mode is selected, the 326X Series
Modem negotiates data rates from 300 to 24,000 bps. When the C.Fast Only
modulation mode is selected, the modem negotiates data rates from 9600 to 24,000
bps.

AT*NB (Buffer Option)

The A T*NB (Buffer Option) allows you to specify whether normal or reduced sized

EC/DC OPT’S

• • •

Buffers

buffers are used to store data received from a local DTE. Use this option if you have
DTE-to-DTE flow control enabled to reduce the amount of data sent to the remote
DTE when a flow-off condition is received at the local DTE.

NOTE: This option is available only when Mode= Normal (AT

Option Setting

Regular
(all)

Reduced 1 Reduced sized buffers are used allowing less data

SM).

*

AT Command
Setting Description

0 Normal capacity buffers are used.

to be accumulated in the modem.

AT Commands 1-77

NC, *ND

*

AT*NC (Network Compensation)

The Network Compensation option allows you to enhance the performance

TELCO OPT’S

Network Comp

• • •

reliability of the 326XFAST/326XFAST-SDC Modem when operating with certain
types of network equipment.

NOTES:

1) This option is available only when the C.Fast Auto or C.Fast Only modulation
modes are selected.

2) This option applies to Releases 5.2 and greater of the 326XFAST/326XFAST-
SDC Modems only.

AT Command

Option Setting

Off
(default)

Lvl1 1 Select Lvl1 if the modem is experiencing

Lvl2 2 Lvl2 is recommended when performance

Setting Description

0 Off should be selected when making most normal

connections within a continent.

performance problems when connected to a line
terminating equipment via a short loop, having
low loop loss with below normal receive signal
levels (for example, when operating behind a low
grade PBX). NOTE: This selection limits the
maximum possible DCE data rate to 21,600 bps.

problems are encountered making
intercontinental calls. NOTE: This selection
limits the maximum possible DCE data rate to
19,200 bps.

When operating in an environment where the
conditions described for Lvl1 and Lvl2 exist,
Lvl2 is recommended to enhance performance.

AT*ND (View Stored Telephone Numbers)

DATA 9600 T/D?

View Phone #

1-78 AT Commands

• • •

The A T*ND (Vie w Phone #) command displays the telephone numbers stored in the
modem's nine telephone book addresses.

The AT

To view the telephone numbers stored in your modem's memory, enter:

The Front Panel

Select the address you want displayed at View Phone #. See the "Performing
Numeric Entry" section in Chapter 2 for details on how to use numeric entry.

ND Command

*

AT*ND<CR>

AT*OC (External Control)

The A T*OC (Ext Cntrl) command chooses which pin the AT*OP (Ext Select)

TERMINAL OPT’S

• • •

Ext Cntrl

command responds to. NOTE: If the A T

AT Command

Option Setting

Pin 14
(all)

Pin 20 1 The Ext Select option loads an option set based upon

Setting Description

0 The Ext Select option loads an option set based upon

AT*OP (External Option Set Select)

OC, *OP

*

OP is set to 0, this command has no effect.

*

the transition of Pin 14. This setting overrides the
AT*RE (Restore) command setting FP/116 or FP/

116.ACU.

the transition of Pin 20. When using this setting, set
the AT&D (DTR) command to High. This setting
overrides the AT
FP/108.1 and FP/108.ACU and all AT&D (DTR)
command settings except High.

RE (Restore) command settings

*

TERMINAL OPT’S

Ext Select

The A T*OP (Ext Select, also known as 116 Select) command controls how the
modem uses an external pin to select option sets. The pin used is defined by the

• • •

OC (Ext Cntrl) command. NOTE: Upon power up, if the modem is configured

AT

*

for Power Up In=Old, it reads the AT
set accordingly.

AT Command

Option Setting

Off
(all)

nH-mL 1-12, where:

Setting Description

0 The A T*OP (Ext Select) command is disabled.

1 = 1H/2L
2 = 1H/3L
3 = 1H/4L
4 = 2H/1L
5 = 2H/3L
6 = 2H/4L
7 = 3H/1L
8 = 3H/2L
9 = 3H/4L
10 = 4H/1L
11 = 4H/2L
12 = 4H/3L

OC (Ext Control) option and sets the option

*

There are 12 settings with the format nH-mL, where
n = 1, 2, 3, or 4, and m = 1, 2, 3, or 4. When the pin
specified by the Ext Cntrl option (Pin 14 or Pin 20)
transitions from low to high, the modem loads the
“H” option set. When the pin specified by the Ext
Cntrl option (Pin 14 or Pin 20) transitions from high
to low, the modem loads the “L” option set.

For example, if you set Ext Select=1H/2L and the
pin specified by the Ext Cntrl option (Pin 14 or Pin

20) transitions from low to high, the modem loads
Option Set 1. If the pin specified by the Ext Cntrl
option (Pin 14 or Pin 20) transitions from high to
low, the modem loads Option Set 2.

When an option set is loaded due to the pin specified
by the Ext Cntrl option (Pin 14 or Pin 20) transition,
the modem disconnects from the line.

AT Commands 1-79

OS, *PE, *PF

*

AT*OS (Overspeed)

The A T*OS (Overspeed) command allows the modem to compensate for DTE

TERMINAL OPT’S

• • •

Overspeed

AT*PE (Enable/Disable Password Protection)

FP SECURITY

• • •

Password

overspeed. Some asynchronous DTEs send data to the modem faster than specified, a
condition known as overspeed.

Option
Setting

1.0%
(all)

2.5% 1 The modem compensates for DTE overspeed up to 2.5%.

The A T*PE (Password) command enables and disables the Password function. Once
you have enabled the Password function, set protection in order to lock the modem
(see A T

Option Setting

Enable 1 AT*PE1 enables password.
Disable 0 AT*PE0 disables password.

AT Command
Setting Description

0 The modem compensates for DTE overspeed up to 1.0%.

PF).

*

AT Command
Setting Description

When you set protection, you must use a password before you can access the
protected functions. Otherwise, you do not need to enter a password to access any
modem function. Refer to the AT
changing a password.

AT*PF (Set Protection)

The A T*PF (Set Protection) command allows you to set protection in order to lock

FP SECURITY

Password

• • •

Set Protection?

the modem. Refer to the AT

Option Setting

Set Protection? AT*PF Use the AT*PF command to lock your modem.

The Front Panel

After you have enabled the password function explained in the AT
description, you must set protection.

To set protection:

1) Display:

Set Protection?

2) Press . The modem responds with: Password Protected

PW command for details on creating and

*

PN command for details on entering a password.

*

AT Command
Setting Description

PE command

*

1-80 AT Commands

The modem is now locked and it is necessary to enter your password to access
locked functions. If you try to access locked functions, the modem responds with:

Password Locked

AT*PN (Unlock Password Protection)

To unlock a password protected modem and gain access to all modem functions, use

FP SECURITY

Enter Password

• • •

the A T
with the command.

You can also use the front panel option to gain access to all modem functions. Do the
following:

Your modem relocks the password protected features after five minutes of no
activity. To lock the modem before the default time expires, see the AT
command.

PNxxxx command. xxxx represents the password, which must be entered

*

1) Display:

Enter Password?

2) Press . The modem displays:

Enter PW:0000

3) The cursor on the leftmost zero is flashing, indicating it is selected. Using
to select digits 0 – 9, and to move the cursor to the right, enter your new
password. If you should incorrectly enter the password, press and the
modem displays:

Entry Cancelled!

4) Once you have entered the password correctly, press . The modem displays:

Passwd Unlocked

5) If you should enter an incorrect password, the modem responds with:

Invalid Password

PN, *PT

*

PF

*

AT*PT (Dial Type)

See the ATP command description described earlier.

AT Commands 1-81

PW, *RA

*

AT*PW (Change Password)

The A T*PW (Change Password) command is used as follows:

FP SECURITY

Change Password

• • •

AT*PWold password/new password<CR>

If the change is successful, the modem responds with:

OK

The Front Panel

1) Display:

Change Password

2) Press . The modem responds with:

Old PW:0000

3) The cursor on the leftmost zero is flashing, indicating it is selected. Using
to select digits 0 – 9, and to move the cursor to the right, enter your old
password. If you are entering a password for the first time, enter the factory
default password of four zeros (0000). Press again. The modem responds
with:

New PW:0000

4) The cursor on the leftmost zero is flashing, indicating it is selected. Using
to select digits 0 – 9, and to move the cursor to the right, enter your new
password. Your password must contain four characters; the characters are
limited to 0 – 9. Press . The modem responds with:

Verify PW:xxxx

where “xxxx” is the password you have just entered.

5) If the password displayed is correct, press again. The modem responds
with:

Password Saved!

6) If the password is incorrect, press any front panel key other than to abort
the Change Password function.

AT*RA (Remote Access)

The A T*RA (RmtAcc) command determines whether your modem allows itself to

RMT CONFIG OPT’S

RmtAcc

be configured by the remote modem.

• • •

Option Setting

Enable
(all)

Disable 0 The local modem cannot be configured by the

AT Command
Setting Description

1 The local modem can be configured by the remote

modem.

remote modem.

1-82 AT Commands

AT*RC (Initiate, Terminate, or Abort Remote Configuration
Session)

The A T*RC command allows you to initiate, terminate, or abort a remote

RMT CONFIG OPT’S

configuration session with the connected modem.

• • •

RC

*

Init Rmt Cnfg?

AT Command

Option Setting

Initiate Rmt
Cnfg?

Terminate 0 The modem terminates a remote configuration

Abort 1 The modem aborts a remote configuration session

Setting Description

2 The modem attempts to initiate a remote

configuration session with the connected modem.

session with the connected modem. Changes to the
remote modem's configuration are saved. This
setting is not displayed unless you are already in a
remote configuration session.

with the connected modem. Changes made to the
remote modem's configuration are not saved. This
setting is not displayed unless you are already in a
remote configuration session.

Initiating a Remote Configuration Session with a Dial
Modem

The AT*RC Command

To use the AT
modem:

RC command to initiate a remote configuration session with a dial

*

1) Establish a dial-line connection with the remote modem at 7200 bps or greater.

2) Enter:

AT*RC2<CR>

3) Your terminal displays:

INITIATING RC

When the remote configuration session has been established, your terminal
displays:

RC ESTABLISHED

If unsuccessful, the terminal displays:

RC FAILED!

or

RC DENIED!

AT Commands 1-83

*

RC

The Front Panel

To initiate a remote configuration session with a dial modem, use your front panel to:

1) Establish a dial-line connection with the remote modem at 7200 bps or greater.

2) Press to move to the “home” position on the front panel menu tree.

3) Press until the RMT CONFIG OPT'S menu appears.

4) Press to display:

Init Rmt Cnfg?

5) Press . The modem displays:

Initiating RC...

If successful, the modem displays:

RC Established!

If unsuccessful, the modem displays:

RC Failed!

or

RC Denied!

Failure to establish a remote configuration session can be caused by the following:

• The remote modem's AT

• The remote modem is running a test.

• You have already established a remote configuration session with the remote
modem, but via a different means. (For e xample, you hav e already established a
remote configuration session using your AT ACU, and you are now trying to
use your front panel to do the same thing).

RA (Rmt Acc) command is set to Disabled.

*

1-84 AT Commands

*

Initiating a Remote Configuration Session with a Leased
Line Modem

The leased line remote configuration function makes use of the SET RMT LL ADDR
and SRCH RMT LL ADDR menus. Before be ginning a remote configuration session
with a leased line modem, you must know the remote modem's address. If you have
not yet assigned the remote modem an address, or cannot find its address, see the
“SET RMT LL ADDR” menu and “SRCH RMT LL ADDR” menu sections in
Chapter 2 of this guide first.

To initiate a remote configuration session with a leased-line modem:

1) Establish a leased-line connection with the remote modem at 7200 bps or
greater.

2) Press to move to the “Home” position on the front panel menu tree.

3) Press until the RMT CONFIG OPT'S menu appears.

4) Press to display:

Init Rmt Cnfg?

5) Press . The modem displays:

Rmt Address=000

The leftmost 0 is blinking. Enter the remote modem's address. Using , select the
first digit of the leased line modem's address. Press to move the cursor to the next
digit. Use again to select the second digit. Once you have finished entering all
three digits of the remote modem's address, press . The modem displays:

RC

Initiating RC...

If successful, the modem displays:

RC Established

If unsuccessful, the modem displays:

RC Failed!

or

RC Denied!

Failure to establish a remote configuration session can be caused by the following:

• The remote modem's Rmt Acc option is set to Disabled (AT

• The remote modem is running a test.

RA0).

*

AT Commands 1-85

*

RC

Terminating a Remote Configuration Session

When you terminate a remote configuration session, changes made to the remote
modem's configuration are automatically saved.

The AT

To use the AT*RC command to terminate a session:

The remote configuration session is terminated, and the remote modem saves
changes made to it during the session.

The Front Panel

To use your front panel to terminate a session:

RC Command

*

1) Enter:

AT*RC0<CR>

2) Your terminal displays:

RC COMPLETE
OK

3) You are now in escape mode. To return online, enter:

ATO<CR>

1) Display:

Rmt Cnfg=Established

2) Press until the modem displays:

Rmt Cnfg:Terminate

3) Press . The modem displays:

RC Complete!

Aborting a Remote Configuration Session

When you abort a remote configuration session, changes made to the remote
modem's configuration are not saved.

The AT

To use the AT*RC command to abort a session:

The Front Panel

To use your front panel to abort a session:

RC Command

*

1) Enter:

AT*RC1<CR>

2) Your terminal displays:

RC ABORTED
OK

1) Display:

Rmt Cnfg=Established

2) Press until the modem displays:

Rmt Cnfg:Abort

3) Press . The modem displays:

RC Aborted!

1-86 AT Commands

AT*RE (Initiate/Terminate Restoral)

The A T*RE (Restoral) command determines how modems operating on a leased

RESTORAL OPT’S

Restore

line handle initiation of dial restoral. The 326X Series provides four different

• • •

methods of initiating restoral:

• Automatic

• Manual

• DTE signal

• DTE ACU

Option Set 4 configures the modem for automatic restoral initiation (Restore=FP/
Auto). NOTE: The Restoral option and its option settings appear on your modem's
front panel only if you have the Restoral option installed. The 326X Series Modem
models that include the Restoral option are the 3261, 3263, 3266, and 3268.

AT Command

Option Setting

Off
(1, 2, 3, 4D)

FP Only 1 Manual initiation allows you to initiate and terminate

FP/108.1 2 The 326X Series Modem allows the DTE to initiate

Setting Description

0 This option disables the initiation of restoral.

RE

*

restoral by pressing the Talk/Data key ( key in the
Home position) on the modem's front panel.

restoral using its DTR signal. In DTR restoral, an
off-to-on DTR transition from the DTE interface
initiates restoral. This option is provided for DTEs
that cannot manipulate Circuit 116 for restoral
purposes. In DTR restoral, either the answering or
originating modem can initiate restoral when the
connected DTE turns DTR from off to on by dialing
the number stored in its telephone directory, based on
the setting of the Default Dial option.

Once a call is successful, an on-to-off transition of
DTR from the DTE disconnects the modem from the
dial line and returns it to the leased line.

Once restoral is terminated by any means other than
the DTR signal, the DTR signal from the attached
DTE must be turned off before an off-to-on DTR
transition can initiate another restoral attempt.

NOTE: The Ext Select option o v errides DTR restoral
if Ext Cntrl option is configured for Pin 20 and the
Ext Select option is configured for a setting other than
Off.

AT Commands 1-87

*

RE

AT Command

Option Setting

FP/116 3 The 326X Series allows the DTE to initiate restoral

FP/Auto
(4L)

Setting Description

with Circuit 116. Circuit 116 allows you to use off-to­on transitions of this signal from the DTE to initiate
restoral, according to CCITT V.24 specifications.
In Circuit 116 restoral, the answer or originating
modem can initiate restoral (when the connected DTE
turns Circuit 116 from off to on) by dialing the
number stored in its telephone directory, based on the
setting of the Default Dial option. You can initiate
restoral manually by pressing the Talk/Data key
( at the Home position) on the front panel.

Once a call is successful, an on-to-off transition of
Circuit 116 disconnects the affected modem from the
dial line and returns it to the leased line. You can
manually disconnect either modem from the dial line
by pressing the Talk/Data key ( at the Home
position) on the front panel.

4 In automatic restoral, the originating modem on the

leased line determines when restoral takes place. The
answer modem cannot automatically initiate restoral;
it can only answer an inbound call, thus ensuring that
both modems do not try to call each other at the same
time. Such an occurrence would result in a failed
restoral attempt.

During data transmission, the originating modem
monitors leased line signal quality by counting the
number of retrains, both inbound and outbound, that
occur over a specified time period. NOTE: Retrains
that cause a change (through the Adaptive Rate
feature) are not counted.

If the number of retrains over a period of time exceeds
the threshold set by the L to D (Leased to Dial)
option, or if the modem does not receive answers to
its training sequences, the originating modem initiates
restoral by dialing the number stored in its telephone
directory, based on the setting of the Default Dial
option.

Once the modems are using the dial line, the
originating modem continues to count retrains on the
dial line. If the number of retrains over a period of
time exceeds the threshold set by the L to D (Leased
to Dial) option, the originating modem disconnects
from the dial line and returns to the leased line.

1-88 AT Commands

*

AT Command

Option Setting

FP/108.ACU 5 The 108.ACU restoral setting allows you to use

FP/116.ACU 6 The 116.ACU restoral setting allows you to use

Setting Description

off-to-on transitions of this signal from the DTE to
activate the ACU. This allows the modem to accept
dial commands. In the FP/108.ACU restoral setting,
the answer or originating modem can enable the ACU
when the connected DTE turns Circuit 116 from off to
on.

Once a call is successful, an on-to-off transition of
DTR disconnects the affected modem from the dial
line and returns it to the leased line.

If a call is terminated by any means other than DTR,
the modem remains in a disconnected state waiting
for ACU commands. An on-to-off transition is
required to return to the leased line.

NOTE: The Ext Select option o v errides FP/108.ACU
restoral if Ext Cntrl option is configured for Pin 20
and the Ext Select option is configured for a setting
other than Off.

off-to-on transitions of this signal from the DTE to
activate the ACU. This allows the modem to accept
dial commands to initiate restoral. In the 116.ACU
restoral setting, the answer or originating modem can
enable the ACU when the connected DTE turns
Circuit 116 from off to on.

Once a call is successful, an on-to-off transition of
Circuit 116 disconnects the affected modem from the
dial line and returns it to the leased line.

If a call is terminated by any means other than Circuit
116, the modem remains in a disconnected state
waiting for ACU commands. An on-to-off transition
is required to return to the leased line.

NOTE: The Ext Select option o v errides FP/116.ACU
restoral if Ext Cntrl option is configured for Pin 14
and the Ext Select option is configured for a setting
other than Off.

RE

AT Commands 1-89

RP

*

AT*RP (Parity)

ACU OPT’S

• • •

Parity

When using the ASCII character set, you must select the parity used by the modem
and DTE. The Parity option applies to only asynchronous and character-synchronous
data formats. The modem ignores parity bits if you are using a bit-synchronous
protocol, but adds parity bits to all data units in the message field in its responses to
the DTE.

NOTE: This command is allowed only when remotely configuring another modem
via the AT Remote Config command. If this command is issued at any other time, an
ERROR response is returned to the DTE and the setting of the parity strap remains
unchanged.

AT Command

Option Setting

V.25
(all)

Even 1 Parity is even. A one or zero is added to each 7-bit

Odd 2 Parity is odd. A one or zero is added to each 7-bit

Mark 3 Parity is a Mark. A one is added to each 7-bit

Space 4 Parity is a Space. A zero is added to each 7-bit

Setting Description

0 Sets parity according to V.25 bis specifications.

The following parity applies:
Parity is a Space for bit-synchronous protocol.

A zero is added to each 7-bit character in the
message field. Parity is odd for character­synchronous protocol. A one or zero is added to
each 7-bit character making the total number of
one bits equal to an odd number. Parity is even for
asynchronous data format. A one or zero is added
to each 7-bit character making the total number of
one bits equal an even number.

character making the total number of one bits
equal an even number.

character making the total number of one bits
equal an odd number.

character.

character (no parity).

1-90 AT Commands

AT*RS (RTS Control)

The A T*RS (RTS) command determines how the modem interprets the RTS signal.

TERMINAL OPT’S

RTS

The DTE signals the modem with the RTS on EIA/TIA 232-D Pin 4 (V.24 Circuit

• • •

105).

Option Setting

Normal
(2, 3, 4)

High (1) 1 The modem sets RTS high. Use this setting if the

Remote 2 This setting applies to simulated half-duplex

RS

*

AT Command
Setting Description

0 The DTE controls data transmission with RTS.

DTE does not provide RTS. If you are using
Normal or Reliable data transfer mode and you are
using RTS/CTS flow control, this setting is
overridden and RTS behaves as if RTS=Normal

applications and works only if the remote modem
also supports RTS/DCD signaling. For this appli­cation to work properly, the DCD option at the
remote site must be set to Remote. Coordinate
your setting with the remote site.

When the local DTE turns RTS on, it forces DCD
on at the remote modem. The remote modem can
only receive data during this period. Once the local
DTE drops RTS, DCD at the remote modem
follows. The RemRST/DCD option allows you to
choose the type of RTS/DCD signaling.

NOTE: This setting functions as described only
when the modem is in the Direct data transfer
modem, and not using the V.21 or Bell 103
modulation mode. If the modem is using the V.21
or Bell 103 modulation mode, or not using the
Direct data transfer mode, RTS behaves as if
RTS=Normal

AT Commands 1-91

RT

*

AT*RT (Auto Retrain)

The A T*RT (Retrain) command enables the auto-retrain feature. When enabled, the

MODULATION OPT’S

Retrain

modem retrains if the specified bit error rate is exceeded. Enable Retrain for most

• • •

applications because retrains allow the modem to compensate for changing line
conditions. NOTE: When you set this feature to Off, the modem is unable to detect
when the central office has initiated a loopback test on the data communications line.

Option Setting

Off 0 The modem does not automatically initiate

Low BER 1 Using C.Fast, V.32 bis, V.32, or V.32 Uncoded

High BER
(all)

AT Command
Setting Description

retrains, but will respond to retrains from the
remote modem.

the modem retrains when the bit error rate (BER)
exceeds approximately 10-4 for eight seconds.

Using V.22 bis, the modem retrains when the bit
error rate (BER) exceeds approximately 10-4 for
one second.

The Low BER setting is more sensitive than the
High BER setting. When ARS is enabled, this
setting has no meaning.

2 Using C.Fast, V.32 bis, or V.32, the modem

retrains when the bit error rate (BER) exceeds
approximately 10-3 for eight seconds.

Using V.22 bis, the modem retrains when the
bit-error rate (BER) exceeds approximately 10-3
for one second. When ARS is enabled, bit error
rate is always used.

The High BER setting is less sensitive than the
Low BER setting. NOTE: Motorola
recommends this setting for most applications.

1-92 AT Commands

AT*SC (Speed Conversion)

The A T*SC (Speed Conver) command determines whether the modem uses the

TERMINAL OPT’S

Speed Conver

speed conversion feature. NOTE: This option does not apply when the modem is in

• • •

the Direct or synchronous data transfer mode.

AT Command

Option Setting

Off 0 The modem adjusts its DTE port speed to match

On
(all)

Setting Description

1 DTE-to-modem speed remains constant,

AT*SI (DTE Inactivity)

The A T*SI (Inactivity) command allows you to select the length of the time the

TERMINAL OPT’S

Inactivity

modem waits before disconnecting when no data is being transferred. NOTE: This

• • •

option does not apply when the modem is set for the synchronous data transfer
mode.

SC, *SI

*

the speed of the negotiated data link.

regardless of the negotiated data link speed. (The
exception is Direct data mode. In this case,
DTE-to-modem speed must always match the
modem-to-modem speed.)

AT Command

Option Setting

Off
(all)

3min AT*SI1 The modem will disconnect if 3 minutes elapses

10min AT*SI2 The modem will disconnect if 10 minutes elapses

20min AT*SI3 The modem will disconnect if 20 minutes elapses

30min AT*SI4 The modem will disconnect if 30 minutes elapses

S30 AT*SI5 The inactivity timeout is controlled by the value

Setting Description

AT*SI The Off option disables the inactivity timer.

without data transfer to or from the DTE.

without data transfer to or from the DTE.

without data transfer to or from the DTE.

without data transfer to or from the DTE.

set in S-Register 30.

AT Commands 1-93