Multi-Tech Systems V.92, V.34 User Manual

SocketModem™

MT5634SMI V.34 & V.92

AT Commands

Fax Class 1 Commands

Fax Class 2 Commands

Voice Commands

Reference Guide

Copyright and Technical Support

SocketModem Reference Guide

Serial: MT5634SMI-34, MT5634SMI-92
Parallel: MT5634SMI-P-92
Medical Device: MT5634SMI-HV-92, MT5634SMI-P-HV-92
Industrial Temperature: MT5634SMI-ITP-92, MT5634SMI-P-ITP-92

PN S000263C, Version C
Copyright

This publication may not be reproduced, in whole or in part, without prior expres sed written
permission from Multi-Tech Systems, Inc. All rights reserved.
Copyright © 2003-4, by Multi-Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no represent ations or warranties with respect to the contents hereof
and specifically disclaim any implied warranties of merchantability or fitness for any particular
purpose. Furthermore, Multi-Tech Systems, Inc. reserves the right to revise this publication and to
make changes from time to time in the content hereof without obligation of Multi-Tech Systems, Inc.
to notify any person or organization of such revisions or changes.

Revisions

Revision Level Date Description

A 08/09/02 First release. Includes global configuration and V.92 protocol.
B 06/27/03 Add V.34 documentation. Updated the Serial Test/Demo Board graphic.

Updated the parts list. Updated Flash Programming Protocol. Updated
Telecom Approvals and Country Codes. Changed the product name
from ModemModule to SocketModem.

C 06/04/04 Create a separate Universal Socket Hardware guide and a separate AT

Command Reference Guide.

Trademarks

Trademarks of Multi-Tech Systems, Inc. are SocketModem and the Multi-Tech logo.
Microsoft and Microsoft Windows are either registered trademarks or trademarks of Microsoft
Corporation in the United States and/or other countries.

World Headquarters

Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, MN 55112
Phone: [phone] or 800-328-9717
Fax: [phone]

Technical Support
Country By Email By Phone

France: [e-mail] (33) 1-64 61 09 81
India: [e-mail] 91 (124) 6340778
U.K.: [e-mail] (44) 118 959 7774
U.S. and Canada: [e-mail] [phone]
Rest of the World: [e-mail] [phone]
Internet Address: http://www.multitech.com

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 2

Table of Contents

Contents

Chapter 1 – AT Commands, S-Registers and Result Codes ..................................................................5

Introduction................................................................................................................................................5

AT Command Summary ............................................................................................................................6

AT Commands...........................................................................................................................................8

Escape AT Commands............................................................................................................................21

V.92 Commands......................................................................................................................................22

S-Registers..............................................................................................................................................28

Result Codes ...........................................................................................................................................31

Chapter 2 – Fax Class 1 and Class 1.0 Commands...............................................................................33

Fax I/O Processing ..................................................................................................................................33

DTE-to-Modem Transmit Data Stream ...............................................................................................33

Modem-to-DTE Receive Data Stream ................................................................................................33

Fax Mode Selection.............................................................................................................................34

Fax Origination....................................................................................................................................34

Fax Answering.....................................................................................................................................34

Fax Control Transmission ...................................................................................................................34

Fax Control Reception.........................................................................................................................35

Fax Data Transmission .......................................................................................................................36

Fax Data Reception.............................................................................................................................36

Commands and Parameters....................................................................................................................37

Mode Entry Commands.......................................................................................................................37

Mode Commands................................................................................................................................37

Service Class 1 Commands ....................................................................................................................41

Examples.................................................................................................................................................45

Chapter 3 – Fax Class 2 and 2.0/2.1 Commands ...................................................................................48

Introduction..............................................................................................................................................48

AT Command Implementation.................................................................................................................49

Modes of Interaction ................................................................................................................................50

AT Command Mode............................................................................................................................50

Command Execution Mode.................................................................................................................52

Data Transfer Mode ............................................................................................................................52

Commands and Responses Overview ....................................................................................................55

Action Commands...............................................................................................................................55

Modem Responses .............................................................................................................................56

Parameters for Mandatory Services....................................................................................................57

Parameters for Optional Services.......................................................................................................58

Identification Commands.........................................................................................................................59

Service Class Indication......................................................................................................................59

Service Class Capabilities...................................................................................................................59

Service Class Selection.......................................................................................................................60

Request Manufacturer Identification ...................................................................................................60

Request Model Identification...............................................................................................................60

Request Revision Identification...........................................................................................................60

Action Commands....................................................................................................................................61

Originate a Call....................................................................................................................................61

Answer a Call ......................................................................................................................................61

Data Transmission ..............................................................................................................................62

Post-Page Message Release..............................................................................................................62

Data Reception....................................................................................................................................63

Session Termination............................................................................................................................63

Initialize Facsimile Parameters ...........................................................................................................63

Modem Responses..................................................................................................................................64

T.30 Phase A Negotiation Responses................................................................................................64

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Table of Contents

T.30 Phase B Negotiation Responses................................................................................................65

T.30 Phase C Page Reception Responses.........................................................................................68

T.30 Phase D Post Page Responses..................................................................................................69

Call Termination with Status................................................................................................................69

Parameter Commands.............................................................................................................................72

T.30 Session Parameters....................................................................................................................72

T.30 Procedure Control Parameters...................................................................................................82

Phase C Data Format Parameters......................................................................................................87

Miscellaneous Parameters..................................................................................................................92

Session Message Report Responses......................................................................................................93

Sample Modem Control Sessions ...........................................................................................................94

Send two pages, 1-D data, no errors (Class 2)...................................................................................94

Receive two pages, 1-D data, no errors (Class 2)..............................................................................95

Send two pages, 1-D data, no errors (Class 2.0)................................................................................96

Receive two pages, 1-D data, no errors (Class 2.0)...........................................................................97

Originate and send a two page facsimile with V.34 half-duplex (Class 2.1).......................................98

Answer and receive a two-page facsimile with V.34 half-duplex (Class 2.1)......................................99

Alphabetic List of Commands and Responses......................................................................................100

ASCII Conversion Chart.........................................................................................................................102

Chapter 4 – Voice Commands ...............................................................................................................103

Introduction............................................................................................................................................103

Voice S-Register Summary ...................................................................................................................104

Voice Commands...................................................................................................................................104

Commands That Change for Voice Mode Support................................................................................104

Voice +V Commands Summary.............................................................................................................105

Voice +V Commands Detail...................................................................................................................105

Interface Configuration Commands.......................................................................................................119

Flow Control...........................................................................................................................................121

Voice Mode Result Codes .....................................................................................................................121

Unsolicited Voice Mode Result Codes...................................................................................................122

Valid Complex Event Report Tags....................................................................................................122

Voice Mode Shielded Codes .................................................................................................................123

Sample Sessions...................................................................................................................................125

Sample Rate Selection and Suggested Compression Method.........................................................125

Answer Phone, Play Greeting Message, and Record Message Example........................................126

DTE/DCE Interface Rates......................................................................................................................128

Chapter 5 – Remote Configuration and Country Code Configuration ..............................................129

Remote Configuration............................................................................................................................129

Basic Procedure................................................................................................................................129

Setup.................................................................................................................................................129

Country Code Configuration ..................................................................................................................130

Using the Global Wizard Utility..........................................................................................................130

Using AT Commands........................................................................................................................130

Index.........................................................................................................................................................131

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 4

Chapter 1 – AT Commands, S-Registers and Result Codes

Chapter 1 – AT Commands, S-

Registers and Result Codes

Introduction

The AT commands are used to control the operation of your modem. They are called AT commands
because the characters AT must precede each command to get the ATtention of the modem.

AT commands can be issued only when the modem is in command mode or online command mode.

• The modem is in command mode whenever it is not connected to another modem.

• The modem is in data mode whenever it is connected to another modem and ready to exchange

data. Online command mode is a temporary state in which you can issue commands to the
modem while connected to another modem.

• To put the modem into online command mode from data mode, you must issue an escape

sequence (+++) followed immediately by the AT characters and the comm and, e.g., +++ATH to

hang up the modem. To return to data mode from online command mode, you must issue the
command ATO.

To send AT commands to the modem you must use a communications program, such as the
HyperTerminal applet in Windows 98 and NT 4.0, or some other available terminal program. You can
issue commands to the modem either directly, by typing them in the terminal window of the
communications program, or indirectly, by configuring the operating system or communications
program to send the commands automatically. Fortunately, communications programs make daily
operation of modems effortless by hiding the commands from the user. Most users, therefore, need to
use AT commands only when reconfiguring the modem, e.g., to turn auto answer on or off.

The format for entering an AT command is ATXn, where X is the command and n is the specific value
for the command, sometimes called the command parameter. The value is always a number. If the
value is zero, you can omit it from the command; thus, AT&W is equivalent to AT&W0. Most
commands have a default value, which is the value that is set at the factory. The default values are
shown in the “AT Command Summary” (See below).

You must press ENTER (it could be some other key depending on the terminal program) to send the
command to the modem. Any time the modem receives a command, it sends a response known as a
result code. The most common result codes are OK, ERROR, and the CONNECT messag es that the
modem sends to the computer when it is connecting to another modem. See a table of valid result
codes at the end of this chapter.

You can issue several commands in one line, in what is called a command string. The command
string begins with AT and ends when you press ENTER. Spaces to separate the commands are
optional; the command interpreter ignores them. The most familiar command string is the initialization
string, which is used to configure the modem when it is turned on or reset, or when your
communications software calls another modem.

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Chapter 1 – AT Commands, S-Registers and Result Codes

AT Command Summary

Organization of AT Commands on the following pages: 1st, by the initial command character (&, +, %)
2nd, alphabetized by the second command character (Except for listing of AT).

Command Description

AT
A
A/
Bn
Ds
DS=y
En
Fn
Hn
In
Mn
Nn
On
P
Qn
Sr=n
Sr?
T
Vn
Wn
Xn
Zn
&Cn
&Dn
&En
&Fn
&Gn
&Kn
&Ln
&Pn
&Qn
&Sn
&Tn
&V
&Wn
&Zy=x
\An
\Bn
\Kn
\Nn
\Qn
\Tn
\Vn

-Cn
%A
%B
%Cn
%DCn
%En
%Hn
%Rn
%Sn
$EBn

Attention Code
Answer
Repeat Last Command
Communication Standard Setting
Dial
Dial Stored Telephone Number
Echo Command Mode Characters
Echo Online Data Characters
Hook Control
Information Request
Monitor Speaker Mode
Modulation Handshake
Return Online to Data Mode
Pulse Dialing
Result Codes Enable/Disable
Set Register Value
Read Register Value
Tone Dialing
Result Code Format
Result Code Options
Result Code Selection
Modem Reset
Data Carrier Detect (DCD) Control
Data Terminal Ready (DTR) Control
XON/XOFF Pass-Through
Load Factory Settings
V.22bis Guard Tone Control
Flow Control Selection
Leased Line Operation
Pulse Dial Make-to-Break Ratio Selection
Asynchronous Communications Mode
Data Set Ready (DSR) Control
Loopback Test (V.54 Test) Commands
Display Current Settings
Store Current Configuration
Store Dialing Command
Select Maximum MNP Block Size
Transmit Break
Break Control
Error Correction Mode Selection
Flow Control Selection
Inactivity Timer
Protocol Result Code
Data Calling Tone
Adaptive Answer Result Code Enable
View Numbers in Blacklist
Data Compression Control
AT Command Control
Fallback and Fall Forward Control
Direct Connect Enable
Cisco Configuration
Command Speed Response
Asynchronous Word Length

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command Description

$Dn
$MBn
$SBn
#CBAn
#CBDn
# CBF?
# CBFR
# CBIn
# CBNy=n
# CBPn
# CBRy
# CBSn
#Pn
#Sx
#S=x
+VDR=x, y
+++AT<CR>
%%%ATMTSMODEM<CR>
V.92 Commands

DTR Dialing
Online BPS Speed
Serial Port Baud Rate
Callback Attempts
Callback Delay
Callback Failed Attempts Display
Callback Failed Attempts Reset
Local Callback Inactivity Timer
Store Callback Password
Callback Parity
Callback Security Reset
Callback Enable/Disable
Set 11-bit Parity
Enter Setup Password
Store Setup Password
Distinctive Ring Report
Escape Sequence
Remote Configuration Escape Sequence

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Chapter 1 – AT Commands, S-Registers and Result Codes

AT Commands

Command: AT Attention Code

Values: N/A
Description: The attention code precedes all command lines except A/, A: and escape

sequences.

Command: ENTER Key

Values: N/A
Description: Press the E

Command: A Answer

Values: N/A
Description: Answer call before final ring.

Command: A/ Repeat Last Command

Values: N/A
Description: Repeat the last comm and string. Do not precede this command with AT. Do not

press E

Command: Bn Communication Standard Setting

Values: n = 0–3, 15, 16
Default: 0 and 15
Description: B0 Select ITU-T V.22 mode when modem is at 1200 bps.
B1 Select Bell 212A when modem is at 1200 bps.
B2 Deselect V.23 reverse channel (same as B3).
B3 Deselect V.23 reverse channel (same as B2).
B15 Select V.21 when the modem is at 300 bps.
B16 Select Bell 103J when the modem is at 300 bps.

NTER (RETURN) key to execute most commands.

NTER to execute.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: Ds Dial

Values: s = dial string (phone number and dial modifiers)
Default: none
Description: Dial telephone number s, where s may up to 40 characters long and include the 0–

9, *, #, , B, C, and D characters, and the L, P, T, V, W, S, comma (,), semicolon (;),
!, @, ^ and $ dial string modifiers.

Dial string modifiers:
L Redial last number. (Must be placed immediately after ATD.)
P Pulse-dial following numbers in command.
T Tone-dial following numbers in comm and (default).
V Switch to speakerphone mode and dial the following number. Use ATH

command to hang up.

W Wait for a new dial tone before continuing to dial. (X2, X4, X5, X6, or X7 must

be selected.)

, Pause during dialing for time set in register S8.
; Return to command mode after dialing. (Place at end of dial string.)
! Hook flash. Causes the modem to go on-hook for one-half second, then off-

hook again.

@ Wait for quiet answer. Causes modem to wait for a ringback, then 5 seconds

of silence, before processing next part of command. If silence is not detected,
the modem returns a NO ANSWER code.

^ Disable data calling tone transmission.
$ Detect AT&T call card “bong” tone. The character should follow the phone

number and precede the user’s call card number:

ATDT1028806127853500$

123456789

Command: DS=y Dial Stored Telephone Number

Values: n = 0–2 (0–1 for SMI-Parallel {internal})
Default: none
Description: Dial a number previousl y stored in directory number y by the &Zy=x command.

Example: ATDS=2

Command: En Echo Command Mode Characters

Values: n = 0 or 1
Default: 1
Description: E0 Do not echo keyboard input to the terminal.
E1 Do echo keyboard input to the terminal.

Command: Fn Echo Online Data Characters

Values: n = 1
Default: 1
F0 Enable online data character echo. (Not supported.)
F1 Disable online data character echo (included for backward compatibility with

some software).

Command: Hn Hook Control

Values: n = 0 or 1
Default: 0
Description: H0 Go on-hook (hang up).
H1 Go off-hook (make the phone line busy).

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: In Information Request

Values: n = 0–5, 9, 11
Default: None
Description: I0 Display default speed and controller firmware version.
I1 Calculate and display ROM checksum (e.g., 12AB).
I2 Check ROM and verify the checksum, displaying OK or ERROR.
I3 Display default speed and controller firmware version.
I4 Display firmware version for data pump (e.g., 94).
I5 Display the board ID: software version, hard wa re version, an d country ID
I9 Display the country code (e.g., NA Ver. 1).
I11 Display diagnostic information for the last modem connection, such as DSP

and firmware version, link type, line speed, serial speed, type of error
correction/data compression, number of past retrains, etc.

Command: Mn Monitor Speaker Mode

Values: n = 0, 1, 2, or 3
Default: 1
Description: M0 Speaker always off.
M1 Speaker on until carrier signal detected.
M2 Speaker always on when modem is off-hook.
M3 Speaker on until carrier is detected, except while dialing.

Command: Nn Modulation Handshake

Values: n = 0 or 1
Default: 1
Description: N0 Modem performs handshake only at communication standard specified by

S37 and the B command.

N1 Modem begins handshake at communication standard specified by S37 and

the B command. During handshake, fallback to a lower speed can occur.

Command: On Return Online to Data Mode

Values: 0, 1, 3
Default: None
Description: O0 Exit online command mode and return to data mode (see +++AT<CR>

escape sequence).
O1 Issue a retrain and return t o online data mode.
O3 Issue a rate renegotiations and return to data mode.

Command: P Pulse Dialing

Values: P, T
Default: T
Description: Configures the modem for pulse (non-touch-tone) dialing. Dialed digits are pulsed

until a T command or dial modifier is received.

Command: Qn Result Codes Enable/Disable

Values: n = 0 or 1
Default: 0
Description: Q0 Enable result codes.
Q1 Disable result codes.
Q2 Returns an OK for backward compatibility with some software.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: Sr=n Set Register Value

Values: r = S-register number; n varies
Default: None
Description: Set value of register Sr to value of n, where n is entered in decimal format (e.g.,

S0=1).

Command: Sr? Read Register Value

Values: r = S-register number
Default: None
Description: Read value of register Sr and display it in 3-digit decimal form (e.g., S2? gives the

response 043).

Command: T Tone Dialing

Values: P, T
Default: T
Description: Configures the modem for DTMF (touch-tone) dialing. Dialed digits are tone dialed

until a P command or dial modifier is received.

Command: Vn Result Code Format

Values: n = 0 or 1
Default: 1
Description: V0 Displays result codes as digits (terse response).
V1 Displays resu lt codes as words (verbose response).

Command: Wn Result Code Options

Values: n = 0, 1, or 2
Default: 2
Description: W0 CONNECT result code reports serial port speed, disables protocol result

codes.
W1 CONNECT result code reports serial port speed, enables protocol result

codes.
W2 CONNECT result code reports line speed, enables protocol result codes.

Command: Xn Result Code Selection

Values: n = 0–7
Default: 4
Description: X0 Basic result codes (CONNECT); does not look for dial tone or busy signal.
X1 Extended result codes (CONNECT 46000 V42bis); does not look for dial tone

or busy signal.
X2 Extended result codes with NO DIALTONE; does not look for busy signal.
X3 Extended result codes with BUSY; does not look fo r dial tone.
X4 Extended result codes with NO DIALTONE and BUSY.
X5 Extended result codes with NO DIALTONE and BUSY.
X6 Extended result codes with NO DIALTONE and BUSY.
X7 Basic result codes with NO DIALTONE and BUSY.

Command: Zn Modem Reset

Values: n = 0 or 1
Default: None
Description: Z0 Re set modem to profile saved by the last &W command.
Z1 Same as Z0.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: &Cn Data Ca rri er Detect (DCD) Control

Values: n = 0, 1, 2
Default: 1
Description: &C0 Forces the DCD circuit to be always ON.
&C1 DCD goes ON when the remote modem’s carrier signal is detected, and

goes OFF when the carrier signal is not detected.

&C2 DCD turns OFF upon disconnect for time set by S18. It then goes high again

(for some PBX phone systems).

Command: &Dn Data Terminal Ready (DTR) Control

Values: n = 0, 1, 2, or 3
Default: 2
Description: &D0 Modem ignores true status of DTR signal and responds as if it is always on.
&D1 If DTR drops while in online data mode, the modem enters command mode,

issues an OK, and remains connected.

&D2 If DTR drops while in online data mode, the modem hangs up. If the signal is

not present, the modem will not answer or dial.

&D3 If DTR drops, modem hangs up and resets as if ATZ command were issued.

Command: &En XON/XOFF Pacing Control

Values: n = 12 or 13
Default: 12
Description: &E12 Disables XON/XOFF pacing.
&E13 Enables XON/XOFF pacing.

Command: &Fn Load Factory Settings

Values: n = 0
Default: None
Description: &F0 Load factory settings as active configuration.

Note: See also the Z command.

Command: &Gn V.22bis Guard Tone Control

Values: n = 0, 1, or 2
Default: 0
Description: &G0 Disable guard tone.
&G1 Set guard tone to 550 Hz.
&G2 Set guard tone to 1800 Hz.

Note: The &G command is not used in North America.

Command: &Kn Flow Control Selection

Values: n = 0, 3, or 4
Defaults: 3
Description: &K0 Disable flow control.
&K3 Enable CTS/RTS hardware flow control.
&K4 Enable XON/XOFF software flow control.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: &Ln Leased Line Operation

Values: n = 0, 1, or 2
Defaults: 0
Description: &L0 The modem is set for standard dial-up operation.
&L1 The modem is set for leased line operation in originate mode.
&L2 The modem is set for leased line operation in answer mode.

Note: For &L1 and &L2, there is a 30-second window between power up and the

starting of the leased line handshake. During this time, you can turn off the
command, if desired.

Command: &Pn Pulse Dial Make-to-Break Ratio Selection

Values: n = 0, 1, or 2
Default: 0
Description: &P0 60/40 make-to-break ratio
&P1 67/33 make-to-break ratio
&P2 20 pulses per second

Note: The &P2 command is available only if the country code is set to Japan.

Command: &Qn Asynchronous Communications Mode

Values: n = 0, 5, 6, 8, or 9
Default: 5
Description: &Q0 Asynchronous with data buffering. Same as \N0.
&Q5 Error control with data buffering. Same as \N3.
&Q6 Asynchronous with data buffering. Same as \N0.
&Q8 MNP error control mode. If MNP error control is not established, the modem

falls back according to the setting in S36.

&Q9 V.42 or MNP error control mode. If neither error control is established, the

modem falls back according to the setting in S36.

Command: &Sn Data Set Ready (DSR) Control

Values: n = 0 or 1
Default: 0
Description: &S0 DSR is always ON.
&S1 DSR goes ON only during a connection.

Command: &Tn Loopback Test (V.54 Test) Commands Values: n = 0, 1, 3, 6

Default: None
Description: The modem can perform selected test and diagnostic functions. A test can be run

only when the modem is operating in non-error-correction mode (normal or direct
mode). For tests 3 and 6, a connection between the two modems must be
established. To terminate a test in progress, the escape sequence (+++AT) must

be entered.
&T0 Stops any test in progress.
&T1 Starts a local analog loopback, V.54 Loop 3, test. If a connection exists when

this command is issued, the modem hangs up. When the test starts, a
CONNECT message is displayed.

&T3 Starts local digital loopback, V.54 Loop 2, test. If no connection exists,

ERROR is returned.

&T6 Initiates a remote digital loopback, V.54 Loop 2, test without self-test. If no

connection exists, ERROR is returned.

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 13

Chapter 1 – AT Commands, S-Registers and Result Codes

Command: &V Display Current Settings

Values: N/A
Description: Displays the active modem settings.

Command: &Wn Store Current Configuration

Values: n = 0 or 1
Default: 1
Description: &W0 Stores current modem settings in non-volatile memory and causes them to

be loaded at power-on or following the ATZ command instead of the
factory defaults. See &F command.

&W1 Clears user default settings from non-volatile memory and causes the

factory defaults to be loaded at power-on or following the ATZ command.

Command: &Zy=x Store Dialing Command

Values: y = 0–2 (0–1SMI-Parallel {internal})
x = Dialing command
Default: None
Description: Stores dialing command x in memory location y. Dial the stored number using the

command ATDS=y. See Also the #CBS command, a callback security command.

Command: \An Select Maximum MNP Block Size

Values: n = 0, 1, 2, or 3
Default: 3
Description: \A0 64-character maximum
\A1 128-character maximum
\A2 192-character maximum
\A3 256-character maximum

Command: \Bn Transmit Break

Values: n = 0–9 in 100 ms units
Default: 3
Description: In non-error-correction mode only, sends a break signal of the specified length to a

remote modem. Works in conjunction with the \K command.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: \Kn Break Control

Values: n = 0–5
Default: 5
Description: Controls the modem 's response to a break received from: computer, remote

modem, or \B command. Response is different for each of three different states.
Data mode. Modem receives the break from the computer:
\K0 Enter online command mode, no break sent to the remote modem.
\K1 Clear data buffers and send break to the remote modem.
\K2 Same as \K0.
\K3 Send break immediately to the remote modem.
\K4 Same as \K0.
\K5 Send break to the remote modem in sequence with the transmitted data.
Data mode. Modem receives the break from the remote modem:
\K0 Clear data buffers and send break to the computer.
\K1 Same as \K0.
\K2 Send break immediately to the computer.
\K3 Same as \K2.
\K4 Send break to the computer in sequence with the received data.
\K5 Same as \K4.
Online command mode. Modem receives a \Bn command from the computer:
\K0 Clear data buffers and send break to the remote modem.
\K1 Same as \K0.
\K2 Send break immediately to the remote modem.
\K3 Same as \K2.
\K4 Send break to the remote modem in sequence with the transmitted data.
\K5 Same as \K4.

Command: \Nn Error Correction Mode Selection

Values: n = 0–5, or 7
Default: 3
Description: \N0 Non-error correction mode with data buffering (buffer mode; same as &Q6).
\N1 Direct mode.
\N2 MNP reliable mode. If the modem cannot make an MNP connection, it

disconnects.

\N3 V.42/MNP auto-reliable mode. The modem attempts first to connect in V.42

error correction mode, then in MNP mode, and finally in non-error correction
(buffer) mode with continued operation.

\N4 V.42 reliable mode. If the modem cannot make a V.42 connection, it

disconnects.
\N5 V.42, MNP, or non-error correction (same as \ N3).
\N7 V.42, MNP, or non-error correction (same as \ N3).

Command: \Qn Flow Control Selection

Values: n = 0, 1, or 3
Default: 3
Description: \Q0 Disable flow control (same as &K0).
\Q1 XON/XOFF software flow control (same as &K4).
\Q2 CTS-only flow control. Not supporte d.
\Q3 RTS/CTS hardware flow control (same as &K3).

Command: \Tn Inactivity Timer

Values: n = 0, 1–255
Default: 0
Description: Sets the time (in minutes) after the last character is sent or received that the

modem waits before disconnecting. A value of zero disables the timer. Applies only
in buffer mode.

Note: You can also set the inactivity timer by changing the value of S30.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: \Vn Protocol Result Code

Values: n = 0, 1, or 2
Default: 1
Description: \V0 Disables the appending of the protocol result code to the DCE speed.
\V1 Enables the appending of the protocol result code to the DCE speed.
\V2 Same as \V1.

Command: \Xn XON/XOFF Pass-Through

Values: n = 0 or 1
Default: 0
Description: \X0 Modem responds to and discards XON/XOFF charac ters.
\X1 Modem responds to and passes XON/XOFF characters.
Note: This is also controlled via &E6 and &E7.

Command: -Cn Data Calling Tone

Values: n = 0 or 1
Defaults: 1
Description: -C0 Disable V.25 data calling tone to deny remote data/fax/voice discrimination.

-C1 Enable V.25 data calling tone to allow remote data/fax/voice discrimination.

Command: %A Adaptive Answer Result Code Enable

Values: n = 0 or 1
Default: 0
Description: The %A command control s wh ether the DATA or FAX result codes will be sent by

the modem. The modem must be in fax mode for this command to work. Also, the
modem must be set to +FAA=1, which enables the modem to distinguish between
a fax and a data call. When these commands are enabled, the modem sends
DATA to the computer when it detects data tones and FAX when it detects fax
tones. These strings are used by some servers to select the appropriate

communication program.
%A0 Disables adaptive answer result codes.
%A1 Enables adaptive answer result codes.

Command: %B View Numbers in Blacklist

Values: N/A
Description: If blacklisting is in effect, AT%B displays the numbers for whi ch the last call

attempted in the previous two hours failed. In countries that do not require

blacklisting, the ERROR result code appears.

Command: %Cn Data Compression Control

Values: n = 0 or 1
Default: 1
Description: %C0 Disable V.42bis/MNP 5 data compression.
%C1 Enable V.42bis/MNP 5 data compression.

Command: %DCn AT Command Control

Values: n = 0 or 1
Default: 0
Description: %DC0 The modem responds to AT commands.
%DC1 The modem ignores AT commands.

Note: The modem will respond to AT%DC for 10 seconds after power-up.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: %En Fallback and Fall Forward Control

Values: n = 0, 1, or 2
Default: 2
Description: %E0 Disable fallback and fall forward.
%E1 Enable fallback, disable fall forward.
%E2 Enable fallback and fall forward.

Command: %Hn Direct Connect Enable

Values: n = 0, 1
Default: 0
Description: %H0 Sets callback security to normal operation.
%H1 All callback security calls will be direct connect regardless of whether the

password or phone number has the - character.

Command: %Rn Cisco Configuration

Values: n = 0, 1
Default: 0
Description: %R0 Disables Cisco configuration.
%R1 Sets E0, Q1, &D0, \N0, $SB9600, and %S1 for operation with a Cisco

router.

Command: %Sn Command Speed Response

Values: n = 0, 1
Default: 0
Description: %S0 Sets modem to respond to AT commands at all normal speeds.
%S1 AT commands accepted at 115200 bps only. Commands at other speeds

are ignored.

Command: $Dn DTR Dialing

Values: n = 0 or 1
Default: 0
Description: $D0 Disables DTR dialing.
$D1 Dials the number in memory location 0 when DTR goes high.

Command: $EBn Asynchronous Word Length

Values: n = 0 or 1
Default: 0
Description: $EB0 Enables 10-bit mode.
$EB1 Enables 11-bit mode.

Command: $MBn Online BPS Speed

Values: n = speed in bits per second
Default: 28,800
Description: $MB75 Selects CCITT V.23 mode
$MB300 Selects 300 bps on-line
$MB1200 Selects 1200 bps on-line
$MB2400 Selects 2400 bps on-line
$MB4800 Selects 4800 bps on-line
$MB9600 Selects 9600 bps on-line
$MB14400 Selects 14400 bps on-line
$MB19200 Selects 19200 bps on-line
$MB28800 Selects 28800 bps on-line
$MB33600 Selects 33600 bps on-line

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: $RPn Ring Priority vs. AT Command Priority

Values: n = 0 or 1
Default: 1
Description: $RP0 The AT command will have priority over the ring. S1 will be reset to 0

if an AT command is received. This command is storable to memory.

$RP1 The ring will have priority over the AT command. S1 will increment

even if an AT command and ring are received together and the incoming
call will be answered when S1 is equal to S0.

Note: SocketModems do not detect ring cadence of TelTone teleph one

line simulators as a valid ring.

Command: $SBn Serial Port Baud Rate

Values: n= speed in bits per se cond
Default: 57600

Description: $SB300 Sets serial port to 300 bps

$SB1200 Sets serial po rt to 1200 bps

$SB2400 Sets serial po rt to 2400 bps
$SB4800 Sets serial po rt to 4800 bps
$SB9600 Sets serial po rt to 9600 bps
$SB19200 Sets serial port to 19200 bps
$SB38400 Sets serial port to 38400 bps
$SB57600 Sets serial port to 57600 bps
$SB115200 Sets serial port to 115200 bps
$SB230400 Sets serial port to 230400 bps

Command: +VDR=x, y Distinctive Ring Report

Values: x = 0, 1 Distinctive Ring report control. See description.
y = 0–255 Minimum ring interval in 100 ms units. See description.
Default: 0, 0
Description: Enables reporting of ring cadence information to the DTE and specifies the

minimum ring cadence that will be reported.

The report format is one line per silence period and one line per ring period.

The length of the silence period is in the form DROF=number in units of 100
ms<CR><LF>, and the length of the ring is in the form DRON=number in
units of 100 ms<CR> <LF>. The modem may produce a Ring event code
after the DRON message if enabled by the y parameter. The y parameter
must be set to a value equal to or smaller than the expected ring cadence in

order to pass the report to the DTE.
+VDR=0, N/A Disables Distinctive Ring cadence reporting.
+VDR=1, 0 Enables Distinctive Ring cadence reporting. Other call

progress result codes (including RING) are reported as
normal.

+VDR=1, >0 Enables Distinctive Ring cadence reporting. The RING result

code is reported after the falling edge of the ring pulse (i.e.,

after the DRON report).
+VDR=? Displays the allowed values.
+VDR? Displays the current value.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: #CBAn Callback Attempts

Values: n = 1–255
Default: 4
Description: Sets the number of callback attempts that are allowed after passwords have

been exchanged between modems.

Command: #CBDn Callback Delay

Values: n = 0–255
Default: 15
Description: Sets the length of time (in seconds) that the modem waits before calling back

the remote modem.

Command: #CBF? Callback Failed Attempts Display

Values: N/A
Default: N/A
Description: Requests the number of failed callback passwords since reset or power-up.

This number can be stored to nonvolatile memory using the &W command.

Command: #CBFR Callback Failed Attempts Reset

Values: N/A
Default: N/A
Description: Resets the number of failed callback passwords to 0. This does not reset the

number stored in nonvolatile memory.

Command: #CBIn Local Callback Inactivity Timer

Values: n = 1–255
Default: 20
Description: Sets the time (in minutes) that the modem waits for a command before

forcing the user to enter the setup password again.

Command: #CBNy=x Store Callback Password

Values: y = 0–29

x = password
Defaults: None
Description: Sets the callback security password for the y memory location. The password

must have 6 to 10 characters, and cannot include the + or - charact ers.

Command: #CBPn Callback Parity

Values: n = 0, 1, or 2
Default: 0
Description: Sets parity for the callback security messages.
#CBP0 No parity.
#CBP1 Odd parity.
#CBP2 Even parity.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: #CBRy Callback Security Reset

Values: y = 0–29
Default: None
Description: Clears the password and phone number in the y memory location.

Command: #CBSn Callback Enable/Disable

Values: n = 0, 1, 2, or 3
Default: 0
Description: #CBS0 Disables callback security.
#CBS1 Enables local and remote callback security.
#CBS2 Enables remote callback security only.
#CBS3 Disables callback security until local hang-up or reset.

Command: #Pn Set 11-bit Parity

Values: n = 0 or 1
Default: 2
Description: #P0 No parity.
#P1 Odd parity.
#P2 Even parity.

Command: #Sx Enter Setup Password

Values: x= password (1–8 characters, case sensitive)
Default: MTSMODEM
Description: Enters the remote configuration setup password.

Command: #S=x Store Setup Password

Values: x= password (1–8 characters, case sensitive)
Default: MTSMODEM
Description: Stores a new remote configuration setup password.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Escape AT Commands

Command: +++AT<CR> Escape Sequence

Values: N/A
Description: Puts the modem in command mode (and optionally issues a command)

while remaining online. Type +++AT and up to six optional command
characters; then press ENTER. Used mostly to issue the hang-up
command: +++ATH<CR>.

Command: %%%ATMTSMODEM<CR> Remote Configuration Escape Sequence

Values: N/A
Description: Initiates remote configuration mode while online with remote modem.

The remote configuration escape character (%) is defined in register
S13.

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Chapter 1 – AT Commands, S-Registers and Result Codes

V.92 Commands

Command: +MS= Modulation Selection

Values: See description.
Defaults: See description.
Description: This extended-format command selects modulation, enables or disables automode,

and specifies the highest downstream and upstream connection rates using one to
four subparameters.

The command syntax is

+MS=[mod][,[automode][,[0][,[max_rate][,[0][,[max_rx_rate]]]]]]<CR>
Subparameters that are not entered retain their current value. Commas separate
optional subparameters, and must be inserted to skip a subparameter. Exampl e:
+MS=,0<CR> disables automode and keeps all other settings at their current
values.

+MS=? Reports supported options in the format (list of supported mod values),(list of

supported automode values),(0),(list of supported max_rate values),(0),(list of
supported max_rx_rate values). Example: +MS: (BELL103, V21, BELL212A, V22,
V22B, V23C, V32, V32B, V34, V90, V92), (0, 1), (0), (0-33600), (0), (0-56000)

+MS? Reports current options in the format mod, automode, 0, max_rate, 0, max_rx_rate.

Example: +MS: V92, 1, 0, 31200, 0, 56000.

Subparameters

mod Specifies the preferred modulation (automode enabled) or the modulation to use in

originating or answering a connection (automode disabled). The default is V92.

mod Modulation Possible rates (bps)

V922 V92 56000, 54666, 53333, 52000, 50666, 49333,

48000, 46666, 45333, 44000, 42666, 41333.
40000, 38666, 37333, 36000, 34666, 33333,
32000, 30666, 29333, or 28000

V903 V.90 56000, 54666, 53333, 52000, 50666, 49333,

48000, 46666, 45333, 44000, 42666, 41333.
40000, 38666, 37333, 36000, 34666, 33333,
32000, 30666, 29333, or 28000

V34 V.34 33600, 31200, 28800, 26400, 24000,

21600,19200, 16800, 14400, 12000, 9600, 7200,

4800, or 2400
V32B V.32bis 14400, 12000, 9600, 7200, or 4800
V32 V.32 9600 or 4800
V22B V.22bis 2400 or 1200
V22 V.22 1200
V23C V.23 1200
V21 V.21 300

Bell212A Bell 212A 1200
Bell103 Bell 103 300

Notes:

1. See optional <automode>, <max_rate>, and <max_RX_rate>

2. Selects V.92 modulation as first priority. If a V.92 connection

3. Selects V.90 modulation as first priority. If a V.90 connection

subparameters.

cannot be established, the modem attempts V.90, V.34, V.32bis, etc.
cannot be established, the modem attempts V.34, V.32bis, etc.

automode An optional numeric value that enables or disables automatic modulation

negotiation using V.8 bis/V.8 or V.32 bis Annex A. Automode is disabled if values
are specified for the max_rate and max_rx_rate parameters. The options are:

0 Disable automode

1 Enable automode (default)

1

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Chapter 1 – AT Commands, S-Registers and Result Codes

max_rate An optional number that specifies the highest rate at which the modem may establish an

upstream (transmit) connection. The value is decimal coded in units of bps, for example,
33600 specifies the highest rate to be 33600 bps.

0 Maximum rate determined by the modulation selected in mod (default).

300–33600 Maximum rate value limited by the modulation selected in mod. For valid max_rate values

for each mod value, see the following table.

mod value Valid max_rate values (bps)

V92, V90, V34 31200, 28800, 26400, 24 000, 216 00,19 200, 16800,

14400, 12000, 9600, 7200, 4800, 2400
V32B 19200, 16800, 14400, 12000, 9600, 7200, 4800
V32 14400, 12000, 9600, 7200, 4800
V22B 2400
V22, V23C, Bell212A 1200
V21, Bell103 300

max_rx_rate An optional number that specifies the highest rate at which the modem may establish a

downstream (receive) connection. The value is decimal coded in units of bps, e.g., 28800
specifies the highest rate to be 28800 bps.

0 Maximum rate determined by the modulation selected in mod (default).

300–56000 Maximum rate value limited by the modulation selected in mod. See “Possible

rates” in the mod table.

Command: +PCW=n Call Waiting Enable

Values: n = 0, 1, or 2
Default: 2
Description: Controls the action to be taken upon detection of a call waiting tone in V.92

mode. Values specified by this command are not modified when an AT&F
command is issued.

+PCW=0 Toggles V.24 Circuit 125 and collects Caller ID if enabled by

+VCID
+PCW=1 Hangs up
+PCW=2 Ignores V.92 call waiting
+PCW=? Displays the allowed values
+PCW? Displays the current value

Command: +PIG=n PCM Upstream Ignore

Values: n = 0 or 1
Default: 1
Description: Controls the use of PCM upstream during V.92 operation. PCM upstream

allows faster upload speeds to a V.92 server.
+PIG=0 Disables PCM upstream
+PIG=1 Enables PCM upstream
+PIG=? Displays the allowed values
+PIG? Displays the current value

Command: +PMH=n Modem on Hold Enable

Values: n = 0 or 1
Default: 1
Description: Controls if modem on hold procedures are enabled during V.92 operation.

Normally controlled by a modem on hold program. Values specified by this

command are not modified when an AT&F command is issued.
+PMH=0 Enables V.92 modem on hold
+PMH=1 Disables V.92 modem on hold
+PMH=? Displays the allowed values
+PMH? Displays the current value

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: +PMHF V.92 Modem Hook Flash

Values: N/A
Default: N/A
Description: Causes the DCE to go on-hook for a specified period of time, and then return

off-hook for at least a specified period of time. The specified period of time is

normally one-half second, but may be governed by national regula t ions.

“ERROR” is returned if MOH is not enabled.

Command: +PMHR=n Modem on Hold Initiate

Values: n = 0–13
Default: 0
Description: +PMHR is an action command that causes the modem to initiate MOH with

the central site modem. It returns the following values to indicate what has

been negotiated. Valid only if MOH is enabled and the modem is off-hook or

in data mode. Otherwise, ERROR will be returned.

+PMHR=0 Deny MOH request

+PMHR=1 Grant MOH request with 10 second timeout

+PMHR=2 Grant MOH request with 20 second timeout

+PMHR=3 Grant MOH request with 30 second timeout

+PMHR=4 Grant MOH request with 40 second timeout

+PMHR=5 Grant MOH request with 1 minute timeout

+PMHR=6 Grant MOH request with 2 minute timeout

+PMHR=7 Grant MOH request with 3 minute timeout

+PMHR=8 Grant MOH request with 4 minute timeout

+PMHR=9 Grant MOH request with 6 minute timeout

+PMHR=10 Grant MOH request with 8 minute timeout

+PMHR=11 Grant MOH request with 12 minute timeout

+PMHR=12 Grant MOH request with 16 minute timeout

+PMHR=13 Grant MOH request with indefinite timeout

+PMHR=? Displays the allowed values

+PMHR? Displays the current value

Command: +PMHT=n Modem on Hold Timer

Values: n = 0–13
Default: 0
Description: Determines if the modem will accept a V.92 Modem on Hold (MOH) request

and will set the MoH timeout.

+PMHT=0 Deny MOH request

+PMHT=1 Grant MOH request with 10 second timeout

+PMHT=2 Grant MOH request with 20 second timeout

+PMHT=3 Grant MOH request with 30 second timeout

+PMHT=4 Grant MOH request with 40 second timeout

+ P M H T= 5 Gr a n t M O H r e q u e s t w i t h 1 m i n u t e t i m eout

+PMHT=6 Grant MOH request with 2 minute timeout

+PMHT=7 Grant MOH request with 3 minute timeout

+PMHT=8 Grant MOH request with 4 minute timeout

+PMHT=9 Grant MOH request with 6 minute timeout

+PMHT=10 Grant MOH request with 8 minute timeout

+PMHT=11 Grant MOH request with 12 minute timeout

+PMHT=12 Grant MOH request with 16 minute timeout

+PMHT=13 Grant MOH request with indefinite timeout

+PMHT=? Displays the allowed values

+PMHT? Displays the current value

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: +PQC=n Quick Connect Control

Values: n = 0, 1, 2, or 3
Default: 3
Description: Controls V.92 shortened Phase 1 and Phase 2 startup procedures (Quick

Connect). When line conditions are stable, quick connect results in sho rten ed

connect times; however, significant fluctuation in line conditions from call to

call can cause longer connect times; thus, it may be advisable to disable

quick connect.

+PQC=0 Enables Short Phase 1 and Short Phase 2 (Quick Connect)
+PQC=1 Enables Short Phase 1
+PQC=2 Enables Short Phase 2
+PQC=3 Disables Short Phase 1 and Short Phase 2

+PQC=? Displays the allowed values

+PQC? Displays the current value

Command: +VCID=n Caller ID Selection

Values: n = 0, 1, or 2
Default: 0
Description: Enables Caller ID detection and configures the reporting and presentation of

the Caller ID data that is detected after the first ring. The reported data

includes the date and time of the call, the caller's name and number, and a

message. Set S0=2.

+VCID=0 Disables Caller ID
+VCID=1 Enables Caller ID with formatted data
+VCID=2 Enables Caller ID with unformatted data
+VCID=? Displays the allowed values
+VCID? Displays the current value

Command: +VDR=x, y Distinctive Ring Report

Values: x = 0, 1 Distinctive Ring report control. See description.
y = 0–255 Minimum ring interval in 100 ms units. See description.
Default: 0, 0
Description: Enables reporting of ring cadence information to the DTE and specifies the

minimum ring cadence that will be reported.

Report format is one line per silence period and one line per ring period. The

length of the silence period is in the form DROF=number in units of 100

ms<CR><LF>, and the length of the ring is in the form DRON=number in

units of 100 ms<CR> <LF>. The modem may produce a Ring event code

after the DRON message if enabled by the y parameter. The y parameter

must be set to a value equal to or smaller than the expected ring cadence in

order to pass the report to the DTE.

+VDR=0, N/A Disables Distinctive Ring cadence reporting.
+VDR=1, 0 Enables Distinctive Ring cadence reporting. Other call

progress result codes (including RING) are reported as normal.

+VDR=1, >0 Enables Distinctive Ring cadence reporting. RING result

code is reported after falling edge of the ring pulse (after the DRON

report).
+VDR=? Displays the allowed values.
+VDR? Displays the current value.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: #CBAn Callback Attempts

Values: n = 1–255
Default: 4
Description: Sets the number of callback attempts that are allowed after passwords have

been exchanged between modems.

Command: #CBDn Callback Delay

Values: n = 0–255
Default: 15
Description: Sets the length of time (in seconds) that the modem waits before calling back

the remote modem.

Command: #CBF? Callback Failed Attempts Display

Values: N/A
Default: N/A -
Description: Requests the number of failed callback passwords since reset or power-up.

This number can be stored to nonvolatile memory using the &W command.

Command: #CBFR Callback Failed Attempts Reset

Values: N/A
Default: N/A
Description: Resets the number of failed callback passwords to 0. This does not reset the

number stored in nonvolatile memory.

Command: #CBIn Local Callback Inactivity Timer

Values: n = 1–255
Default: 20
Description: Sets the time (in minutes) that the modem waits for a command before

forcing the user to enter the setup password again.

Command: #CBNy=x Store Callback Password

Values: y = 0–29

x = password
Defaults: None
Description: Sets the callback security password for the y memory location. The password

must have 6 to 10 characters, and cannot include the + or - charact ers.

Command: #CBPn Callback Parity

Values: n = 0, 1, or 2
Default: 0
Description: Sets parity for the callback security messages.
#CBP0 No parity.
#CBP1 Odd parity.
#CBP2 Even parity.

Command: #CBRy Callback Security Reset

Values: y = 0–29
Default: None
Description: Clears the password and phone number in the y memory location.

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Chapter 1 – AT Commands, S-Registers and Result Codes

Command: #CBSn Callback Enable/Disable

Values: n = 0, 1, 2, or 3
Default: 0
Description: #CBS0 Disables callback security.
#CBS1 Enables local and remote callback security.
#CBS2 Enables remote callback security only.
#CBS3 Disables callback security until local hang-up or reset.

Command: #Pn Set 11-bit Parity

Values: n = 0 or 1
Default: 2
Description: #P0 No parity.
#P1 Odd parity.
#P2 Even parity.

Command: #Sx Enter Setup Password

Values: x= password (1–8 characters, case sensitive)
Default: MTSMODEM
Description: Enters the callback security setup password.

Command: #S=x Store Setup Password

Values: x= password (1–8 characters, case sensitive)
Default: MTSMODEM
Description: Stores a new callback security and remote configuration setup password.

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Chapter 1 – AT Commands, S-Registers and Result Codes

S-Registers

Certain modem values, or parameters, are stored in memory locations called S-Registers. Use the S
command to read or to alter the contents of S-Registers (see previous section).

Register Unit Range Default Description
S0 1 ring 0, 1–255 1 Sets the number of rings until the modem answers. ATS0=0

disables auto answer completely.

S1 1 ring 0–255 0 Counts the rings that have occurred.
S2 decimal 0–127 43 (+) Sets ASCII code for the escape sequence character.

128–255 Values greater than 127 disable escape.

S3 decimal 0–127 13 (^M) Sets the ASCII code for the carriage return character.
S4 decimal 0–127 10 (^J) Sets the ASCII code for the line feed character.
S5 decimal 0–32 8 (^H) Sets the ASCII code for the backspace character.

33–127 Values greater than 32 disable backspace.
S6 seconds 2–65* 2* Sets the time the modem waits after it goes off-hook before it

begins to dial the telephone number.

S7 seconds 35-65* 50* Sets the time the modem waits for a carrier signal before

aborting a call. Also sets the wait for silence time for the @ dial
modifier.

S8 seconds 0–65 2 Sets the length of a pause caused by a comm a character in a

dialing command.

S9 decimal 0, 1–127 37 (%) Sets ASCII code for remote configuration escape character.

S9=0 disables remote configuration.

S10 100 ms 1–254 20 Sets how long a carrier signal must be lost before the modem

disconnects.

S11 1 ms 50–150* 95* Sets spacing and duration of dialing tones.
S28 decimal 0, 1–255 1 0 disables, 1–255 enables V.34 modulation.
S30 1 minute 0, 1–255 0 Sets the length of time that the modem waits before

disconnecting when no data is sent or received. A value of
zero disables the timer. See also the \T command

S35 decimal 0–1 1 0 disables, 1 enables the V.25 calling tone, which allows

remote data/fax/voice discrimination.

S36 decimal 0–7 7 Specifies the action to take in the event of a negotiation failure

when error control is selected. (See S48.)

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Chapter 1 – AT Commands, S-Registers and Result Codes

S37 decimal 0–19 0 Sets the maximum V.34 “upstream” speed at which the

modem attempts to connect.
0 = maximum speed
1 = reserved
2 = 1200/75 bps
3 = 300 bps
4 = reserved

5 = 1200 bps

6 = 2400 bps

7 = 4800 bps

8 = 7200 bps

9 = 9600 bps

10 = 12000 bps

11 = 14400 bps

12 = 16800 bps

13 = 19200 bps

14 = 21600 bps

15 = 24000 bps

16 = 26400 bps

17 = 28800 bps

18 = 31200 bps

19 = 33600 bps
S38 decimal 0–23 1 Sets “downstream” data rate where V.90 provid es rates of

28,000 to 56,000 bps in increments of 1,333 bps.
0 = V.90 disabled

1 = V.90 auto rate

2 = 28,000 bps

3 = 29,333 bps

4 = 30,666 bps

5 = 32,000 bps

6 = 33,333 bps

7 = 34,666 bps

8 = 36,000 bps

9 = 37,333 bps

10 = 38,666 bps

11 = 40,000 bps

12 = 41,333 bps

13 = 42,666 bps

14 = 44,000 bps

15 = 45,333 bps

16 = 46,666 bps

17 = 48,000 bps

18 = 49,333 bps

19 = 50,666 bps

20 = 52,000 bps

21 = 53,333 bps

22 = 54,666 bps

23 = 56,000 bps
Upstream data rates: Upstream V.90 data rates are 4800 to

33,600 bps in 2400 bps increments.
S43 decimal 0–1 1 For testing and debugging only. Enables/disables V.32bis

start-up auto mode operation. 0 = disable; 1 = enable.

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 29

Chapter 1 – AT Commands, S-Registers and Result Codes

S48 decimal 7 or 128 7 Enables (7) or disables (128) LAPM negotiation. The following

table lists the S36 and S48 configuration settings for certain

types of connections.

S48=7 S48=128

S36=0, 2 LAPM or hang up Do not use
S36=1, 3 LAPM or async Async
S36=4, 6 LAPM, MNP, or hang up MNP or hang up
S36=5, 7 LAPM, MNP, or async MNP or async

S89 seconds 0, 5–255 10 Sets the length of time in the off-line command mode before

the modem goes into standby mode or “sleep mode”. A value

of zero prevents standby mode; a value of 1–4 sets the value

to 5. Standby mode (sleep mode or low power mode) is

controlled by S89. It programs the number of seconds of

inactivity before the modem will go to sleep. The default value

is 0. A value of 0 disables standby mode. The modem will

wake on an incoming ring or an AT command.
S108 decimal 0–3, 6, 7 6 Selects the 56K digital loss if using the modem through a PBX

line. The default value is -6 dB loss, the value used when

calling from a typical POTS line long distance.
0 = -0 dB digital loss, no robbed-bit signaling

1 = -3 dB PBX digital loss

2 = -2 dB digital loss

3 = -3 dB digital loss

6 = -6 dB digital loss

7 = -0 dB digital loss with robbed-bit signaling

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 30