Multitech SocketModem MT5600SMI, SocketModem MT5656SMI Reference Manual

SocketModem



SocketModem

SocketModem

AT Commands

MT5600SMI



MT5656SMI

Fax Commands

Voice Commands

Reference Guide

Copyright and Technical Support

SocketModem Reference Guide

MT5600SMI and MT5656SMI
S000306C, Rev. C

Copyright

This publication may not be reproduced, in whole or in part, without prior expressed written permission
from Multi-Tech Systems, Inc. All rights reserved.
Copyright © 2002-2006, by Multi-Tech Systems, Inc.

Multi-Tech Systems, Inc. makes no representations 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 09/04/03 First release.
B 06/04/04 Created a separate Universal Socket Hardware guide and a separate AT

Command Reference Guide.

C 01/12/06 Added a chapter that covers setting country/regional codes. Clarified the

default for Command B and S-Register S27 (bit 6).

Patents

This device covered by one or more of the following patents: 6,219,708; 6,031,867; 6,012,113; 6,009,082;
5,905,794; 5,864,560; 5,815,567; 5,815,503; 5,812,534; 5,809,068; 5,790,532; 5,764,628; 5,764,627;
5,754,589; 5,724,356; 5,673,268; 5,673,257; 5,644,594; 5,628,030; 5,619,508; 5,617,423; 5,600,649;
5,592,586; 5,577,041; 5,574,725; 5,559,793; 5,546,448; 5,546,395; 5,535,204; 5,500,859; 5,471,470;
5,463,616; 5,453,986; 5,452,289; 5,450,425; 5,355,365; 5,309,562; 5,301,274
Other Patents Pending.

Trademarks

Registered Trademarks of Multi-Tech Systems, Inc. are SocketModem and the Multi-Tech logo.
Microsoft and Windows are registered trademarks or trademarks of Microsoft Corporation in the United
States and/or other countries. All other trademarks are owned by their respective companies.

World Headquarters

Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 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 MT5600SMI/MT5656SMI Reference Guide (S000306C) 2

Table of Contents

Contents

Chapter 1 – AT Commands, S-Registers and Result Codes....................................................................4

Introduction................................................................................................................................................ 4

Escape Code Sequence – +++ .................................................................................................................4

Data Commands........................................................................................................................................ 5

Generic Modem Control Commands ..................................................................................................... 5

DTE-Modem Interface Commands.......................................................................................................... 11

Call Control Commands .......................................................................................................................... 16

Modulation Control Commands...............................................................................................................26

Error Control Commands......................................................................................................................... 30

Data Compression Commands ...............................................................................................................35

V.8/V.8bis Commands.............................................................................................................................38

Diagnostic Commands ............................................................................................................................ 40

Example Modem Response and Usage .............................................................................................. 44

Compatibility Commands......................................................................................................................... 45

Fast Connect Commands........................................................................................................................46

V.92 +P and –Q Commands ...................................................................................................................47

S-Registers.............................................................................................................................................. 51

Result Codes ........................................................................................................................................... 59

Chapter 2 – Fax Class 1 Commands.........................................................................................................62

Fax I/O Processing .................................................................................................................................. 62

DTE-to-Modem Transmit Data Stream ................................................................................................ 62

Modem-to-DTE Receive Data Stream.................................................................................................62

Fax Mode Selection ............................................................................................................................. 63

Fax Origination..................................................................................................................................... 63

Fax Answering .....................................................................................................................................63

Fax Control Transmission .................................................................................................................... 63

Fax Control Reception .........................................................................................................................64

Fax Data Transmission ........................................................................................................................ 65

Fax Data Reception .............................................................................................................................65

Commands and Parameters ................................................................................................................... 66

Mode Entry Commands ....................................................................................................................... 66

Mode Commands................................................................................................................................. 66

Service Class 1 Commands .................................................................................................................... 70

Examples................................................................................................................................................. 74

Chapter 3 – Fax Class 2 Commands.........................................................................................................76

Command and Syntax Guidelines...........................................................................................................77

Mode Entry Commands ....................................................................................................................... 77

DTE Commands ..................................................................................................................................77

Serial Port Speed and Flow Control ....................................................................................................78

Auto Answer......................................................................................................................................... 79

Identification of T.30 Options ............................................................................................................... 79

Session Status Reporting ....................................................................................................................79

Procedure Interrupt Negotiation........................................................................................................... 79

Service Class 2 Identification and Selection ........................................................................................... 80

Service Class 2 Action Commands ......................................................................................................... 81

Service Class 2 DCE Responses............................................................................................................ 88

Service Class 2 Parameters .................................................................................................................... 91

Example Sessions ................................................................................................................................... 95

Chapter 4 – Voice Commands...................................................................................................................97

Voice Commands Overview .................................................................................................................... 97

<DLE> Shielded Event Codes Sent to the DTE .................................................................................. 98

<DLE> Shielded Codes Sent to the Modem (DCE)............................................................................. 99

Voice Configuration Commands............................................................................................................ 100

Basic Voice Commands ........................................................................................................................101

Chapter 5 – Setting Country or Regional Codes...................................................................................112

Index...........................................................................................................................................................113

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 3

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 com mand 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 command, e.g., +++ 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 autoanswer 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 (depending on the terminal program it could be some other key) 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 messages that the

modem sends to the computer when it is connecting to another modem. See “Result Codes” at the end of
this chapter for a table of valid result codes.

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.

Escape Code Sequence – +++

When the modem has established a connection and has entered online data mode, it is possible to break
into the data transmission in order to issue further commands to the modem in an online command mode.
This is achieved by the DTE sending to the modem a sequence of three ASCII characters specified by S­Register S2. The default character is '+'. The maximum time allowed between receipt of the last character
of the three-escape character sequence from the DTE and sending of the OK result code to the DTE is
controlled by the S12 register.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 4

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

Data Commands

The modem will respond to the commands detailed below. Parameters applicable to each command are
listed with the command description.

Generic Modem Control Commands

Command: Z Soft Reset and Restore Profile

Description: Causes the modem to perform a soft reset and restore (recall) the

configuration profile. If no value is specified, zero is assumed.
Default: None
Values: Number corresponding to the selected profile:
Z0 Soft reset and restore stored profile 0.
Z1 Soft reset and restores stored profile 1.
Result Codes: OK
Otherwise ERROR

Command: +FCLASS Select Active Service Class

Description: Selects the active service class (mode).
Default: 0
Defined Values: +FCLASS=0 Select Data Mode (Default).
+FCLASS=1 Select Facsimile Class 1 Mode.
+FCLASS=1.0 Select Facsimile Class 1.0 Mode.
+FCLASS =2 Fax Service Class 2
+FCLASS=2.0 Fax Service Class 2.0
+FCLASS=2.1 Fax Service Class 2.1
+FCLASS=8 Select Voice Mode.
+FCLASS=10 Reserved.

Note: Fax Class 2 and Voice Mode apply to MT5656SMI only

Result Codes: OK
Otherwise ERROR
Report Commands: +FCLASS? Reports Current or Selected Values

+FCLASS=? Reports Range of Parameters

Command: +VCID Caller ID (CID)

Description: Controls the reporting and presentation of data associated with the Caller

Default: 0
Defined Values: +VCID0 Disable Caller ID reporting.
+VCID1 Enables Caller ID with formatted presentation to the DTE. The

+VCID2 Enables Caller ID with unformatted presentation to the DTE.

Report Commands: +VCID?

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 5

+VCID=? Reports Range of Parameters

ID services in the Incoming Call Line ID (ICLID) data format for the next

call. (U.S. only)

modem presents the data items in a <Tag><Value> pair
format. The expected pairs are date, time, name, and caller
code (telephone number).

Reports the Mode

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

Command: +VRID Report Retrieved Caller ID (CID)

Description: Reports the data associated with the Caller ID services in the Incoming

Caller Line (ICLID) data format for the last received call. U.S. only
Default: None
Defined Values: +VRID0 Reports Caller ID with formatted presentation to the DTE. The

modem presents the data items in a <Tag><Value> pair
format. The expected pairs are date, time, name, and caller
code (telephone number).

+VRID1 Reports Caller ID with unformatted presentation to the DTE.

Report Commands: +VRID?

Reports the Mode

Command: \N Operating Mode - Error Correction

Description: Controls the preferred error-correcting mode to be negotiated in a

subsequent data connection. This command is affected by the OEM

firmware configuration.
Default: 5
Defined Values: \N0 Selects normal speed buffered mode (disables error-correction

mode). (Forces &Q6.)

\N1 Serial interface selected: Selects direct mode and is equivalent to

&M0, Q0 mode of operation. (Forces &Q0.) Parallel interface
selected: Same as \N0.

\N2 Selects reliable (error-correction) mode. The modem will first attempt

a LAPM connection and then an MNP connection. Failure to make a
reliable connection results in the modem hanging up. (Forces &Q5,
S36=4, and S48=7.)

\N3 Selects auto-reliable mode. This operates the same as \N2 except

failure to make a reliable connection results in the modem falling
back to the speed buffered normal mode. (Forces &Q5, S36=7, and
S48=7.)

\N4 Selects LAPM error-correction mode. Failure to make an LAPM

error-correction connection results in the modem hanging up.

(Forces &Q5 and S48=0.) Note: The -K1 command can override the

\N4 command.

\N5 Selects MNP error-correction mode. Failure to make an MNP error-

correction connection results in the modem hanging up. (Forces

&Q5, S36=4, and S48=128.)
Result Codes: OK
Otherwise ERROR

Command I Identification

Description: Causes the modem to reports the requested result according to the

command parameter.
Default: None
Defined Values: I0 Reports product code (e.g., 56000).
I1 Reports the least significant byte of the stored checksum (e.g.,

12AB).

I2 Checks ROM and verifies the checksum. Reports OK or ERROR.
I3 Reports ROM Code Revision-Modulation (e.g., 2109-V90).
I4 Reports OEM defined identifier string in binary format (default) or

ASCII formats. (e.g.: a007040284C6002F bC60000000

r1005111151012000 3000111170000000).
I5 Reports Country Code parameter (see +GCI).
I6 Reports modem data pump model and internal code revision.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 6

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

Command: +GMI Request Manufacturer Identification

Description: Causes the modem to report the modem product manufacturer.
Typical Response: +GMI: Multi-Tech
OK

Command +GMM Request Model Identification

Description: Causes the modem to report the modem product.
Typical Response: +GMM: V92

Command: +GMR Request Revision Identification

Description: Causes the modem to report the modem version, revision level, or date.

This is the same as the I3 command.
Typical Response: +GMR: P2109-V90
OK

Command: +GCAP Request Complete Capabilities List

Description: This extended-format command causes the modem to transmit one or

more lines of information text listing additional capabilities command

+<name>s, which is intended to permit the user to identify the overall

capabilities of the modem. In particular, if the modem implements a

particular modem control standard that uses Extended Syntax Commands,

and if that modem control standard includes command(s) that indicate

general capabilities, the +<names>(s) of those commands will be reported

to the modem in response to a +GCAP command.
Example Responses: +GCAP: +FCLASS, +MS, +ES, +DS, for a data modem that supports all

capabilities listed. Where:
+MS +M commands (Modulation Control: +MS and +MR commands)
+ES +E commands (Error Control: +ES, +EB, +ER, +EFCS, +ETBM)
+DS +D commands (Data Compression: +DS and +DR). Manual

Command: +GCI Country/Region of Installation

Description: This extended syntax command selects and indicates the country or region

of installation for the modem. This parameter selects the settings for any

operational parameters that need to be adjusted for national regulations or

telephone networks. The chapter Setting Country Codes for more

information.
Default: If the modem is specified for use in only one country, that country code is

the default. Otherwise, the default is defined by the OEM. Factory default is

B5 (United States).
Report Commands: +GCI? Reports the current country code.
+GCI=? Displays the list of available country codes.

Command: &F Restore Factory Configuration (Profile)

Description: The modem loads the factory default configuration (profile). The factory

defaults are identified for each command and in the S-Parameter

descriptions. A configuration (profile) consists of a subset of S-Parameters.
Default: None
Values: &F0 Restore factory configuration 0.
&F1 Restore factory configuration 1.
Result Codes: OK
ERROR if the modem is connected.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 7

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

Command: &T Local Analog Loopback Test

Description: The modem will perform the local analog loopback test if &T1 is selected.

The test can be run only when in an asynchronous operation in non-error-

correction mode (normal), e.g., AT&Q6. To terminate the test in progress,

the escape sequence must be entered first.
Default: None
Defined Values: &T0 Terminates test in progress. Clears S16.
&T1 Initiates local analog loopback, V.54 Loop 3. Sets S16 bit 0. If a

connection exists when this command is issued, the modem hangs
up. The CONNECT XXXX message is displayed upon the start of
the test.

Command: &Y Designate a Default Reset Profile

Description: Selects which user profile will be used after a hard reset.
Default: None
Defined Values: &Y0 The modem will use profile 0.
&Y1 The modem will use profile 1.
Result Codes: OK
ERROR if <value> > is1 or if NVRAM is not installed or is not operational.

Command: &W Store Current Configuration

Description: Saves the current (active) configuration (profile), including S-Parameters,

in one of the two user profiles in NVRAM as denoted by the parameter

value. This command will yield an ERROR message if the NVRAM is not

installed or is not operational as detected by the NVRAM test.
The current configuration is comprised of a list of storable parameters

illustrated in the &V command. These settings are restored to the active

configuration upon receiving a Z command or at power up (see &Y

command).
Default: 0
Defined Values: &W0 Store the current configuration as profile 0.
&W1 Store the current configuration as profile 1.
Result Codes: OK
Otherwise ERROR

Command &Zn=x Store Telephone Number

Description: The modem can store up to four telephone numbers and each telephone

number dial string can contain up to 31 digits. (Requires 256-byte NVRAM

installed.)
Default: None
Defined Values: <string> Dial string from 0 to 31 characters.
Result Codes: OK For <value> =3, and <string> =31 digits.
ERROR If <value> > 3, <string> > 31 digits, or if NVRAM is not installed or

is not operational.

Command %7 Plug and Play Serial Number

Description: Sets and stores eight serial numbers in hex format used for serial Plug and

Play and for ISA Plug and Play which use the Conexant 11596 Plug and

Play device. Applicable to Desktop configuration only.
Example: %7<8 hex numbers><same 8 hex numbers>
Result Codes: OK <8 hex numbers><same 8 hex numbers>
Otherwise ERROR
Report Command: AT"? Reports the stored serial number, issue.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 8

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

Command %8 Plug and Play Vendor ID and Product Number

Description: Sets and stores Vendor ID and product number for serial Plug and Play

and for ISA Plug and Play which use the Conexant 11596 Plug and Play

device. Applicable to Desktop configuration only.
Default: None
Example: %8<3 ASCII characters><4 hex numbers><same 3 ASCII

characters><same 4 hex numbers><cr>
Result Codes: OK <3 ASCII characters><4 hex numbers><same 3 ASCII

characters><same 4 hex numbers>
Otherwise ERROR

Command ** Load Flash Memory

Description: The linear flash memory uploader allows flash memory connected to the

modem external memory bus to be upgraded with revised modem

firmware. This process transfers (uploads) the upgraded modem firmware

(data) from the host computer to the modem which transfers the data to the

flash memory device. The linear flash memory downloader allows the flash

memory connected to the modem external memory bus to read and saved.

This process transfers (downloads) the current modem firmware (data) to

the host computer. Uploading new firmware to the flash memory or

downloading existing firmware from the flash memory device is a two-step

process.

1. When the AT** command is issued, the modem firmware boot loader is

invoked and the user will first load a flash load module (FLM) into the
modem's RAM. If the user wishes to upload new firmware to the
modem, he should load the uploader FLM. If the user wishes to
download existing firmware from the modem, he should load the
downloader FLM. In either case, the data transfer is done via an ASCII
transfer. The FLM contains the programming algorithm for the flash
memory device being programmed and any messages that may be sent
during the load process.

2. If the user wishes to upload new firmware to the modem, then he will

then load the new modem firmware, which the uploader FLM will then
program into the flash memory device. This transfer is done via
XMODEM transfer. If the user wishes to download existing firmware
from the modem, then he will set up the host PC for XMODEM receive
and the downloader FLM will begin to send the existing firmware from
the flash memory to the host PC.

Procedure

1. Install in the modem a flash memory programmed with the modem

firmware or a blank flash memory.

2. Put the uploader FLM and downloader FLM files and the new modem

firmware file (e.g., XmUL003.s37, XmDL003.s37, and 206s4712.S37)
in an appropriate directory on the computer's hard disk.

3. Configure the communications application program for a DTE rate of

between 9600 bps and 115200 bps and RTS/CTS flow control.

4. Check the modem for response by typing AT.

5. Initiate the download process using the AT** command. The

"Download flash code…" message appears upon issuing the AT**
command.

6. Perform an ASCII transfer of the FLM file (e.g., XmUL003.s37 for

uploading new firmware to the modem or XmDL003.s37 for
downloading existing firmware from the modem) from the host
computer to the modem RAM using an industry standard
communications software or an equivalent process (ensure that all
ASCII translation or pacing is turned off).

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 9

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

7. After the FLM has been loaded, if uploading new firmware to the

modem, perform an XMODEM upload of the new modem firmware hex
file (e.g., 206s4712.S37) from the host computer to the modem RAM
using industry standard communications software or an equivalent
process. If downloading existing firmware from the modem, using an
industry standard communications software or equivalent, put the host
PC in XMODEM receive mode.

8. The messages described in Table 1-1 may occur during the uploading

process:

Table 1-1. Upload Messages

Message Description

Device not supported Displayed if the FLM used does not support the flash

memory that is installed on the board.

Wrong S37 format Displayed if the modem firmware being uploaded is not in

Motorola S3 format.

Record error Displayed if there is an error while either uploading or

downloading. If this occurs, the transfer should be aborted,
and the user should restart at step .5

Download abort Displayed if the transfer is aborted before it is finished. If this

occurs, the user should restart at step 5.

Erase fail Displayed if the FLM is unable to erase the flash memory. If

this occurs, the user should restart at step 5.
Download error, Re­Load

Displayed if there was an error when uploading or

downloading. If this occurs, the user should restart at step 5.
Error, No H/W flow ctl Displayed if RTS-CTS flow control is not set. If this occurs,

the user should restart at step 3.
DTE timeout Displayed if the DTE has stopped the XMODEM transfer

process before it is finished. If this occurs, the user should

restart at step 5.
Code doesn’t match
Hardware

Displayed if the user is attempting to upload a firmware that

either not the same model (parallel, serial, etc.), crystal

frequency, or size (1Mbit, 2Mbit, etc.) as the firmware that is

currently on the board. If this occurs, the FLM will abort and

not allow the user to continue.
Device successfully
Programmed

Displayed by the FLM at the completion of a successful

upload or download then the modem will do a cold start.

The uploader and downloader flash load modules (FLM) have several built in safety

mechanisms to reduce the risk of a failed flash upload/download. The FLM will not allow
a user to upload a firmware of different model (serial, parallel, etc.) or crystal speed than
what is currently in the flash memory. Also, it will not allow the user to upload a firmware
that is larger in size than the flash memory itself (e.g., a 2Mbit firmware onto a 1Mbit flash
memory). It will, however, allow the user to upload a firmware that is smaller in size than
the flash memory, and it will program the firmware with the appropriate offset in order for
the firmware to function properly. In the instance that there is a failure during the
download or upload process, the modem will be in a “flash rescue mode”. In this mode,
the modem will respond “OK” to all AT commands, but will only take action on the AT**
command, so a new attempt to upload or download can be initiated. When the modem is
in the “flash rescue mode” it will only be able to respond to AT commands if the DTE rate
has not been changed since the last AT** command was successfully issued, even if the
modem is powered off and on.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 10

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

DTE-Modem Interface Commands

The parameters defined in this section control the operation of the interface between the DTE and
modem.

Command: E Command Echo

Description: The modem enables or disables the echo of characters to the DTE. The

parameter value, if valid, is written to S14 bit 1.
Default: 1
Defined Values: E0 Disables command echo.
E1 Enables command echo.
Result Codes: OK
Otherwise ERROR

Command: Q Quiet Result Code Control

Description: Enables or disables the sending of result codes to the DTE. The parameter

value, if valid, is written to S14 bit 2.
Default: 0
Defined Values: Q0 Enables result codes to the DTE.
Q1 Disables result codes to the DTE.
Result Codes: OK
Otherwise ERROR

Command: V Result Code Form

Description: Selects the sending of short-form or long-form result codes to the DTE.

The parameter, if valid, is written to S14 bit 3.
Default: 1
Defined Values: V0 Enables short-form (terse) result codes. Line feed is not issued

before a short-form result code.
V1 Enables long-form (verbose) result codes.
Result Codes: OK
Otherwise ERROR

Command: W Connect Message Control

Description: This command, in conjunction with S95 bits 0, 2, 3, and 5 (bits 2, 3, and 5

can be written directly by the host or by the +MR, +ER, and +DR
commands, respectively), control the format of CONNECT messages. The
actual result code messages reported reflect the W command setting and
the S95 bit settings. (Also see +MR, +ER, and +DR commands.) The W

parameter value, if valid, is written to S31 bits 2 and 3.
Default: 0
Defined Values: W0 Upon connection, the modem reports only the DTE speed (e.g.,

CONNECT 19200). Subsequent responses are disabled.

W1 Upon connection, the modem reports the modulation, line speed, the

error correction protocol, and the DTE speed, respectively.
Subsequent responses are disabled.

W2 Upon connection, the modem reports the DCE speed (e.g.,

CONNECT 14400). Subsequent responses are disabled.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 11

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

Command: X Extended Result Codes

Description: Selects the subset of the result code messages used by the modem to

inform the DTE of the results of commands. Blind dialing is enabled or
disabled by country parameters. If the user wishes to enforce dial tone
detection, a "W" can be placed in the dial string (see D command). The
information below is based upon the default implementation of the X results
table.

If the modem is in facsimile mode (+FCLASS=1, 1.0, or 2), the only

message sent to indicate a connection is CONNECT without a speed

indication. See the table of Result Codes at the end of this chapter.
Default: 4
Defined Values: X0 Disables reporting of busy tones unless forced otherwise by country

requirements; send only OK, CONNECT, RING, NO CARRIER,
ERROR, and NO ANSWER result codes. Blind dialing is
enabled/disabled by country parameters. If busy tone detection is
enforced and busy tone is detected, NO CARRIER will be reported. If
dial tone detection is enforced or selected and dial tone is not
detected, NO CARRIER will be reported instead of NO DIAL TONE.
The value 000b is written to S22 bits 6, 5, and 4, respectively.

X1 Disables reporting of busy tones unless forced otherwise by country

requirements; send only OK, CONNECT, RING, NO CARRIER,
ERROR, NO ANSWER, and CONNECT XXXX (XXXX = rate). Blind
dialing enabled/disabled by country parameters. If busy tone
detection is enforced and busy tone is detected, NO CARRIER will
be reported instead of BUSY. If dial tone detection is enforced or
selected and dial tone is not detected, NO CARRIER will be reported
instead of NO DIAL TONE. The value 100b is written to S22 bits 6, 5,
and 4, respectively.

X2 Disables reporting of busy tones unless forced otherwise by country

requirements; send only OK, CONNECT, RING, NO CARRIER,
ERROR, NO DIAL TONE, NO ANSWER, and CONNECT XXXX. If
busy tone detection is enforced and busy tone is detected, NO
CARRIER will be reported instead of BUSY. If dial tone detection is
enforced or selected and dial tone is not detected, NO DIAL TONE
will be reported instead of NO CARRIER. The value 01b is written to
S22 bits 6, 5, and 4, respectively.

X3 Enables reporting of busy tones; send only OK, CONNECT, RING,

NO CARRIER, ERROR, NO ANSWER, and CONNECT XXXX. Blind
dialing is enabled/disabled by country parameters. If dial tone
detection is enforced and dial tone is not detected, NO CARRIER will
be reported. The value 110b is written to S22 bits 6, 5, and 4,
respectively.

X4 Enables reporting of busy tones; send all messages. The value 111b

is written to S22 bits 6, 5, and 4, respectively.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 12

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

Command: &C RLSD (DCD) Option

Description: The modem controls the RLSD output in accordance with the parameter

supplied. The parameter value, if valid, is written to S21 bit 5.
Default: 1
Defined Values: &C0 RLSD remains ON at all times.
&C1 RLSD follows the state of the carrier.
Result Codes: OK
Otherwise ERROR

Command: &D DTR (Data Terminal Ready) Option

Description: Interprets the ON to OFF transition of the DTR signal from the DTE in

accordance with the parameter supplied. The parameter value, if valid, is

written to S21 bits 3 and 4. Also, see S25.
Default: 2
Defined Values: &D0 DTR drop is interpreted according to the current &Q setting as

follows:

&Q0, &Q5, &Q6: DTR is ignored (assumed ON). Allows operation

with DTEs, which do not provide DTR.

Q1 DTR drop causes the modem to hang up. Auto-answer is not

affected.

&Q2, &Q3 DTR drop causes the modem to hang up. Auto-answer is

inhibited.

&D1 DTR drop is interpreted according to the current &Q setting as

follows:

&Q0, &Q1, &Q5, &Q6 DTR drop is interpreted by the modem as if

the asynchronous escape sequence had been entered. The modem
returns to asynchronous Command State without disconnecting.

&Q2, &Q3 DTR causes the modem to hang up Auto-answer is

inhibited.

&D2 DTR drop is interpreted according to the current &Q setting as

follows:

&Q0 through &Q6 drop caused the modem to hang up. Auto-answer

is inhibited.

&D3 DTR drop is interpreted according to the current &Q setting as

follows:

&Q0, &Q1, &Q5, &Q6 DTR drop causes the modem to perform a soft

reset as if the Z command were received. The &Y setting determines
which profile is loaded.

&Q2, &Q3 DTR drop causes the modem to hang up. Auto-answer is

inhibited.

If &Q5, &Q6, +FCLASS=1 or +FCLASS=2 is in effect, the action

taken is the same as for &Q0.

Command: &K Flow Control

Description: Defines the DTE/DCE (terminal/modem) flow control mechanism. The

parameter value, if valid, is written to S39 bits 0, 1, and 2.
Default: 3 (for data modem modes)
Defined Values: 0 Disables flow control.
3 Enables RTS/CTS flow control.
4 Enables XON/XOFF flow control.
5 Enables transparent XON/XOFF flow control.

Note: Upon reset, both RTS/CTS and XON/XOFF flow control is enabled

for fax modem and voice modes.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 13

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

Command: &R RTS/CTS (Request to Send/Clear to Send) Option

Description: This selects how the modem controls CTS. CTS operation is modified if

hardware flow control is selected (see &K command). The parameter

value, if valid, is written to S21 bit 2.
Default: None
Defined Values: &R0 In sync mode, CTS tracks the state of RTS; the RTS-to-CTS delay is

defined by S26. In async mode, CTS is normally ON and will turn
OFF only if required by flow control.

&R1 In sync mode, CTS is always ON (RTS transitions are ignored).

Tracks the state of RTS; In async mode, CTS is normally ON and will

turn OFF only if required by flow control.
Result Codes: OK
Otherwise ERROR

Command: &S DSR (Data Set Ready) Override

Description: Selects how the modem will control DSR. The parameter value, if valid, is

written to S21 bit 6.
Default: 0
Defined Values: &S0 DSR will remain ON at all times.
&S1 DSR will become active after answer tone has been detected and

inactive after the carrier has been lost.
Result Codes: OK
Otherwise ERROR

Command: +IPR Fixed DTE (Data Terminal Equipment) Rate

Description: This numeric extended-format parameter specifies the data rate at which

the modem will accept commands during online operation. It may be used
to select operation at rates at which the modem is not capable of
automatically detecting the data rate being used by the DTE. Specifying a
value of 0 disables the function and allows operation only at rates
automatically detectable by the modem. The specified rate takes effect
following the issuance of any result code(s) associated with the current
command line.

The <rate> specified does not apply in Online Data State if Normal Mode

(Direct Mode) of operation is selected.
Default: None
Defined Values: <rate> Specifies the DTE-modem interface operation rate in bits/s.
The available rates are 0, 300, 1200, 2400, 4800, 9600, 19200, 38400,

57600, 115200, or 230400.
If unspecified or set to 0, automatic detection is selected and the character

format is also forced to autodetect, +ICF=0.
If the rate specified is not supported by the modem, an ERROR result code

will be returned.
Report Commands: +IPR? Reports current rates

+IPR=? Reports current range Example: +IPR:

(0,300,1200,2400,4800,9600,19200,38400,57600,115200, 230400)

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 14

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

Command: +IFC DTE-Modem Local Flow Control

Description: This extended-format compound parameter controls the operation of local

flow control between the DTE and the modem during the data state when

V.42 error control is used, or when fallback to non-error control mode is

specified to include buffering and flow control.
It accepts two numeric subparameters.
Default: 2

Defined Values: Values defined by <modem_by_DTE> Specifies the method to be used

by the DTE to control the flow of received data from the modem.
+IFC0 None
+IFC1 XON/XOFF on transmitted data (XON/XOFF on transmit data);

do not pass XON/XOFF characters to the remote modem.
+IFC2 Circuit 133 (Ready for Receiving).
+IFC3 DC1/DC3 on circuit 103 (Transmitted Data) with DC1/DC3

characters being passed through to the remote DCE in addition

to being acted upon for local flow control.

Values defined by

by the modem to control the flow of transmitted data from the DTE.
+IFC0 None.
+IFC1 XON/XOFF on received data.
+IFC2 CTS/RTS.
Report Commands: +IFC? Reports the current or selected values
Response: +IFC: <modem_by_DTE>,<DTE_by_modem>
Example: +IFC: 2,2 For the defaults.
+IFC=? Reports the supported range of parameter values
R esponse: +IFC: (<modem_by_DTE> range),(<DTE_by_modem> range)
Example: +IFC: (0-3),(0-2).

<DTE_by_modem> Specifies the method to be used

Command: +ILRR DTE-Modem Local Rate Reporting

Description: This extended-format numeric parameter controls whether or not the

extended-format +ILRR:<rate> information text is transmitted from the

modem to the DTE.
Default: 0
Defined Values: +ILRR0 Disables reporting of local port rate (+ILRR: is not transmitted).
+ILRR1 Enables reporting of local port rate (+ILRR: is transmitted).
Report Commands: +ILRR? Reports current value
+ILRR=? Reports supported range of parameter values
Reported Rate: The <rate> reported represents the current (negotiated or renegotiated)

DTE-modem rate. If enabled, the intermediate result code is transmitted

after any modulation, error control or data compression reports are

transmitted, and before any final result code (e.g., CONNECT) is

transmitted. The <rate> is applied after the final result code is transmitted.
The DTE-modem port rate will change only if neither buffered mode nor

error controlled means are enabled (+ES=x,0) and if the negotiated carrier

rate (+MRR) does not match the current DTE-modem port rate

(autodetected from the previous command line).

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 15

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

Call Control Commands

Command: D Dial

Description: Directs the modem to go on-line, dial according to the string entered and

attempt to establish a connection. If no dial string is supplied, the modem

will go on-line and attempt the handshake in originate mode.

Note: If the ATD command is issued before the S1 register has cleared,

the modem will respond with the NO CARRIER result code.
If +FCLASS=0 is selected, the modem will behave as a data modem and

will attempt to connect to another data modem. The modem will have up to

the period of time specified by register S6 or S7 to wait for carrier and

complete the handshake. If this time expires before the modem can

complete the handshake, the modem will go on-hook with the NO

CARRIER response. This command will be aborted in progress upon

receipt of any DTE character before completion of the handshake.
If +FCLASS=1, 1.0, or 2 is selected, the modem will behave as a facsimile

modem and attempt to connect to a facsimile machine (or modem) by

entering the HDLC V.21 channel 2 receive state (as if +FRH=3 had been

issued). This command will be aborted upon receipt of any DTE character

if the modem has not finished dialing. In this case, the modem will go on-

hook and return to command mode after displaying the NO CARRIER

message. If the modem has finished dialing, it proceeds as if the +FRH=3

command has been issued. (Refer to the +FRH command to determine

how the modem behaves following this stage.)

Dial Modifiers

The valid dial string parameters are described below. Punctuation

characters may be used for clarity, with parentheses, hyphen, and spaces

being ignored.
Defined Values: Character string <string> corresponding to the selected option(s).
0-9 DTMF digits 0 to 9.
* The 'star' digit (tone dialing only).
# The 'gate' digit (tone dialing only).

A-D DTMF digits A, B, C, and D. Some countries may prohibit sending of

these digits during dialing.

L Re-dial last number: the modem will re-dial the last valid telephone

number. The L must be immediately after the D with all the following

characters ignored).

P Select pulse dialing: Pulse Dialing is used in the dialed numbers that

follow until a T command is encountered. Affects current and

subsequent dialing. Some countries prevent changing dialing modes
after the first digit is dialed.

T Select tone dialing: Tone Dialing is used in the dialed numbers that

follow until a P is encountered. Affects current and subsequent

dialing. Some countries prevent changing dialing modes after the

first digit is dialed.
R This command will be accepted, but not acted on.
S=n Dial the number stored in the directory (n = 0 to 3). (See &Z.)
! Flash: the modem will go on-hook for a time defined by the value of

S29. Country requirements may limit the time imposed.
W Wait for dial tone: the modem will wait for dial tone before dialing the

digits following "W". If dial tone is not detected within the time

specified by S7 (US) or S6 (W-class), the modem will abort the rest

of the sequence, return on-hook, and generate an error message.
@ Wait for silence: the modem will wait for at least 5 seconds of silence

in the call progress frequency band before continuing with the next

dial string parameter. If the modem does not detect these 5 seconds

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 16

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

of silence before the expiration of the call abort timer (S7), the

modem will terminate the call attempt with a NO ANSWER message.

If busy detection is enabled, the modem may terminate the call with

the BUSY result code. If answer tone arrives during execution of this

parameter, the modem handshakes.
& Wait for credit card dialing tone before continuing with the dial string.

If the tone is not detected within the time specified by S7 (US

models) or S6 (W-class models), the modem will abort the rest of the

sequence, return on-hook, and generate an error message.
, Dial pause: the modem will pause for a time specified by S8 before

dialing the digits following ",".
; Return to command state. Added to the end of a dial string, this

causes the modem to return to the command state after it processes

the portion of the dial string preceding the ";". This allows the user to

issue additional AT commands while remaining off-hook. The

additional AT commands may be placed in the original command line

following the ";" and/or may be entered on subsequent command

lines. The modem will enter call progress only after an additional dial

command is issued without the ";" terminator. Use "H" to abort the

dial in progress, and go back on-hook.
^ Toggles calling tone enable/disable: applicable to current dial

attempt only.
( ) Ignored: may be used to format the dial string.

- Ignored: may be used to format the dial string.
<space> Ignored: may be used to format the dial string.
<i> Invalid character: will be ignored.
> If enabled by country specific parameter, the modem will generate a

grounding pulse on the EARTH relay output.

Command: T Set Tone Dial Default

Description: Forces DTMF dialing until the next P dial modifier or P command is

received. The modem will set an S-Parameter bit to indicate that all
subsequent dialing should be conducted in tone mode. The DP command

will override this command. Clears S14 bit 5.
This command may not be permitted in some countries. (See P.)
Result Code: OK

Command: P Set Pulse Dial Default

Description: Forces pulse dialing until the next T dial modifier or T command is

received. Sets S14 bit 5.
As soon as a dial command is executed which explicitly specifies the

dialing mode for that particular call (e.g., ATDT...), this command is

overridden so that all future dialing will be tone dialed. (See T command.)
This command may not be permitted in some countries.
Result Code: OK

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 17

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

Command: A Answer

Description: The modem will go off-hook and attempt to answer an incoming call if

correct conditions are met. Upon successful completion of answer

handshake, the modem will go on-line in answer mode. This command

may be affected by the state of Line Current Sense, if enabled. (Most

countries do not require Line Current Sense.) Operation is also dependent

upon +FCLASS command and country-specific requirements.
If +FCLASS=0 is selected, the modem will enter the Connect state after

exchanging carrier with the remote modem. If no carrier is detected within

a period specified in register S7, the modem hangs up. Any character

entered during the connect sequence will abort the connection attempt.
If +FCLASS=1, 1.0, or 2 is selected, the modem will go off-hook in V.21

answer mode. It will generate the V.21 2100 Hz answer tone for 3 ± 0.5

seconds and, following a delay of 70 ms, will proceed as if the +FTH=3

command were issued. At any stage up to (but excluding) the +FTH=3

command state, any character will abort the communication. (See the

description of the +FTH command for details.)

Command: H Disconnect (Hang-Up)

Description: Initiates a hang up sequence. This command may not be available for

some countries due to PTT restrictions.
Default: None
Defined Values: H0 The modem will release the line if the modem is currently on-line,

and will terminate any test (AT&T) that is in progress. Country
specific, modulation specific, and error correction protocol specific
(S38) processing is handled outside of the H0 command.

H1 If on-hook, the modem will go off-hook and enter command mode.

For US models, the modem will remain off-hook. For global models,
the modem will return on-hook after a period of time determined by

S7.
Result Codes: OK
Otherwise ERROR

Command: O Return to Online Data Mode

Description: Determines how the modem will enter the online data mode. If in the online

command mode, the modem enters the online data mode with or without a
retrain. If in the off-line command mode (no connection), the modem

reports ERROR.
Default: None
Defined Values: O0 Enters on-line data mode without a retrain.
Handling is determined by the Call Establishment task. Generally, if

a connection exists, this command connects the DTE back to the
remote modem after an escape (+++).

O1 Enters on-line data mode with a retrain before returning to on-line

data mode.

O2 Fast retrain without speed change (used for diagnostic purpose

only).

O3 Renegotiate rate without speed change (used for diagnostic purpose

only.

O4 Renegotiate rate down one speed (used for diagnostic purpose

only).
O5 Renegotiate rate up one speed (used for diagnostic purpose only).
Result Codes: OK
Otherwise ERROR (or if not connected)

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 18

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

Command: L Speaker Volume

Description: Sets the speaker volume control. The parameter value, if valid, is written to

S22 bits 0 and 1.
Default: 1
Defined Values: L0 Low volume.
L1 Low volume. (Default.)
L2 Medium volume.
L3 High volume.
Result Codes: OK
Otherwise ERROR

Command: M Speaker Control

Description: Selects when the speaker will be on or off. The parameter value, if valid, is

written to S22 bits 2 and 3.
Default: 1
Defined Values: M0 Speaker is always off.
M1 Speaker is on during call establishment, but off when receiving

carrier. (Default.)
M2 Speaker is always on.
M3 Speaker is off when receiving carrier and during dialing, but on

during answering.
Result Codes: OK
Otherwise ERROR

Command: &G Select Guard Tone

Description: Causes the modem to generate the guard tone selected by this command

(DPSK modulation modes only). The parameter value, if valid, is written to

S23 bits 6 and 7.
This command may not be permitted in some countries.
Default: 0
Defined Values: &G0 Disables guard tone. (Default.)
&G1 Disables guard tone.
&G2 Selects 1800 Hz guard tone.
Result Codes: <value> = 0 to 2
Otherwise ERROR

Command: &P Select Pulse Dial Make/Break Ratio

Description: Determines the make/break ratio used during pulse dialing. The default is

country-dependent. The parameter value, if valid, is written to S28 bits 3

and 4.
Default: 0
Defined Values: &P0 Selects 39%-61% make/break ratio at 10 pulses per second.
&P1 Selects 33%-67% make/break ratio at 10 pulses per second.
&P2 Selects 39%-61% make/break ratio at 20 pulses per second.
&P3 Selects 33%-67% make/break ratio at 20 pulses per second.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 19

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

Command: &V Display Current Configuration and Stored Profiles

Description: Reports the current (active) configuration, the stored (user) profiles, and

the first four stored telephone numbers. The stored profiles and telephone

numbers are not displayed if the NVRAM is not installed or is not

operational as detected by the NVRAM test during reset processing.
Result Code: OK
Example: AT&V
ACTIVE PROFILE:
B1 E1 L1 M1 N0 QO T V1 W0 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q5
&R1 &S0 &T5 &X0
S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002
S07:050 S08:002 S09:006
S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007
S38:020 S46:138
S48:007 S95:000

STORED PROFILE 0:
B1 E1 L1 M1 N0 QO T V1 W0 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q5
&R1 &S0 &T5 &X0
S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014
S11:095 S12:050 S18:000
S36:007 S40:104 S41:195 S46:138 S95:000

STORED PROFILE 1:
B1 E1 L1 M1 N0 QO T V1 W0 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q5
&R1 &S0 &T5 &X0
S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014
S11:095 S12:050 S18:000
S36:007 S40:168 S41:195 S46:138 S95:000

TELEPHONE NUMBERS:
0 = 1 =
2 = 3 =
OK.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 20

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

Command: &V1 Display Last Connection Statistics

Description: Displays the last connection statistics in the following format (shown with

typical results):
TERMINATION REASON LOCAL REQUEST
LAST TX rate 26400 BPS
HIGHEST TX rate 26400 BPS
LAST RX rate. 49333 BPS
HIGHEST RX rate 49333 BPS
PROTOCOL LAPM
COMPRESSION V42Bis
Line QUALITY 038
Rx LEVEL 015
Highest Rx State 67
Highest TX State 67
EQM Sum 00B4
Min Distance 0000
RBS Pattern 00

Rate Drop 00

Digital Loss 2000

Local Rtrn Count 00

Remote Rtrn Count 00

Flex 9481814347C4

RBS Pattern: Shows which bits are being robbed in the least significant 6

bytes, e.g., 03 indicates 2 robbed bits in bit positions 0 and 1.

Digital Loss: Shows if a pad was encountered and if so, what was the digital

loss. 2000 means 0dB.

Flex: Shows V.8bis information as follows:

First byte: Octet 13 (second byte of manufacturer id, 94 = 56K)
Second byte: Octet 14 (Licensee code: 81 = Conexant)
Third byte: Octet 15 (manufacturer's product capabilities)
Fourth byte: Octet 16 (56K version number)

Fifth byte: Octet 17 (Conexant pump code version number)
Sixth byte: Octet 18 (x-law and controller version number)

Bit 6 Forced/Not forced A-Law/µ-Law

0 = Forced A-Law/µ-Law.
1 = Not forced A-Law/µ-Law.

Bit 5 Select A-Law or µ-Law

0 = Select A-Law.
1 = Select µ-Law.

Bit 4:0 Controller version

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 21

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

Command: \V Single Line Connect Message Enable

Description: Enables or disables the single-line connect message format as follows:
Default: None
Defined Values:

When single line connect messages are enabled, there are no CARRIER,

The single line connect message format is:
CONNECT <DTE

Where:

\V0 Connect messages are controlled by the command settings X, W,

and S95.

\V1 Connect messages are displayed in the single line format described

below subject to the command settings V (Verbose) and Q (Quiet). In
Non-Verbose mode (V0), single line connect messages are disabled
and a single numeric result code is generated for CONNECT DTE.

PROTOCOL (+ER:), or COMPRESSION (+DR:) messages apart from the

fields described below.

Speed>/<Modulation>/<Protocol>/<Compression>/<Line Speed>

DTE Speed = DTE speed, e.g., 57600.

Modulation = “V92” for V.92 modulation.

“V90” for V.90 modulation.

“K56” for 56K modulation.

“V34” for V.34 modulation.

“V32” for V.32 or V.32bis modulation.

Note: Modulation is omitted for all other modulations.

Protocol = “NONE” for no protocol.

“ALT” for Microcom Network Protocol.

“LAPM” for LAP-M protocol.

Compression = “V44” for V.44 compression.

“V42B” for V.42bis compression.

“ALT” for Microcom MNP5 compression.

Note: Compression is omitted if protocol is NONE.

Line Speed = Asymmetric rates are displayed as “/rate:TX/rate:RX”,

e.g., /1200 TX/75 RX.

Symmetric rates are displayed as a single DCE rate,

e.g., 14400.

Command: %L Report Line Signal Level

Description: Returns a value, which indicates the received signal level. The value

returned is a direct indication (DAA dependent) of the receive level at the

MDP, not at the telephone line connector. For example, 009 = -9 dBm, 043

= -43 dBm, and so on.
Result Codes: OK

Command: %Q Report Line Signal Quality

Description: Reports the line signal quality (DAA dependent). Returns the higher order

byte of the EQM value. Based on the EQM value, retrain or fallback/fall

forward may be initiated if enabled by %E1 or %E2.
Example: AT%Q
015
Result Codes: OK If connected.
ERROR If not connected, or connected in 300 bps, V.23, or fax modes.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 22

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

Command: –STE= Set Telephony Extension

Description: Enables/disables Line-In-Use, Extension Pickup, and Remote Hangup

detection features.

Note: Additional hardware may be required to support these features.

Defined Values: The <value> corresponds to the selected bit-mapped options. The bit fields

are defined as follows:

Bit 0 Line-In-Use detection enable/disable.

Bit 1 Extension Pickup detection enable/disable.

Bit 2 Remote Hangup detection enable/disable.

<value>
(Dec.)

Remote
Hangup

Extension
Pickup

Line-in-Use

0 (default) Disabled Disabled Disabled

1 Disabled Disabled Enabled
2 Disabled Enabled Disabled
3 Disabled Enabled Enabled
4 Enabled Disabled Disabled
5 Enabled Disabled Enabled
6 Enabled Enabled Disabled
7 Enabled Enabled Enabled

Report Commands: -STE? Reports current values
Example: -STE: 4 Remote Hangup enabled, Extension
Pickup disabled, and Line-In-Use disabled.

-STE=? Reports available options

Behavior in Data Mode (+FCLASS=0):

When on-hook, if the line is in use and an ATDT is issued, the modem will

not go off-hook and will return with the message LINE-IN-USE.
When off-hook and either an extension is picked up or a line reversal is

detected, the modem will drop the connection. The disconnect reason in

register S86=25 (this is also defined for #UD). The user must flash the

hook in order to get a dial tone due because the remote server will be

retraining.
If the local handset is picked up while the modem is off-hook, the modem

will do a link-disconnect, flash the hook for 1.5 seconds, and then connect

the local handset to the line. At this point, the user dial tone should be on

the local handset. The disconnect reason in S86=25.

Behavior in Voice Mode (+FCLASS=8):

When in voice mode and an extension is picked-up, a <DLE>P is sent to

In voice mode, there is no blocking of ATDT when the line is in use. Also,

Operation in Data Mode:
Line-In-Use

(Enabled by AT-STE=1, AT-STE=3, AT-STE=5, or AT-STE=7)
Case 1: Telephone Line is in Use

If an ATDT, ATDP or ATDL is issued while Line-In-Use detection is

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 23

the DTE. When the modem is off-hook, a line reversal may also be

detected in which case a <DLE>l is sent to the DTE.

there is no automatic hang-up in voice mode as in data mode. There is

only the above stated <DLE> shielding event reporting.

enabled and the telephone line is in use, the modem will immediately
return the message LINE-IN-USE to the DTE without going off-hook, and
then return to command mode.

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

Case 2: Telephone Line is in Use but Disconnected

If an ATDT, ATDP or ATDL is issued while Line-In-Use detection is

enabled and the telephone line is NOT in use, the modem will go off­hook after a short pause, then respond with CONNECT or NO CARRIER
message.

Case 3: Telephone Line is not Connected to Modem

If an ATDT, ATDP, or ATDL is issued while Line-In-Use detection is

enabled and the telephone line is not connected, the modem will go off­hook momentarily, go back on-hook, and then respond with NO DIAL
TONE message.

Extension Pick-up

(Enabled by AT-STE=2, AT-STE=3, AT-STE=6, or AT-STE=7):

Case 1: Modem off-hook, Local Handset Goes Off-Hook

If the local handset goes off-hook while the modem is in a data

connection, the local handset will be muted. The modem will then send a
GSTN Cleardown to the remote modem and then go on-hook. The
modem will then send a NO CARRIER message to the DTE. A result
code of 25 will be left in S86 register. After 2 seconds, the local handset
will be connected to the telephone line so the user hears the dial tone.

Remote Hang-up
(Enabled by AT-STE=4, AT-STE=5, AT-STE=6, or AT-STE=7):

Case 1: Modem off-hook, Remote Hang-up

If the modem is connected (off-hook) and the remote modem/server

goes hangs up, the central office may issue a line polarity reversal. If a
line polarity reversal is detected, the modem will drop the call and
respond with NO CARRIER. The reason for hang-up can be determined
by #UD or by S86=25. A line reversal can also be simulated by simply
pulling out the telephone line during a connection.

Operation in Voice Mode
Line-In-Use

(Enabled by AT-STE=1, AT-STE=3, AT-STE=5, or AT-STE=7):

This feature does not apply in voice mode.

Extension Pickup

(Enabled by AT-STE=2, AT-STE=3, AT-STE=6, or AT-STE=7)

If the modem is off-hook and an extension goes off-hook, the modem

Remo te Ha ng-u p (Enabled by AT-STE=4, AT-STE=5, AT-STE=6, or AT-STE=7)
If the modem is off-hook and the remote user goes on-hook, the modem

Examples:

User is talking on an extension and the modem tries to dial
AT-STE=7
ATDT555-1212
LINE-IN-USE.

The line is not in use and the modem tries to dial
AT-STE=7
ATDT555-1212
Modem goes off-hook
CONNECT

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 24

issues a <DLE>P to the DTE. The application software should then hang

up the line (VLS=0).

issues a <DLE>P to the DTE. The application software should then hang

up the line (VLS=0).

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

An extension is off-hook but there is silence on the line and the modem

tries to dial

AT-STE=3
ATDT555-1212
Modem goes off-hook
NO DIAL TONE

Modem is connected in data mode and remote modem goes on-hook

AT-STE=4

ATDT555-1212

CONNECT

NO CARRIER Remote modem drops line

ATS86=?

025

Modem is in answer machine mode and an extension goes off-hook

AT-STE=2

AT+FCLASS=8

OK

<DLE>h Local handset on-hook

<DLE>R Ring

AT+VLS=1

OK

AT+VSM=1,7200,0,0

AT+VTX Starts to play greeting message

<DLE>P User picks up extension

<DLE>! DTE send abort to end playback

AT+VLS=0 DTE hangs up.

Automated system that needs to periodically use the line while giving the

voice user the highest priority

A common use for these features would be an automated system that

needs to periodically use the line while giving the voice user the highest

priority. The automated system would make a connection when the line is

free. It would do this without disturbing the line if the line is in use. The

automated system would periodically retry the connection until the line is

free. Once the line is free it would dial and make its connection. If a voice

user wishes to use the line while the modem is connected. The modem will

drop the line and give the line to the user. The modem will then try to

regain control of the line by once again periodically retrying to establish a

connection.

AT-STE=7

OK

ATDT5551212

CONNECT

Sometime later, the user picks up phone

NO CARRIER

ATS86?

25

OK

Delay 30 seconds

ATDT5551212

LINE-IN-USE

Try again some time later; user hangs up phone

CONNECT

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 25

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

Modulation Control Commands

Command: +MS Modulation Selection

Description: This extended-format compound parameter controls the manner of

operation of the modulation capabilities in the modem. It accepts six

subparameters.
Syntax: +MS=[<carrier>[,<automode>[,<min_tx_rate>[,<max_tx_rate>
[,<min_rx_rate> [,<max_rx_rate>]]]]]]
Where possible <carrier>, <min_tx_rate>, <max_tx_rate>, <min_rx_rate>,

and <max_rx_rate> values are listed in Table 1-3.

Table 1-3. +MS Command Supported Rates

Modulation <carrier> Possible (<min_rx_rate>, <min_rx_rate>, (<min_tx_rate>),

Bell 103 B103 300
Bell 212 B212 1200 Rx/75 Tx or 75 Rx/1200 Tx
V.21 V21 300
V.22 V22 1200
V.22 bis V22B 2400 or 1200
V.23 V23C 1200
V.32 V32 9600 or 4800
V.32 bis V32B 14400, 12000, 9600, 7200, or 4800
V.34 V34 33600, 31200, 28800, 26400, 24000, 21600, 19200, 16800,

56K K56 56000, 54000, 52000, 50000, 48000, 46000, 44000, 42000,

V.90 V90 56000, 54667, 53333, 52000, 50667, 49333, 48000, 46667,

V.92
downstream

V.92
upstream

Note: Some <carrier> values may not be supported by certain model models. For

example, modem models supporting V92 may not support K56.

V92 56000, 54667, 53333, 52000, 50667, 49333, 48000, 46667,

V92 48000, 46667, 45333, 44000, 42667, 41333, 40000, 38667,

and <max_tx_rate>) Rates (bps)

14400, 12000, 9600, 7200, 4800, or 2400

40000, 38000, 36000, 34000, 32000

45333, 44000, 42667, 41333, 40000, 38667, 37333, 36000,
34667, 33333, 32000, 30667, 29333, 28000

45333, 44000, 42667, 41333, 40000, 38667, 37333, 36000,
34667, 33333, 32000, 30667, 29333, 28000

37333, 36000, 34667, 33333, 32000, 30667, 29333, 28000,
26667, 25333, 24000

Defined Values: <carrier> A string that specifies the preferred modem carrier to

use in originating or answering a connection. <carrier>
values are strings of up to eight characters, consisting
only of numeric digits and upper case letters. <carrier>
values for ITU standard modulations take the form:
<letter><1-4 digits><other letters as needed>. Defined
values are listed in Table 1-3.

<automode> A numeric value which enables or disables automatic

modulation negotiation (ITU-T V.32bis Annex A or V.8).

0 = Automode disabled.

1 = Automode enabled. (Default.)

<min_rx_rate> and <max_rx_rate>

Numeric values which specify the lowest
(<min_rx_rate>) and highest (<max_rx_rate>) rate at
which the modem may establish a receive connection.
May be used to condition distinct limits for the receive
direction as distinct from the transmit direction. Values
for this subparameter are decimal encoded, in units of
bit/s. The possible values for each modulation are listed
in Table 1-3. Actual values will be limited to possible
values corresponding to the entered <carrier> and fall­back <carrier> as determined during operation. (Default

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 26

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

= lowest (<min_rx_rate>) and highest (<max_rx_rate>)
rate supported by the selected carrier.)

<min_tx_rate> and <max_tx_rate>

Numeric values which specify the lowest
(<min_tx_rate>) and highest (<max_tx_rate>) rate at
which the modem may establish a transmit connection.
Non-zero values for this subparameter are decimal
encoded, in units of bit/s. The possible values for each
modulation are listed in Table 1-3.
Actual values will be limited to possible values
corresponding to the entered <carrier> and fall-back
<carrier> as determined during operation. (Default =
lowest (<min_tx_rate>) and highest (<max_tx_rate>)
rate supported by the selected carrier.).

Report Commands: +MS? Reports current rates

Response: +MS:<carrier>,<automode>,<min_tx_rate>,
<max_tx_rate>, <min_rx_rate>,<max_rx_rate>

Note: The current active settings are reported under control of

the +MR parameter.
Example: +MS: K56, 1,300,33600,300,56000
For default values. This example allows maximum system

flexibility to determine optimal receive and transmit rates
during operation.

+MS=? Reports supported range of parameter values:

Response: +MS: (< carrier> range),(<automode>
range),(<min_tx_rate> range), (<max_tx_rate> range),
(<min_rx_rate> range), (<max_rx_rate> range)

Example 1:
+MS:(B103,B212,V21,V22,V22B,V23C,V32,V32B,V34,
K56,V90),(0,1),(300-33600),(300-33600),(300-56000),(300-

56000)
Example 2:

+MS:(B103,B212,V21,V22,V22B,V23C,V32,V32B,V34,
V90,V92),(0,1),(300-33600),(300-33600),(300-56000),(300-

56000)

Result Code: OK - Valid subparameter string
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 27

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

Command: +MR Modulation Reporting Control

Description: This extended-format numeric parameter controls whether or not the

extended-format +MCR:<carrier> and +MRR:<rate> intermediate result

codes are transmitted from the modem to the DTE. If enabled,

+MCR:<carrier> and +MRR:<rate> intermediate result codes represent the

current (negotiated or renegotiated) modulation <carrier> and <rate> that

are transmitted at the point during connect negotiation (handshaking) at

which the modem has determined which modulation and rate will be used,

i.e., before any Error Control or Data Compression reports are transmitted,

and before any final result code (e.g., CONNECT) is transmitted.
S95 bit 2 is reset to 0 for +MR=0 and is set to a 1 for +MR=1 or +MR=2.

The more recent setting of +MR or S95 bit 2, and the W command setting,

determines modulation result code reporting (see S95 Parameter and W

Command).
Default: 0
Defined Values: +MR0 Disables reporting of modulation connection (+MCR: and +MRR:

are not transmitted).

+MR1 Enables reporting of modulation connection (+MCR: and +MRR:

are transmitted with TX rate, RX rate).

+MR2 Enables reporting of modulation connection (+MCR: and +MRR:

are transmitted with RX rate only).
Report Commands: +MR? Reports the current value.
+MR=? Reports supported range of parameter values.

+MCR Report Syntax

Response: +MCR: <carrier>

<carrier> Alphanumeric code corresponding to the reported

carrier. Defined values are:

B103 For Bell 103
B212 For Bell 212
V21 For V.21
V22 For V.22
V22B For V.22bis
V23C For V.23
V32 For V.32
V32B For V.32bis
V34 For V.34
V90 For V.90
K56 For K56flex

+MRR Report Syntax

Response: +MRR: <tx_rate>,<rx_rate>

<tx_rate> Decimal transmit rate in bits/s.
<rx_rate> Decimal receive rate in bits/s.
Example: +MRR: 28800, 48000

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 28

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

Command: %E Enable/Disable Line Quality Monitor and Auto-Retrain or

Fallback/Fall Forward

Description: Controls whether or not the modem will automatically monitor the line

quality and request a retrain (%E1) or fall back when line quality is
insufficient or fall forward when line quality is sufficient (%E2). The
parameter value, if valid, is written to S41 bits 2 and 6.

If enabled, the modem attempts to retrain for a maximum of 30 seconds.

Fallback/Fall Forward. When %E2 is active, the modem monitors the line

quality (EQM). When line quality is insufficient, the modem will initiate a
rate renegotiation to a lower speed within the V.34/V.32 bis/V.32 (RC336)
modulation speeds. The modem will keep falling back within the current
modulation if necessary until the speed reaches 2400 bps (V.34) or 4800
bps (V.32). Below this rate, the modem will only do retrains if EQM
thresholds are exceeded. If the EQM is sufficient for at least one minute,
the modem will initiate a rate renegotiation to a higher speed within the
current modulation speeds. The rate renegotiations will be done without a
retrain if a V.32bis connection is established.

Speeds attempted during fallback/fall forward are those shown to be
available in the rate sequences exchanged during the initial connection.
Fallback/fall forward is available in error correction and normal modes, but

not in direct mode or synchronous mode with external clocks.
Default: 2
Defined Values: %E0 Disable line quality monitor and auto-retrain.
%E1 Enable line quality monitor and auto-retrain.
%E2 Enable line quality monitor and fallback/fall forward. (Default.)
Result Codes: OK
Otherwise ERROR

Command: %U Select µ-Law or A-Law Codec Type

Description: Selects µ-Law or A-Law codec type for V.90 and 56K modulation.
This command also stores the selected setting directly to NVRAM.
Default: Default value is country specific
Defined Values: 0 Selects µ-Law.
1 Selects A-Law.
Result Codes: OK
Otherwise ERROR

Command: B Communication Standard Setting – CCITT or Bell

Description: When the modem is configured to allow either option, the modem will

select Bell or CCITT modulation for a line speed connection of 300 or 1200

bps. Any other line speed will use a CCITT modulation standard. The

parameter value, if valid, is written to S27 bit 6.
Default: B0 (default for MT5600SMI)
B1 (default for MT5656SMI)
Defined Values: B0 Selects CCITT operation at 300 or 1200 bps during Call

Establishment and a subsequent connection. (Default.)

B1 Selects BELL operation at 300 or 1200 bps during Call

Establishment and a subsequent connection.
Result Codes: OK
Otherwise ERROR

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 29

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

Error Control Commands

Command: +ES Error Control and Synchronous Mode Selection

Description: This extended-format command specifies the initial requested mode of

operation when the modem is operating as the originator. Optionally
specifies the acceptable fallback mode of operation when the modem is
operating as the originator; optionally specifies the acceptable fallback
mode of operation when the modem is operating as the answerer. Accepts
three numeric subparameters.

Default: Varies by request

Defined Values: <orig_rqst>

Decimal number specifies the initial requested mode of operation when the
modem is operating as the originator. The options are:
+ES0 Initiate call with Direct Mode.
+ES1 Initiate call with Normal Mode (referred to as Buffered Mode) only.
+ES2 Initiate V.42 without Detection Phase. If V.8 is in use, disable V.42

Detection Phase.

+ES3 Initiate V.42 with Detection Phase. (Default.)

+ES4 Initiate MNP.
+ES6 Initiate V.80 Synchronous Access Mode when connection is

completed and Data State is entered. (See +ESA and +ITF.)

+ES7 Initiate Frame Tunneling Mode when connection is complete and

Data Mode is entered.

<orig_fbk>

Decimal number specifies the acceptable fallback mode of operation when

the modem is operating as the originator.

+ES0 LAPM, MNP, or Normal Mode error control optional. (Default.)

+ES1 LAPM, MNP, or Direct Mode error control optional.
+ES2 LAPM or MNP error control required; disconnect if error control is

not established.

+ES3 LAPM error control required; disconnect if error control is not

established.

+ES4 MNP error control required; disconnect if error control is not

established.

<ans_fbk>

Decimal number specifies the acceptable fallback mode of operation when
the modem is operating as the answerer or specifies V.80 Synchronous
Access Mode.
+ES0 Direct Mode.
+ES1 Error control disabled, use Normal Mode.
+ES2 LAPM, MNP, or Normal Mode error control optional. (Default.)
+ES3 LAPM, MNP, or Direct Mode error control optional.
+ES4 LAPM or MNP error control required; disconnect if error control is

not established.

+ES5 LAPM error control required; disconnect if error control is not

established.

+ES6 MNP error control required; disconnect if error control is not

established.

+ES8 Initiate V.80 Synchronous Access Mode when connection is

completed and Data State is entered (see +ESA and +ITF).

+ES9 Initiate Frame Tunneling Mode when connection is complete and

Data Mode is entered.
Examples: +ES=6 Enable V.80 Synchronous Access Mode originator.
+ES=6 Enable V.80 Synchronous Access Mode originator.
+ES=,,8 Enable V.80 Synchronous Access Mode answerer.
+ES=6,,8 Enable V.80 Synchronous Access Mode.

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C) 30