Multitech MT1932ZDXI Operating manual

MultiModem®& SocketModem®
MT9234 Series
AT Commands
Reference Guide

Copyright and Technical Support
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 2
AT Commands Reference Guide for the MultiModem and SocketModem MT9234 Series
MT9234SMI
MT9234ZBA
MT9234ZBA-USB
MT9234MU
MT9234ZPX-UPCI
MT9234ZPX-PCIE
ISI9234PCIE
PN S000434D, Version D
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 © 2007-2008, by Multi-Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranty 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
A04/13/07 Initial release.
B 07/12/07 Updated the Escape Sequence text. Added a statement indicating that
some commands may not apply to every MT9234 build option. Deleted
the $LL command. Updated the $LB command.
08/09/07 Added a note that Voice commands other individual commands cannot
be used with the SMI build.
C 10/17/07 Added ISI9234PCIE to the product list to which these commands apply.
Updated the Technical Support list.
D 03/25/08 Removed +VDT command. Removed S2 range of 128-255. Changed
S24 default to 0. Changed S89 default to 0 and range to 0, 5-65.
Changed Communciation Standard Setting command "B" default to 0,15.
Added values 4 and 6 to &T command.
Trademarks
Multi-Tech registered trademarks include the Multi-Tech logo, MultiModem, and SocketModem.
World Headquarters
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, MN 55112
Phone: [phone] or 800-328-9717
Fax: [phone]
Internet Address: http://www.multitech.com
Technical Support
Country By Email By Phone
Europe, Middle East, Africa [email protected]k +(44) 118 959 7774
U.S., Canada, all others [email protected]m [phone] or +[phone]

Table of Contents
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 3
Contents
Chapter 1 – AT Commands, S-Registers, and Result Codes .................................................................6
Introduction................................................................................................................................................6
A Note About Fax Commands...................................................................................................................6
Data and General Commands...................................................................................................................7
AT Attention Code...........................................................................................................................7
ENTER Key...........................................................................................................................................7
+++AT Escape Sequence...............................................................................................................7
A/ Repeat Last Command.................................................................................................................7
AAnswer..........................................................................................................................................7
BCommunication Standard Setting.................................................................................................7
DDial................................................................................................................................................8
EEcho Command............................................................................................................................9
FOnline Data Character Echo Command.......................................................................................9
HHook Control.................................................................................................................................9
IRequest ID Information...............................................................................................................10
MMonitor Speaker Mode ...............................................................................................................10
NModulation Handshake...............................................................................................................11
OReturn Online to Data Mode.......................................................................................................11
PSet Pulse or Tone Dialing Default...............................................................................................11
QResult Codes Enable/Disable.....................................................................................................11
Sr= S-Register Control...................................................................................................................12
TSelect Tone Dialing.....................................................................................................................12
VResult Code Format....................................................................................................................12
WResult Code Options...................................................................................................................12
XSelect Result Code and Monitor Call Progress..........................................................................13
ZReset and Recall Stored Profile..................................................................................................13
&C Data Carrier Detect (DCD) Control..........................................................................................14
&D Data Terminal Ready (DTR) Control.......................................................................................14
&E XON/XOFF Pacing Control......................................................................................................14
&F Restore Factory Default Configuration....................................................................................14
&G V.22bis Guard Tone Control....................................................................................................15
&K Local Flow Control Selection...................................................................................................15
&L Leased Line Operation............................................................................................................15
&P Pulse Dial Make-to-Break Ratio Selection ..............................................................................15
&Q Asynchronous Communications Mode....................................................................................16
&S Data Set Ready (DSR)............................................................................................................16
&T Self-Test Commands...............................................................................................................16
&V View Active Configuration........................................................................................................16
&W Store Current Configuration.....................................................................................................17
&Z Store Dialing Location and Number ........................................................................................17
\A Select Maximum MNP Block Size ..............................................................................................17
\B Transmit Break............................................................................................................................17
\K Break Control..............................................................................................................................18
\N Error Correction Mode Selection ................................................................................................18
\Q Local Flow Control Selection......................................................................................................19
\T Inactivity Timer............................................................................................................................19
\V Protocol Result Code..................................................................................................................19
\X XON/XOFF Pass-Through..........................................................................................................19
-C Data Calling Tone ......................................................................................................................19
%A Adaptive Answer Result Code Enable ....................................................................................20
%B View Numbers in Blacklist.......................................................................................................20
%C Data Compression Control......................................................................................................20
%DC AT Command Control...........................................................................................................20
%DT Set AT Command Mode Timer ............................................................................................21

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 4
%E Fallback and Fall Forward Control...........................................................................................21
%H Set Callback Security – Direct Connect Enable......................................................................21
%S Command Speed Response ...................................................................................................21
+A8E V.8 and V.8bis Operation Controls......................................................................................22
+A8T Send V.8 bis Signal and/or Message...................................................................................23
+DCS Select V.42bis or V.44 Data Compression...........................................................................23
+DR V.44 Data Compression Reporting..........................................................................................24
+DS V.42bis Data Compression......................................................................................................24
+DS44 V.44 Data Compression....................................................................................................25
+EB Break Handling in Error Control Operation..............................................................................26
+EFCS 32-bit Frame Check Sequence.........................................................................................26
+ER Error Control Report................................................................................................................26
+ES Error Control Selection............................................................................................................27
+ESA Set Up Error Control Parameters.........................................................................................27
+ETBM Call Termination Buffer Management...............................................................................27
+FCLASS Fax Class Indication .......................................................................................................28
+GCAP Complete List of Capabilities Request..............................................................................28
+GCI Country of Installation...........................................................................................................28
+GMI Manufacturer Identification Request ....................................................................................28
+GMM Model Identification Request.............................................................................................28
+GMR Revision Request.................................................................................................................28
+IFC DTE-DCE Local Flow Control ..............................................................................................29
+ILRR DTE-DCE Local Rate Reporting ..........................................................................................29
+IPR= Fixed DTE Rate....................................................................................................................29
+ITF= Transmit Flow Control Threshold.........................................................................................30
+MR Modulation Reporting Control ..............................................................................................30
+MS Modulation Selection............................................................................................................30
$D DTR Dialing .............................................................................................................................32
$EB Asynchronous Word Length....................................................................................................32
$LB Long Break ..............................................................................................................................32
$MB Online BPS Speed ...............................................................................................................32
$RP Ring Priority vs. AT Command Priority....................................................................................33
$SB Serial Port Baud Rate..............................................................................................................33
+VDR Distinctive Ring Report.........................................................................................................33
#CBS Callback Enable/Disable ......................................................................................................36
#P Set 11-bit Parity.......................................................................................................................34
#S Enter Setup Password.............................................................................................................34
#S= Store Setup Password.............................................................................................................34
%%%ATMTSMODEM<CR> Remote Configuration Escape Sequence .........................................34
+VCID= Caller ID Selection ............................................................................................................34
Callback Security Commands..................................................................................................................35
#CBA Callback Attempts ................................................................................................................35
#CBD Callback Delay .....................................................................................................................35
#CBF? Callback Failed Attempts Display .....................................................................................35
#CBFR Callback Failed Attempts Reset........................................................................................35
#CBI Local Callback Inactivity Timer.............................................................................................35
#CBN Store Callback Password.....................................................................................................35
#CBP Callback Parity .....................................................................................................................36
#CBR Callback Security Reset.......................................................................................................36
S-Registers..............................................................................................................................................37
Result Codes ...........................................................................................................................................40
Chapter 4 – Voice Commands .................................................................................................................42
Introduction..............................................................................................................................................42
Voice S-Register Summary .....................................................................................................................43
Voice Commands.....................................................................................................................................43
Commands That Change for Voice Mode Support..................................................................................43
Voice +V Commands Detail.....................................................................................................................44

Table of Contents
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 5
+FCLASS= 8 Select Voice Mode....................................................................................................44
+VNH Automatic Hang-Up Control .................................................................................................44
+VIP Initialize Voice Parameters...................................................................................................44
+VRX Enter Voice Receive State ...................................................................................................44
+VTS Send Voice Tone(s)..............................................................................................................45
+VTX Start Voice Transmission Process.......................................................................................46
+VGR Voice Gain for Received Voice Samples .............................................................................46
+VGT Set the Volume for Transmitted Voice Samples ..................................................................46
+VIT Set DTE/DCE Inactivity Timer..............................................................................................47
+VLS Select Analog Source/Destination........................................................................................48
+VRA Ringback Goes Away Timer.................................................................................................49
+VRN Ringback Never Appeared Timer.........................................................................................49
+VSD Silence Detection Sensitivity................................................................................................50
+VSM Select Voice Compression Method......................................................................................51
+VTD=<dur> Beep Tone Duration Timer (DTMF/Tone Generation Duration)................................52
+VDR Distinctive Ring (Ring Cadence Reporting)..........................................................................53
+VEM Event Reporting and Masking..............................................................................................54
Interface Configuration Commands.........................................................................................................55
+VBT Set Modem Flow Control Assert and Deassert Points.........................................................55
+VPP Enable or Disable Voice Mode Packet Protocol...................................................................56
+VPR Select DTE/DCE Interface Rate (Turn Off Autobaud)..........................................................56
Flow Control.............................................................................................................................................57
Voice Mode Result Codes .......................................................................................................................57
Unsolicited Voice Mode Result Codes.....................................................................................................58
Valid Complex Event Report Tags......................................................................................................58
Voice Mode Shielded Codes ...................................................................................................................59
DTE/DCE Interface Rates........................................................................................................................61
Index...........................................................................................................................................................62

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 6
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 (+++AT) and the command, 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 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 Xis the command and nis 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”.
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 messages 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.
Note: This document applies to all the MT9234 products. However, some commands may not apply to all
MT9234 builds.
A Note About Fax Commands
Fax commandsare covered in two separate fax reference guides. These guides are included on the
product CD and are posted on the Multi-Tech Web site:
http://www.multitech.com/DOCUMENTS/Families/MultiModemZBA/manuals.asp.
•Fax Service Class 1 and Fax Service Class 1.0 Developer's Guide.
Document number: S000262x
•Fax Developer's Guide for Classes 2 and 2.0/2.1
Document number: S000239x

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 7
Data and General Commands
AT Attention Code
Description: The attention code precedes all command lines except A/, A: and escape sequences.
ENTER Key
Description: Press the ENTER (RETURN) key to execute a command.
+++AT Escape Sequence
Syntax: +++AT<CR>
Description: Allows the modem to exit data mode and enter on-line command mode. While in on-
line command mode, AT commands are sent directly to the modem.
Use the return to on-line data mode command (O<value> – Return to On-Line Data
Mode) to return to data mode.
A/ Repeat Last Command
Syntax: A/
Description: This command repeats the last AT command. The modem repeats the command
currently in the command buffer.
IMPORTANT:
Do not use the AT prefix with this command.
Do not conclude the command with a terminating character (ENTER).
A Answer
Syntax: ATA
Description: This command instructs the modem to connect to the line and establish a connection
with the remote modem or DCE. This command can be canceled if the modem
receives a new command or character from the host system before the handshake
begins.
Result Codes: CONNECT if a connection is established and the extended result code parameter is
equal to 0. (See X<value> – Select Result Code and Monitor Call Progress).
CONNECT <rate> if a connection is established and the extended result code
parameter is not equal to 0.
NO CARRIER if a connection cannot be established or the modem aborts the
connection on request of the host system.
OK if the commands are aborted or DTR is turned off by the host system when the
data terminal ready control is not set to 0. See &D – DTR Control.
ERROR if the modem is in on-line command mode when receiving the Acommand.
B Communication Standard Setting
Description: This command selects the communication standard used by the modem.
Syntax: ATB<value>
Values: 0 Selects CCITT V.22 mode when modem is at 1200 bps.
1 Select Bell 212A when modem is at 1200 bps.
2 Deselect V.23 reverse channel (same as B3).
3 Deselect V.23 reverse channel (same as B2).
15 Select V.21 when the modem is at 300 bps.
16 Select Bell 103J when the modem is at 300 bps.
Defaults: 0 and 15
Result Codes: OK if <value> = 0-3, 15, 16
ERROR if <value> ≠1.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 8
D Dial
Description: This command instructs the modem to begin the dialing sequence. The dial string,
which is made up of the telephone number and dial modifiers is entered after the D
command.
A dial string can be up to 60 characters long. Any digit or symbol may be dialed as
touchtone digits. Characters such as spaces, hyphens, and parentheses are ignored
by the modem and may be included in the dial string to enhance readability.
Syntax: ATD<dial_strings>
Dial String Values: Phone number and dial modifiers.
Dial string modifiers:
L Redial the last number. (Must be placed immediately after ATD.)
P Select pulse-dialing.
TSelect tone-dialing.
VDial using speakerphone. Instructs the modem to switch to speakerphone
mode and dial the number. Use the ATH command to disconnect the voice
call.
WWait for dial tone. This command instructs the modem to wait for a second
dial tone before processing the dial string.(X2, X4, X5, X6, or X7 must be
selected.)
,Pause during dialing for the amount of time set in register S8.
;Return to command mode. Instructs the modem to return to command mode
after it has finished dialing without disconnecting the call. This modifier must
be the last character in the dial string.
!Hook flash. Instructs the modem to go on-hook for 0.5 seconds and then
return to off-hook.
@ Wait for quiet answer. Instructs the modem to wait for 5 seconds of silence
after dialing the number. If silence is not detected, the modem sends a NO
ANSWER result code back to the user.
^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
S=<location> Dial a number previously stored in the register. Instructs the modem
to dial a telephone number previously stored using the
&Z<location>=<dial_string> command. Valid storage locations are 0 to 2
(0–1 for Parallel {internal}).
Example: ATDS=2
Default: T
Result Codes: CONNECT if a connection is established and the extended result code
parameter is equal to 0. (See X<value> – Select Result Code and
Monitor Call Progress).
CONNECT <rate> if a connection is established and the extended result code
parameter is not equal to 0.
NO CARRIER if a connection cannot be established or the modem aborts the
connection on request of the host system.
BUSY if the Wor @modifiers are used and a busy signal is detected.
NO ANSWER if the @modifiers is used and the remote ring followed by 5
seconds of silence is not detected before expiration of the connection
timer. See S7 – Connection Completion Time-Out.
OK if the commands are aborted or DTR is turned off by the host system when
the data terminal ready control is not set to 0. See &D<value> – Data
Terminal Ready (DTR) Control.
ERROR if the modem is in on-line command mode when receiving the A
command.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 9
E Echo Command
Description: Enables or disables the modem's echo feature. When the echo feature is selected
and the modem is in the command mode, characters sent to the modem are sent
back to the host and displayed on the monitor.
Syntax: ATE<value>
Values: 0 Do not echo keyboard input to the terminal.
1 Do echo keyboard input to the terminal.
Default: 1
F Online Data Character Echo Command
Description: Controller-based products support this command to ensure backward compatibility
with communications software that issues the F1 command.
Syntax: ATF<value>
Values: 0 Enable online data character echo. (Not supported.)
1 Disable online data character echo (included for backward compatibility).
Default: 1
Result Codes: OK if <value> = 1
ERROR if <value> ≠1.
H Hook Control
Description: Instructs the modem to go on-hook to disconnect a call or go off-hook to make the
telephone line busy.
Syntax: ATH<value>
Values: 0 Go on-hook (hang up).
1 Go off-hook (make the phone line busy).
Default: 0
Result Codes: OK if <value> = 0 to 1
ERROR if <value> ≠0 to 1.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 10
I Request ID Information
Description: Use this command to display product information about the modem. In each case the
information is transmitted to the host system followed by a final result code.
Syntax: ATI<value>
Values: 0, 3 Returns the modem identity string and driver version number.
1 Calculates a ROM checksum and displays it on the DTE (e.g., 12AB).
2 Performs a ROM check, calculates the checksum, and then verifies the
checksum by displaying OK or ERROR.
4 Returns firmware version for the data pump (e.g., 94).
5 Returns the code version, board ID, and country/region ID in hexadecimal.
9 Returns the country/regional code in English.
11 Displays connection information as described below.
Default: 0
Result Codes: The ATI11 results are listed on two screens. To get to the second screen, press any
key or ESC to Exit. The following is an example of the ATI11 results.
Description Status
Last Connection V.92
Initial Transmit Carrier Rate 28800
Initial Receive Carrier Rate 50666
Final Transmit Carrier Rate 28800
Final Receive Carrier Rate 50666
Protocol Negotiation Result LAPM
Data Compression Result V44
Estimated Noise Level 46
Receive Signal Power Level (-dBm) 18
Transmit Signal Power Level (-dBm) 12
Round Trip Delay (msec) 10
Description Status
Near Echo Level (-dBm) NA
Far Echo Level (-dBm) NA
Transmit Frame Count 0
Transmit Frame Error Count 0
Receive Frame Count 1
Receive Frame Error Count 0
Retrain by Local Modem 0
Retrain by Remote Modem 0
Rate Renegotiation by Local Modem 0
Rate Renegotiation by Remote Modem 0
Call Termination Cause 0
Robbed-Bit Signaling 10
Digital Loss (dB) 6
Remote Server ID NA
Last PCM S PTR EBB3
Connection Time (msec) 19646
The ATI11 command may be issued from on-line command mode or after the end of
a call. After a call, some of the values are no longer valid.
M Monitor Speaker Mode
Description: Turns the speaker on and off.
Syntax: ATM<value>
Values: 0 Speaker always off.
1 Speaker on until carrier signal detected.
2 Speaker always on when modem is off-hook.
3 Speaker on until carrier is detected, except while dialing.
Default: 1
Result Codes: OK if <value> = 0 to 3
ERROR if <value> ≠0 to 3.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 11
N Modulation Handshake
Description: Sets the modem protocol for handling handshake negotiation at connection time if
the communication speed of the remote modem is different from the speed of the
ATN<value>
Values: 0 Modem performs handshake only at communication standard specified by S-
Register S37 and the B<value> command.
1 Modem begins handshake at communication standard specified by S-Register
S37 and the B command. During handshake, fallback to a lower speed can
occur.
Default: 1
Result Codes: OK if <value> = 0 to 1
ERROR if <value> ≠0 to 1.
O Return Online to Data Mode
Description: Exits online command mode and enters online data mode. If the modem is not in
online command mode when this command is received, the modem generates an
ERROR result code.
Syntax: ATO<value>
Values: 0 Exits online command mode and returns to data mode.
1 Issues a retrain before returning to online data mode.
3 Issues a rate renegotiations before returning to online data mode.
Default: 0
Result Codes: CONNECT if <value> = 0, 1, 3 and result code and call progress monitor are set to 0
(X0).
CONNECT <rate> if <value> = 0, 1, 3 and the result code and call progress monitor
are not set to 0 (X<value> where n = 1 to 7).
NO CARRIER if the connection is not successfully resumed.
ERROR if <value> ≠0, 1, 3.
P Set Pulse or Tone Dialing Default
Description: Configures the modem for pulse (non-touch-tone) or Tone dialing. All subsequent
D<dial_string> commands use pulse dialing until either the Tcommand or a tone
dial modifier is received by the modem. Tone dialing is the default setting. This
command does not use parameters and generates an ERROR result code when
parameters are attached to the command.
Syntax: ATP
Values: P Pulse Dialing
TTone Dialing
Default: T
Q Result Codes Enable/Disable
Description: Result codes are informational messages sent from the modem and displayed on the
monitor. Basic result codes include OK, CONNECT, RING, NO CARRIER, and
ERROR.
Use the Q<value> command to enable or disable result code generation by the
modem. If result codes are disabled and an invalid parameter value is entered, the
modem does not generate an ERROR result code because result codes are turn off.
Syntax: ATQ<value>
Values: 0 Enable result codes.
1 Disable result codes.
Default: 0
Result Codes: OK if <value> = 0 to 1
ERROR if <value> ≠0 to 1.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 12
Sr= S-Register Control
Description: Use this command to view or change an S-register. S-registers contain parameters
used by the modem. This command has two forms, one to show the contents of the
register and the other to change the contents of the register. Some registers are read
only and are not affected by the S<register number>=<value> command. Each
register has a specific function.
Syntax: ATS<register number>=<value> Sets the contents of the register to <value> if the
register is not read only.
ATS<register number>? Displays register contents.
Default: None
Result Codes: OK if <register number> is a valid register.
ERROR if <register number> is not a valid register.
T Select Tone Dialing
Description: Configures the modem for DTMF (touch-tone) dialing. All subsequent D<dial string>
commands use tone dialing until either the Pcommand or a pulse dial modifier is
received by the modem. Tone dialing is the default setting. This command does not
use parameters and generates an ERROR result code when parameters are
attached to the command.
Syntax: ATT
V Result Code Format
Description: Controller-based modems generate result codes using one of two formats. Verbose
mode generates result codes in the familiar text formats using words. Numerical
mode generates result codes as a number. Each result codes has a number
assigned to it.
Use this command to switch between numerical and verbose modes.
Call progress and negotiation progress messages are affected by this command.
Syntax: ATV<value>
Values: 0 Displays result codes as digits (terse response).
1 Displays result codes as words (verbose response).
Default: 1
Result Codes: OK if <value> = 0 to 1.
ERROR if <value> ≠0 to 1.
W Result Code Options
Description: Use this command to select the modem's CONNECT message options.
Syntax: ATW<value>
Values: 0 CONNECT result code reports DTE receive speed; disables protocol result
codes.
1 CONNECT result code reports DTE receive speed; enables protocol result
codes.
2 CONNECT result code reports DCE receive speed; enables protocol result
codes.
Default: 2
Result Codes: OK if <value> = 0 to 2.
ERROR if <value> ≠0 to 2.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 13
X Select Result Code and Monitor Call Progress
Description: Use this command to enable tone detection options used in the dialing process. As
each function is chosen, the modem’s result codes are also affected. Therefore, this
command is frequently used to control the modem’s responses. The primary function
of this command is to control call response capabilities.
Function Enabled Disabled
Ext Result Codes Modem displays basic result
codes, connect messages with
data rate, and an indication of
the modems error correction
and data compression
operations.
Modem displays the basic
result codes.
Dial Tone Detect
Modem dials upon detection of a dial tone, and disconnects the
call if the dial tone is not
detected within 10 seconds.
Modem dials a call regardless
of whether it detects a dial
tone. Register S6 contains
the dial delay.
Busy Tone Detect Modem monitors for busy tones. Modem ignores any busy
tones it receives.
Syntax: ATX<value>
Values: Command Extended Result Codes Dial Tone Detect Busy Tone Detect
0Disabled Disabled Disabled
1 Enabled Disabled Disabled
2 Enabled Enabled Disabled
3 Enabled Disabled Enabled
4 Enabled Enabled Enabled
5, 6 Enabled Enabled Enabled
7 Disabled Enabled Enabled
Default: 4
Result Codes: OK if <value> = 0 to 7.
ERROR if <value> ≠0 to 7.
Call Progress Result Codes:
Command Result Codes
0OK, RING, ERROR, CONNECT, NO CARRIER
1OK, RING, ERROR, CONNECT<RATE>, NO CARRIER
2OK, RING, ERROR, CONNECT<RATE>, NO CARRIER, NO DIALTONE
3OK, RING, ERROR, CONNECT<RATE>, NO CARRIER, BUSY,
BLACKLISTED
4OK, RING, ERROR, CONNECT<RATE>, NO CARRIER, BUSY,
BLACKLISTED, DELAYED, NO DIALTONE, CALL WAITING
DETECTED
5, 6 OK, RING, ERROR, CONNECT<RATE>, NO CARRIER, BUSY,
BLACKLISTED, DELAYED, NO DIALTONE, CALL WAITING
DETECTED
7OK, RING, ERROR, CONNECT, NO CARRIER
Z Reset and Recall Stored Profile
Description: Use this command to make the modem go on-hook and restore the profile saved by
the last &W command.
Note: Both Z0 or Z1 restore the same profile (See &W – Store Current Configuration).
Agere Systems controller-based modems have only one stored profile.
Syntax: ATZ<value>
Values: 0 Reset and restore stored profile (saved by the last &W command).
1 Same as Z0.
Default: None
Result Codes: OK if <value> = 0 to 1.
ERROR if <value> ≠0 to 1.

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 14
&C Data Carrier Detect (DCD) Control
Description: Use this command to control the modem’s response to receiving a remote modem's
carrier signal. Data carrier detect (DCD) is a signal from the modem to the computer
indicating that the carrier signal is being received from a remote modem. The modem
typically turns off DCD when it no longer detects the remote modem's carrier signal.
Syntax: AT&C<value>
Values: 0 DCD remains ON at all times.
1 DCD turns ON when the remote modem’s carrier signal is detected, and
turns OFF when the carrier signal is not detected.
Default: 1
Result Codes: OK if <value> = 0 to 1.
ERROR if <value> ≠0 to 1.
&D Data Terminal Ready (DTR) Control
Description: Use this command to select the modem’s response to the data terminal ready (DTR)
signal. The host system generates the DTR signal and supplies it to the modem.
Syntax: AT&D<value>
Values: 0 Modem ignores true status of DTR signal and treats it as always on. Use this
command if the computer does not provide DTR to the modem.
1 If DTR is not detected while in online data mode, the modem enters
command mode, issues an OK, and remains connected.
2 If DTR signal is not detected while in online data mode, the modem
disconnects.
3 Resets the modem on the on-to-off DTR transition.
Default: 2
Result Codes: OK if <value> = 0 to 3.
ERROR if <value> ≠0 to 3.
&E XON/XOFF Pacing Control
Description: Enables or disables XON/XOFF pacing.
Syntax: AT&E<value>
Values: 12 Disables XON/XOFF pacing.
13 Enables XON/XOFF pacing.
Default: 12
Result Codes: OK if <value> = 12 to 13.
ERROR if <value> ≠12 to 13.
&F Restore Factory Default Configuration
Description: Use this command to reset the modem to the configuration programmed at the
factory. This operation replaces all of the command options* and S-register settings
in the active configuration with factory default values.
Note: In voice mode, the command line is ignored if the AT&F command is placed on
the same line as the other commands. To load factory settings in voice mode, issue
the &F<value> command by itself.
Syntax: AT&F<value>
Values: 0 Loads factory settings as active configuration.
Default: None
Result Codes: OK if <value> = 0.
ERROR if <value> ≠0.
* There are several noted exceptions to this command and caution should be used
when determining the state of the command options once this command has been
executed.

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 15
&G V.22bis Guard Tone Control
Description: Use this command to select which guard tone, if any, the modem will send while
transmitting in the high band (answer mode). This command is only used in V.22 and
V.22 bis mode. This option is not used in North America; it is for international use
only.
Syntax: AT&G<value>
Values: 0 Disables guard tone.
1 Sets guard tone to 550 Hz.
2 Sets guard tone to 1800 Hz.
Default: 0
Result Codes: OK if <value> = 0 to 2.
ERROR if <value> ≠0 to 2.
Note: The &G command is not used in North America.
&K Local Flow Control Selection
Description: Use this command to select a flow control method.
Syntax: AT&K<value>
Values: 0 Disables flow control.
3 Enables CTS/RTS hardware flow control.
4 Enables XON/XOFF software flow control.
Default: 3
Result Codes: OK if <value> = 0, 3, or 4.
ERROR if <value> ≠0, 3, or 4.
&L Leased Line Operation
Description: Sets standard dial-up or leased-line operation. Note: This command does not apply
to all models or build options.
Syntax: AT&L<value>
Values: 0 The modem is set for standard dial-up operation.
1 The modem is set for leased line operation in originate mode.
2 The modem is set for leased line operation in answer mode.
Default: 0
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.
Result Codes: OK if <value> = 0 to 2.
ERROR if <value> ≠0 to 2.
&P Pulse Dial Make-to-Break Ratio Selection
Description: Use this command to select the make-to-break ratio. This command is effective only
for Japan.
Syntax: AT&P<value>
Values: 0 Selects 39% to 61% make-to-break ratio at 10 pulses per second.
1 Selects 33% to 67% make-to-break ratio at 10 pulses per second.
2 Selects 33% to 67% make-to-break ratio at 20 pulses per second.
Default: 1
Note: The &P2 command is available only if the country/regional code is set to
Japan.
Result Codes: OK if <value> = 0 to 2.
ERROR if <value> ≠0 to 2.

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 16
&Q Asynchronous Communications Mode
Description: This command is supported to ensure backward compatibility with communication
software that issues the &Q command. The preferred method for changing the
asynchronous communication mode is to use the \N command.
Syntax: AT&Q<value>
Values: 0 Asynchronous with data buffering. Same as \N0.
5 Error control with data buffering. Same as \N3.
6 Asynchronous with data buffering. Same as \N0.
8 MNP error control mode. If MNP error control is not established, the modem
falls back according to the setting in S36.
9 V.42 or MNP error control mode. If neither error control is established, the
modem falls back according to the setting in S36.
Default: 5
Result Codes: OK if <value> = 0, 5, 6, 8, or 9.
ERROR if <value> ≠0, 5, 6, 8, or 9.
&S Data Set Ready (DSR)
Description: Use this command to control DSR action.
Syntax: AT&S<value>
Values: 0 DSR is always ON.
1 DSR goes ON only during a connection.
Default: 0
Result Codes: OK if <value> = 0,1.
ERROR if <value> ≠0, 1.
&T Self-Test Commands
Description: Use this command to perform diagnostic tests on the modem. Each test is designed
to isolate a problem location when experiencing periodic data loss or random errors.
Syntax: AT&T<value>
Values: 0 Terminates the test in progress.
1 The &T1 command runs the Local Analog Loopback Test. This test verifies
modem's transmitter and receiver circuits are functioning properly. To work
properly, the modem must be off-line.
3 The AT3 runs the Local Digital Loopback Test. This test allows you to verify
that the remote computer or terminal, the remote modem, serial ports, the
telephone line, and the local modem are functioning properly. To work
properly, the modem must be online.
4 The &T4 command must be sent to the remote modem to run the Remote
Digital Loopback Test.
6 The &T6 command runs the Remote Digital Loopback Test. This test allows
you to verify that the local computer or terminal, the two modems, and the
transmission line between them are functioning properly.To work properly,
the modem must be online.
Default: None
Result Codes: OK if <value> = 0.
CONNECT if <value> = 0 or 3.
ERROR if <value> ≠0, 1, or 3.
&V View Active Configuration
Description: Use this command to view the active configuration.
Syntax: AT&V

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 17
&W Store Current Configuration
Description: Use this command to store the modem's command options and all S- registers
except S3, S4, and S5. The Z0 command or a power-up reset of the modem restores
these profiles.
Note: This command is not valid during a cellular call.
Syntax: AT&W<value>
Values: 0 Stores current configuration as profile 0.
Default: 0
Result Codes: OK if <value> = 0.
ERROR if <value> ≠0.
&Z Store Dialing Location and Number
Description: Use this command to store a dialing string. Controller-based modems can save four
dialing stings. The format for the command is: &Z<storage_location> =
<dialing_string>. The dial string may contain up to 40 characters. The
ATDS=<storage_location> command dials using the stored string.
Syntax: AT&Z<location>=<stored number>
Values: <storage_location> = 0 to 2 for serial; 0 to 1 for parallel.
<dialing_string> = Dialing command.
Default: None
Result Codes: OK if <value> = 0 to 2.
ERROR if <value> ≠0 to 2.
\A Select Maximum MNP Block Size
Description: Use this command to select a MNP error corrected link with a maximum block size
controlled by the parameter <block size>.
Syntax: AT\A<value>
Values: 0 64-character maximum
1 128-character maximum
2 192-character maximum
3 256-character maximum
Default: 3
Result Codes: OK if <value> = 0 to 3.
ERROR if <value> ≠0 to 3.
\B Transmit Break
Description: Use this command in non-error-controlled mode. The command causes the modem
to transmit a break signal to the remote modem. The minimum break length is 100
ms and the maximum break length is 900 ms. The <break_time> parameter has
values between one and nine with each increment representing 100 ms. The default
of <value> = 3 corresponds to a length of 300 ms.
The command works in conjunction with the \K command.
Syntax: AT\B<value>
Values: <break_time> = 0–9 in 100 ms units
Default: 3 (300 ms)
Result Codes: OK if <value> = 0, 1.
ERROR if <value> ≠0, 1.

Chapter 1 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 18
\K Break Control
Description: Use this command to control the response of the modem to a break received from
the DTE, remote modem, or the \B<value> command. The command values are
different in three situations:
Syntax: AT\K<value>
Values: \K<value> – Modem Is Operating in Data Transfer Mode
The modem receives a break from the DTE when it is operating in data transfer
mode. Values Function
0, 2, 4 Enter online command mode, no break sent to remote modem.
1 Clear data buffers and send a break to remote modem.
3 Send a break to the remote modem immediately.
5 Send a nondestructive, nonexpedited break to remote modem.
5 is the default.
\K<value> – Modem Is in Online Command Mode During Data Connection
The modem is in the online command state (waiting for AT commands) during a data
connection, and the \B<value> command is received in order to send a break to the
remote modem.
Values Function
0, 1 Clear data buffers and send break to the remote modem.
2, 3 Send a break to the remote modem immediately.
4, 5 Send a break to the remote modem in sequence with data.
4, 5 are the defaults.
\K<value> – Break Is Received During Connection
The modem receives a break from the remote modem during a connection.
Values Function
0, 1 Clear data buffers and send break to the DTE.
2, 3 Send a break to the DTE immediately.
4, 5 Send a break to the DTE in sequence with the received data.
4, 5 are the defaults.
Result Codes: OK if <value> = 0 to 5.
ERROR if <value> ≠0 to 5.
\N Error Correction Mode Selection
Description: Use this command to select the type of error control used by the modem when
sending or receiving data.
Syntax: AT\N<value>
Values: 0 Buffer mode. No error control (same as &Q6).
1 Direct mode.
2 MNP or disconnect mode. The modem attempts to connect using MNP2-4
error control procedures. If this fails, the modem disconnects. This is also
known as MNP reliable mode.
3 V.42, MNP, or buffered. The modem attempts to connect in V.42 error control
mode. If this fails, it will attempt to connect in MNP mode. If this fails, the
modem connects in buffer mode and continues operation. This is also known
as V.42/MNP auto reliable mode (same as &Q5).
4 V.42 or disconnect. The modem attempts to connect in V.42 error control
mode. If this fails, the modem disconnects.
5 V.42, MNP, or buffered (same as \N3).
7 V.42, MNP, or buffered (same as \N3).
Default: 3
Result Codes: OK if <value> = 0 to 5, or 7.
ERROR if <value> ≠0 to 5, or 7.

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 19
\Q Local Flow Control Selection
Description: Use this command to set the local flow control method.
Syntax: AT\Q<value>
Values: 0 Disable flow control (same as &K0).
1 XON/XOFF software flow control (same as &K4).
3 RTS/CTS to DTE. (same as &K3)
Default: 3
Result Codes: OK if <value> = 0, 1, 3.
ERROR if <value> ≠0, 1, 3.
\T Inactivity Timer
Description: Use this command to specify the delay time used by the inactivity timer. The delay
time is the length of time in minutes that the modem waits during periods of inactivity
before disconnecting. Periods of inactivity are defined by no data being sent or
received by the DCE. To disable the inactivity timer use the T0 command. The delay
time may also be specified in S-register S30.
Syntax: AT\T<value>
Values: 0 Inactivity timer disabled.
1 to 255 Specifies the length of time in minutes that the modem will wait before
disconnecting when no data is sent or received.
Default: 0
Result Codes: OK if <value> = 0 to 255.
ERROR if <value> ≠0 to 255.
\V Protocol Result Code
Description: Use this command to enable or disable protocol result codes.
Syntax: \V<value>
Values: \V0 Disables protocol result code appended to the DCE speed.
\V1 Enables protocol result code appended to the DCE speed.
\V2 Same as \V1.
Default: \V1
Result Codes: OK if <value> = 0, 1, 2.
ERROR if <value> ≠0, 1, 2.
\X XON/XOFF Pass-Through
Description: Use this command to restrict the XON/XOFF flow control to the local DCE for
processing or have the local DCE send the flow control characters to the remote
DCE.
Syntax: AT\X<value>
Values: 0 Modem processes XON/XOFF flow control characters locally.
1 Modem passes XON/XOFF flow control characters.
Default: 0
Result Codes: OK if <value> = 0, 1.
ERROR if <value> ≠0, 1.
-C Data Calling Tone
Description: Enables or disables the V.25 data calling tone to deny or allow data/fax/voice
discrimination. -
Syntax: AT-C<value>
Values: 0 Disable V.25 data calling tone to deny remote data/fax/voice discrimination.
1 Enable V.25 data calling tone to allow remote data/fax/voice discrimination.
Default: 1
Result Codes: OK if <value> = 0, 1.
ERROR if <value> ≠0, 1.

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Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434D) 20
%A Adaptive Answer Result Code Enable
Description: The %A command controls whether 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..
Syntax: AT%A<value>
Values: 0 Disables adaptive answer result codes.
1 Enables adaptive answer result codes.
Default: 0
Result Codes: OK if <value> = 0, 1.
ERROR if <value> ≠0, 1
%B View Numbers in Blacklist
Description: Blacklisting is a method of handling failed or troubled calls encountered during
automatic dialing. This command is only used to display the contents of the blacklist
when blacklisting is active. It does not affect the functionality associated with
blacklisting.
When the blacklisting option is active, use this command to display the telephone
numbers and status of any failed or troubled calls. The blacklisting option is
associated with the country selection. Some countries have national requirements
which prohibit repeat calls to the same number through automatic dialing.
Syntax: AT%B
Values: N/A
Result Codes: <list of phone numbers and their status> if country supports blacklisting.
OK if no failed calls occur.
ERROR if country selection does not support blacklisting.
%C Data Compression Control
Description: Use this command to enable or disable data compression. This command enables or
disables V.44, V.42 bis, and MNP class 5 data compression. The command
overwrites the current status of the +DCS command. The command is also
overwritten by changes made by the +DCS command. On-line changes do not take
effect until a disconnect occurs.
Syntax: AT%C<value>
Values: 0 Disable V.42bis/MNP 5. No data compression.
1 Enable V.42bis/MNP 5. Data compression enabled.
Default: 1
Result Codes: OK if <value> = 0, 1.
ERROR if <value> ≠0, 1.
%DC AT Command Control
Description: Use this command to set whether or not the modem will respond to AT commands.
Note: This command does not apply to the parallel build.
Syntax: AT%DC<value>
Values: 0 The modem responds to AT commands. The modem will respond to
AT%DC for 10 seconds after it is turned on.
1 The modem ignores AT commands.
Default: 0