AT COMMANDS

The PC or terminal communicates with the modem through the use of the AT commands. Your communication software will act as an interface between you and your modem. You read this chapter to customise your configuration.

To issue these industry-standard "AT" commands, first load a communication software package and then enter Terminal or Interactive Mode (Refer to your communication software manual).

All command lines must begin with the ASCII letters "AT" and end with "<Enter>" except for the A/ command and escape characters (default +++), which will be discussed later. The letters "AT" are sometimes referred to as an attention code. This command indicates to the modem that one or more commands are to follow. The "AT" and all following alphabetic characters may be in upper or lower case.

AT must be entered in the same case such as "AT" or "at".

"At" or "aT" are not permitted.
 

A series of commands can be grouped in a single line. The commands can be entered in a string with or without spaces for readability. Spaces within or between commands are ignored. The maximum number of characters in any command line is 39 (including ''AT"). During the entry of a command, the backspace key can be used to correct errors with the exception of "AT".

If a syntax error is found anywhere in a command line, the remainder of the line will be ignored and the ERROR result code will be returned. Most commands entered with parameters out of range will not be accepted and the ERROR result code will be returned.

This chapter lists all the commands used to configure the modem. It includes standard Hayes AT commands, Hayes V-series commands and extended commands to control ACTIVE modem.
 

DESCRIPTION OF AT COMMANDS

The symbol * means command setting may be stored in one of the two user profiles with the AT&Wn command.

A/ Re-execute command

Re-executes the most recent AT command string. The principle application of connect due to a busy line, no answer, or a wrong number. This command must appear alone in a command line and must be terminated by the "/" character. (A <Enter> should not be entered to end the command.)

+++ Escape Characters Default : +

Switch the modem from Online State to Command State without breaking the data connection. This character can be redefined by changing the value in S Register S2.

AT=x Write to Selected S Register

This command writes the value x to the currently selected S register. An S register can be selected by using the ATSn command. All of the S-register will return the OK response if x is a number.

AT? Read Selected S Register

This command reads and displays the selected S register. An S register can be selected by using the ATSn command.

ATA Answer

This must be the last command entered into the command line. The modem proceeds with the connect sequence in answer mode. The modem will enter the connect state after exchanging carrier with the remote modem. If no carrier is detected within a wait period specified in register S7(default = 50 seconds), the modem will disconnect. Any character may be entered via the DTE during the connect sequence to abort the command.

ATBn * Set ITU-T or Bell mode Default : 0

ATB0 Selects ITU-T V.22 and V.21 standards for communication at 1200 and 300bps
ATB1 Selects Bell 212A and 103 standards for communication at 1200 and 300bps

ATCn Carrier control Default : 1

This command is included for compatibility only, and has no effect other than returning a result code.
ATC1 Normal transmit carrier switching

ATDn Dial

This must be the last command in a command line. ATD causes the modem to go off-hook, dial according to the parameters entered, and attempt to establish a connection.

If there are no parameters, then the modem goes off-hook in originate mode without dialling a number.

Punctuation may be used for clarity. Parentheses, hyphens and spaces are ignored. If an invalid character is entered, that character and all subsequent characters in the dial string are ignored. The modem truncates dial strings to 36 characters.

Parameters: 0-9 A B C D * # L P T R ! @ W , ; ^ S=n

0-9   DTMF digits 0 to 9
A-D DTMF digits A,B,C and D. These digits may be prohibited in some countries
*     The "star" digit (tone dialling only)
#     The "gate" digit (tone dialling only)
J      Perform MNP 10 link negotiation at the highest supported speed for this call (Optional)
K    Enable power level adjustment during MNP 10 link negotiation for this call (Optional)
L     Dials the last dial string that was dialled
P     Use pulse dialling
T     Use DTMF dialling
R     Reverse mode. Allow the modem to call an originate-only modem by forcing the call into "answer mode".              Must be entered as the last character of the command string (optional).
!      Cause the modem to go on-hook for a time defined by the value in S29 and then off-hook.
@    Cause the modem to listen for 5 seconds of silence
W   Wait up to the period of time specified in register S7 for dial tone before dialling
,      Pause for the value specified by register S8 during dial
;      Return to Command State after dialling
^     Turn on calling tone
()     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
S=    n Dial number previously stored in directory location n using AT&Zn command

ATE * Command echo Default : 1

ATE0 Inhibits the echoing of commands
ATE1 Enables the echoing of commands

ATHn Switch-hook control Default : 0

ATH0 Cause the modem to go on-hook
ATH1 If modem is on-hook, modem goes off-hook, returns an OK response, and waits for further commands

ATIn Identification

I0 Reports product code
I1 Reports pre-computed checksum from ROM
I2 Computes checksum and compares it with value stored in ROM. Reports result as OK or ERROR.
I3 Reports firmware revision
I4 Reports OEM defined identifier string
I5 Reports Country Code parameter
I6 Reports firmware revision
I7 Reports modem data pump model

ATLn * Speaker volume Default : 2

ATL0 Selects low speaker volume
ATL1 Selects low speaker volume
ATL2 Selects medium speaker volume
ATL3 Selects high speaker volume

ATMn * Speaker control Default : 1

ATM0 Speaker is always off
ATM1 Speaker is on during handshaking in call establishment but is turned off while the modem is receiving a carrier signal from a remote modem
ATM2 Speaker is always on
ATM3 Speaker goes off while the modem is receiving a carrier signal from a remote modem and while the modem is dialling. However, speaker is on during answering

ATNn * Modulation handshake Default : 1

ATN0 Requires the speed of the connection be that specified by the value held in S37; if S37=0, the speed of the connection must match that at which the last AT command was issued. If the selected speed can be achieved using more than one communication standard (e.g., Bell 212A or ITU-T V.22 at 1200bps), the modem also refers the selection made with the ATB command

ATN1 Permits handshaking to occur at any speed supported by both modems. Enables automode detection. The ATB command is ignored in this mode and the modem attempts only ITU-T mode connections.

ATOn Return to the on-line state Default : 0

ATO0 Causes the modem to return to the data mode
ATO1 Causes the modem to return to the data mode and to initiate a retrain

ATP * Set pulse dial as default

ATQn * Result code display Default : 0

ATQ0 Allows the modem to send result codes to the DTE
ATQ1 Prohibits the modem from sending result codes to the DTE

ATSn Establish S register n as the default register

ATSn? Reading S registers

Reads the contents of the S register. All the S registers may be read.

ATSn=x Writing to S registers

Writes the value of x to the specified S register n
 

ATT * Set tone dial as default

ATVn * Result code form (message control) Default : 1

ATV0 Allows short form (numeric) result codes to be sent
ATV1 Allows long form (verbose) result codes to be sent
 

ATWn * Negotiation progress reporting Default : 0

ATW0 Error-correction call progress not reported
ATW1 Error-correction call progress reported
ATW2 Error-correction call progress not reported. CONNECT XXXX message reports DCE speed.
 

ATXn * Extended result codes Default : 4

ATX0 Modem ignores dial tone and busy signal. Sends CONNECT message when a connection is established by blind dialling
ATX1 Modem ignores dial tone and busy signal. Sends CONNECT XXXX message reflecting bit rate when a connection is established by blind dialling
ATX2 Modem ignores busy signal but waits for dial tone before dialling. If dial tone is not detected within 5 seconds, the NO DIAL TONE message is sent. Sends CONNECT XXXX message reflecting bit rate when a connection is established.
ATX3 Modem ignores dial tone. Sends BUSY message if a busy signal is detected. Sends CONNECT XXXX message reflecting bit rate when a connection is established by blind dialling.
ATX4 If dial tone is not detected within 5 seconds, sends NO DIAL TONE message. If busy signal is detected, sends BUSY message. Sends CONNECT XXXX message reflecting bit rate when a connection is established.
 

ATYn * Control long space disconnect Default : 0

ATY0 Disables long space disconnect
ATY1 Enables long space disconnect
 

ATZn Reset Default : 0

Restore the active configuration with the user profile
ATZ0 Soft reset and restore stored profile 0
ATZ1 Soft reset and restore stored profile 1

AT&An * Handshake Abort Option Default : 1
 

AT&A0 Disables the user abort during handshaking. Once the dialling string is entered or answer is initiated, the handshaking cannot be aborted. Only dropping DTR signal (except &D0 option) and pressing T/D switch can abort the operation.
AT&A1 Enables the user abort during handshaking. Anytime during
a handshaking sequence, the call and answer can be aborted by receiving any character from DTE.
 

AT&Cn * RS232-C DCD option Default : 1

AT&C0 DCD is ON regardless of the state of the data carrier from the remote modem
AT&C1 DCD follows the state of the data carrier from the remote modem
 

AT&Dn * RS232-C DTR option Default : 2

Determines actions taken by the modem in relation to the DTR signal of the serial port.
The action for the event that follows DTR drop indicated in the following table:

 

1 Modem disconnects and sends OK result code
2 Modem goes into command mode if in data mode and sends the OK result code
3 Modem disconnects, sends the OK result code, and disables auto answer while DTR is off
4 Modem performs a warm start (i.e., same as ATZ command)

AT&Fn Restore factory configuration Default : 0

&F0 Recalls factory default as V.42bis auto-reliable mode
&F1 Recalls factory default as MNP 5 auto-reliable mode
&F2 Recalls factory default as DIRECT mode

AT&Gn * Set guard tone Default : 0

AT&G0 No guard tone
AT&G1 550 Hz guard tone
AT&G2 1800 Hz guard tone

AT&Jn * Telephone jack selection Default : 0

This command is only included for compatibility and performs no function.
AT&J0 Performs no function
AT&J1 Performs no function

AT&Kn * DTE/modem flow control Default : 3

AT&K0 Disables flow control
AT&K3 Enables RTS/CTS flow control
AT&K4 Enables XON/XOFF flow control
AT&K5 Enables transparent XON/XOFF flow control
AT&K6 Enables both RTS/CTS and XON/XOFF flow control (Default for fax mode)

AT&Ln * Transmission line type Default : 0

AT&L0 Dial-up line
AT&L1 2-wire Leased line (Option)
AT&L2 4-wire Leased line(Option)

AT&Mn * Communication mode
        Same as AT&Q0-3

AT&Pn * Dial pulse ratio Default : 0

AT&P0 39%/61% make/break ratio @ 10pps
AT&P1 33%/67% make/break ratio @ 10pps
AT&P2 39%/61% make/break ratio @ 20pps
AT&P3 33%/67% make/break ratio @ 20pps

AT&Qn * Communication mode Default : 5

AT&Q0 Selects direct asynchronous operation
AT&Q1 Selects synchronous mode 1 operation
AT&Q2 Selects synchronous mode 2 operation
AT&Q3 Selects synchronous mode 3 operation
AT&Q4 Selects autosync operation
AT&Q5 Selects error correction mode
AT&Q6 Selects asynchronous operation in normal mode

AT&Rn * RS232-C RTS/CTS option Default : 0

AT&R0 CTS tracks RTS, CTS is turned ON in response to an OFF-to-ON transition of RTS from the local DTE after a delay period specified by register S26 in increments of 10 milliseconds.

AT&R1 The modem ignores RTS, CTS is held ON unless AT&K3 has been selected

AT&Sn * RS232-C DSR option Default : 0

AT&S0 DSR is always ON
AT&S1 DSR operates in accordance with the EIA-232-C specification

AT&Tn * Test and diagnostic Default : 4

A test can be run only when in an asynchronous operation in non-error correction mode (normal or direct mode). To terminate a test in progress, the escape sequence must be entered first, except for parameters 7 and 8. If S18 is non-zero, a test will terminate automatically after the time specified by S18 and display the OK message.

AT&T0 Ends test in progress
AT&T1 Initiates local analog loopback
AT&T3 Initiates remote digital loopback locally. If no connection exists, ERROR is returned.
AT&T4 Allows the modem to respond to a request from a remote modem for a remote digital loopback test
AT&T5 Prohibits the modem from granting a request from a remote modem for a remote digital loopback test
AT&T6 Initiates remote digital loopback. If no connection exists, ERROR is returned.
AT&T7 Initiates remote digital loopback with self test. If no connection exists, ERROR is returned.
AT&T8 Initiates local analog loopback with self test

AT&V View current configuration and user profiles / last connection statistics

AT&V0 Displays the active configuration and user profiles
AT&V1 Displays the last connection statistics

AT&Wn Store user profile Default : 0

AT&W0 Save as user profile 0
AT&W1 Save as user profile 1

AT&Xn * Clock source selection Default : 0

Select the source of the transmit clock for the synchronous operation. In asynchronous mode, the transmit and receive clock are turned OFF.
AT&X0 Selects internal timing. The modem generates the transmit clock signal and applies it to TXCLK output (Pin 15 of RS232-C) at the serial interface

AT&X1 Selects external timing. The local DTE sources the transmit clock signal on the XTCLK input (Pin 24 of RS232-C) of the serial interface. The modem applies this clock to TXCLK output (Pin 15 of RS232-C) at the serial interface.

AT&X2 Selects slave receive timing. The modem derives the transmit clock signal from the incoming carrier and applies it to the TXCLK output (Pin 15 of RS232-C) at the serial interface.

AT&Yn * Designate default user profile Default : 0

Selects which user profile will be used after a hard reset.
AT&Y0 Selects user profile 0
AT&Y1 Selects user profile 1

AT&Zn=x Store phone number (n = 0 - 3) Default : 0
        Stores a 36-digit dial string (x) in the specified entry (n) for later dialling (see ATDS=n command).

AT\An Maximum MNP block size Default : 2

AT\A0 Sets maximum block size to 64 characters
AT\A1 Sets maximum block size to 128 characters
AT\A2 Sets maximum block size to 192 characters
AT\A3 Sets maximum block size to 256 characters

AT\Bn Transmit break (n=1-9) Default : 3

When this command is entered during a non-MNP connection, the modem sends a break signal to the remote modem. The length of the break is 100 times the n parameter value in milliseconds. If this command is entered in MNP mode, the modem sends a link attention PDU to the remote modem.

AT\Gn Modem to modem flow control Default : 0

AT\G0 Disables flow control (XON/XOFF)
AT\G1 Enables flow control (XON/XOFF)

AT\Jn Enable DTE auto Rate Adjustment Default : 0

\J0 Disables adjustment of DTE speed to match line speed
\J1 Enables adjustment of DTE speed to match line speed

AT\Kn Break control Default : 5

When a break is received from the DTE during data transfer, the modem responds as follows:
AT\K0,2,4 Modem enters the online Command State without sending a break to the remote modem
AT\K1 Modem clears the terminal and modem buffers and sends a break to the remote modem
AT\K3 Modem does not clear the buffers but sends a break to the remote modem
AT\K5 Modem sends a break to the remote modem in sequence with any transmitted data
When the modem is in the online Command State during a data connection, the modem takes the following actions:
AT\K0,1 Modem clears the terminal buffers and sends a break to the remote modem
AT\K2,3 Modem does not clear buffers but sends a break to the remote modem
AT\K4,5 Modem sends a break in sequence with any transmitted data
When a break is received from the DTE during a non-error correction mode, the modem takes the following action:
AT\K0,1 Modem clears the terminal buffers and sends a break to the local DTE
AT\K2,3 Modem does not clear buffers but sends a break to the local DTE
AT\K4,5 Modem sends a break in sequence with any received data

AT\Ln MNP block transfer control Default : 0

AT\L0 Uses stream mode for MNP link connections
AT\L1 Uses block mode for MNP link connections

AT\Nn Operation mode control Default : 3

\N0 Selects normal speed buffered mode (no error correction)
\N1 Selects direct mode (equivalent to &M0, &Q0)
\N2 Selects reliable mode. Failure to make reliable connection results in the modem hanging-up
\N3 Selects auto-reliable mode
\N4 Selects LAPM error correction mode. Failure to make an LAPM error correction connection results in the modem hanging-up
\N5 Selects MNP error correction mode. Failure to make an MNP error correction connection results in the modem hanging-up

AT\Vn Connect Message Default : 0

AT\V0 Disable single line connect message.
AT\V1 Enable single line connect message

AT%Cn * Compression control Default : 3

%C0 Disables data compression
%C1 Enables MNP5 data compression
%C2 Enables V.42bis data compression
%C3 Enables both MNP5 and V.42bis data compression

AT%En Enable/disable auto-retrain Default : 2

Controls whether 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)
%E0 Disables line quality monitor and auto-retrain
%E1 Enables line quality monitor and auto-retrain
%E2 Enables line quality monitor and fallback/fall forward
%E3 Enables line quality monitor and auto-retrain, but hang-up immediately when EQM reaches hang-up threshold (fast hang-up)

AT%L Report received signal level

Returns a value identifying the received signal level. The value is implemented as follows:
001 = Received level of -1dBm
002 = Received level of -2dBm
. .        . .
 43    Received level of -43dBm

AT%On * Selects answer/originate mode Default : 1

%O0 Selects answer mode
%O1 Selects originate mdoe

AT%Rn * Selects receive sensitivity (336RL ,336RL4 models) Default : 0

%R0 -43dBm
%R1 -33dBm

(For 336RD cards, use on board jumper JP2 to select receive sensitivity
JP2  1-2 shorted : -33dBm
        2-3 shorted : -43dBm )

AT%Q Report line signal quality

Returns the high-order byte of the calculated Eye Quality Monitor(EQM) value. The high-order byte can range from 0 to 127. However, when the value is 70DC ±10 (depending on the line speed) or greater, the modem will automatically retrain if enabled by the AT%E1 command. The value for a normal connection ranges from about 0 to 15 and approaches 60 for a progressively poorer connection.

AT#CIDn Caller ID Default : 0

AT#CID=0 Disables Caller ID
AT#CID=1 Enables Caller ID with formatted presentation to the DTE
AT#CID=2 Enables Caller ID with unformatted presentation to the DTE
AT#CID? Retrieves the current Caller ID mode from the modem
AT#CID=? Returns the mode capabilities of the modem in a list with each element separated by commas

AT-SDR=n Enable/Disable Distinctive Ring Default : 0

AT-SDR=0 Disable Distinctive Ring. Any valid ring detected is reported as RING
AT-SDR=1 Enable Distinctive Ring Type 1.
AT-SDR=2 Enable Distinctive Ring Type 2.
AT-SDR=3 Enable Distinctive Ring Type 1 and 2.
AT-SDR=4 Enable Distinctive Ring Type 3.
AT-SDR=5 Enable Distinctive Ring Type 1 and 3.
AT-SDR=6 Enable Distinctive Ring Type 2 and 3.
AT-SDR=7 Enable Distinctive Ring Type 1,2,3.

 
AT+MS * Select Line Modulation

The command format is : (336 models)
AT+MS=<mod>,<automode>,<min_rate>,<max_rate>

Default value is +MS=11,1,300,33600 (336 models only)

The command format is : (560 models)
AT+MS=<mod>,<automode>,<min_rate>,<max_rate>,<x_law>,<rb_si

gnal>, <Maxup_rate>
Default value is +MS=12,1,300,56000,0,0,33600(560 models only)
AT+MS?

send a string of information to the DTE consisting of selected options.

AT+MS=?

send a string of information to the DTE consisting of supported options.

 

 
<x_law> is an optional number which specifies the codec type. The options are:

0 = u-Law

1 = A-Law

Note that ATZ will reset the <x_law> selection to 0 (u-Law)

<rb_signaling> is an optional number which enables or disable robbed bit signaling generation in a server modem or enables or disables robbed bit signaling detection in a client modem. The option are:

0 = Robbed bit signaling generation (server modem) or detection (client modem) disable.

1 = Robbed bit signaling generation (server modem) or detection (client modem) enabled.

Note that ATZ will reset the <rb_signaling> selection to 0.

Maxup_rate : The max value for this field is 33600.
 

 

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AT COMMANDS for Synchronous Configuration.

AT&Xn Clock source selection Default : 0

Select the source of the transmit clock for the synchronous operation. In asynchronous mode, the transmit and receive clock are turned OFF.
AT&X0 Selects internal timing. The modem generates the transmit clock signal and applies it to TXCLK output (Pin 15 of RS232-C) at the serial interface

AT&X1 Selects external timing. The local DTE sources the transmit clock signal on the XTCLK input (Pin 24 of RS232-C) of the serial interface. The modem applies this clock to TXCLK output (Pin 15 of RS232-C) at the serial interface.

AT&X2 Selects slave receive timing. The modem derives the transmit clock signal from the incoming carrier and applies it to the TXCLK output (Pin 15 of RS232-C) at the serial interface.

AT&Qn Communication mode Default : 5

AT&Q0 Selects direct asynchronous operation
AT&Q1 Selects synchronous mode 1 operation
AT&Q2 Selects synchronous mode 2 operation
AT&Q3 Selects synchronous mode 3 operation
AT&Q4 Selects autosync operation
AT&Q5 Selects error correction mode
AT&Q6 Selects asynchronous operation in normal mode

AT COMMAND for Leased Line Configuration

AT%On * Selects answer/originate mode Default : 1
        %O0 Selects answer mode
        %O1 Selects originate mode

AT&Ln * Transmission line type Default : 0
        AT&L0 Dial-up line
        AT&L1 2-wire Leased line (Option)
        AT&L2 4-wire Leased line(Option)