Modem commands

This section provides information on the AT modem commands in case you need to operate your modem from terminal software.

Running commands

Your modem is in command mode at power-on and is ready to receive and run AT commands. The modem remains in command mode until it connects with a remote modem. Commands might be sent to the modem from an attached terminal or a PC running a communication program.

The modem is designed to operate at common DTE speeds ranging from 115.2 Kbps (or 57.6 Kbps) to 300 Kbps. All commands and data must be issued to the modem using one of the valid DTE speeds.

Command format

All commands (except A/) must begin with the AT prefix, followed by the command letter and ended with the Enter key. Spaces are allowed in the command string to increase command readability but are ignored by the modem during command execution. All commands might be typed in either uppercase or lowercase, but not mixed. A command issued without a parameter is considered as specifying the same command with a parameter "0".

Example:

ATL[Enter]

This command causes your modem to lower its speaker volume.

AT commands

Command  Function  
+++  Escape sequence:
Exit data mode and enter online command mode.  
A/  Repeat last command:
Repeat the preceding command.

Note: Do not precede with AT or follow with Enter.  

A  Answer command:
Answer an incoming call.  
Bn  Communication standard setting:
Determine the standard.
 B0: Select ITU/CCITT V.22 mode @ 1200 bps.
 B1: Select BELL 212A @ 1200 bps. (default).
 B2: Deselect V23 reverse channel (same as B3).
 B3: Deselect V23 reverse channel (same as B2).
 B15: Select ITU/CCITT V.21mode @ 300 bps.
 B16: Select BELL 103J mode @ 300 bps.
 
Cn  Carrier control:
C0: Transmit carrier always off.
C1: Normal transmit carrier switching.
 
Dsn  Dial a telephone number n (n=0-9, A-D, #, and *) automatically. You can also assign the following:
s = L Redial the last number dialed.
s = P Specify pulse dial.
s = T Specify tone dial (default).
s = W Wait for a second dial tone.
s = , Pause.
s = @ Wait for 5 seconds of silence.
s = ! Specify flash.
s = ; Return to command mode after dialing.
s = $ Detect a bong tone.
 
DS=n  Dial command:
Dial one of four stored telephone numbers (n=0-3) in the modem's nonvolatile memory.  
En  Echo command:
E0: Disable echo to the computer.
E1: Enable echo to the computer (default).
 
Fn  Online data character echo command:
Determine if the modem will echo data from the DTE.
F0: Online data character echo enabled (not supported).
F1: Online data character echo disabled.
 
Hn  Hook control:
Control on-hook/off-hook.
H0: Modem goes on-hook (default).
H1: Modem goes off-hook.
 
I  Request ID information:
Display specific product information about the modem.
I0: Specify the firmware and device ID.
I1: Specify the checksum code.
I2: Start the ROM test and verify the checksum.
I3: Specify the firmware and device ID (same as I0).
I4: Specify the firmware version for data pump.
I5: Specify the code version, board ID, country ID, and subsystem vendor ID in hexadecimal.
I6-8: Return OK for compatibility.
I9: Specify the country ID in English.
I11: Display connection information.
 
L  Set the speaker volume.
L0: Select low volume.
L1: Select low volume.
L2: Select medium volume (default).
L3: Select high volume.
 
M  Control the speaker mode.
M0: Turn the speaker off.
M1: Turn the speaker on until the modem detects the carrier signal (default).
M2: Keep the speaker on when the modem is off-hook.
M3: Keep the speaker on until the carrier is detected, except when dialing.
 
N  Modulation handshake:
Control whether the local modem performs a negotiated handshake.
N0: Disable auto mode, with the modem handshake speed specified by S37.

N1: Enable auto mode, with the modem handshake speed specified by S37 (default).
 
O  Return to online data mode.
O0: Return to data mode.
O1: Start an equalizer retain, and return to data mode.
O3: Start a rate renegotiation, and return to data mode.
 
P  Select pulse dialing.  
Q  Turn the result code on or off:
Q0: Enable result codes (default).
Q1: Disable result codes.
 
Sn  Control the S register.
Sn?: Read S register n where n=0-110.
Sn=r: Set the S register n to value r (n=0-110, r=0-255)
 
T  Select tone dialing.  
V  DCE response format:
Control the result code format.
V0: Display the result code as digits.
V1: Display the result code as text (default).
 
W  Result code options:
W0: The CONNECT result code reports the DTE receive speed. Disable protocol result codes.

W1: The CONNECT result code reports the DTE receive speed. Enable protocol result codes.

W2: The CONNECT result code reports the DCE receive speed. Enable protocol result codes (default).
 
X  Result code selection and call progress monitoring:
Control tone detection option used in the dialing process. 
      Extended       Dial           Busy
    result code    tone detect    tone detect
 X0   Disable        Disable        Disable
 X1   Enable         Disable        Disable
 X2   Enable         Enable         Disable
 X3   Enable         Disable        Enable
 X4   Enable         Enable         Enable (default)
 X5   Enable         Enable         Enable
 X6   Enable         Enable         Enable
 X7   Disable        Enable         Enable
 
Y  Keep long space disconnect disabled.
Y0: Disable long space disconnect (default).
Y1: Enable long space disconnect (not supported).
 
Z  Reset and recall the stored profile.  

Extended AT commands


Command  Function  
&B  V.32 auto-retrain:
This modem always auto-retrains.
&B0: Disable V.32 auto-retrain (not supported).
&B1: Enable V.32 auto-retrain (default).
 
&C  Data carrier detect (DCD) control:
&C0: Specify that carrier detect is always on.
&C1: Turn on the carrier detect when the remote carrier is present (default).
 
&D  Data terminal ready (DTR):
&D0: Ignore the DTR signal.
&D1: Return the modem to command mode after a DTR toggle.
&D2: Hang up the modem, and return to command mode after a DTR toggle (default).
&D3: Reset the modem after a DTR toggle.
 
&F  Local factory settings:
Load the factory default configuration.  
&G  V.22bis guard tone control:
Determine which guard tone to transmit while transmitting in the high band.
&G0: Disable the guard tone (default).
&G1: Enable a 550-Hz guard tone.
&G2: Enable a 1800-Hz guard tone.
 
&J  Auxiliary relay option:
&J0: The auxiliary relay is never closed (default).
&J1: Not supported.
 
&K  Local flow control selection:
&K0: Disable flow control.
&K1: Reserved.
&K2: Reserved.
&K3: Enable RTS/CTS (hardware) flow control (default).
&K4: Enable XON/XOFF flow control.
 
&M  Asynchronous communications mode:
&M0: Asynchronous mode (default).
&M1: Reserved.
&M2: Reserved.
&M3: Reserved.
&M4: Reserved.
 
&Pn  Pulse dial make-to-break ratio selection:
This command is effective only for Japan.
&P0: 39/61 make/break ratio, 10PPS.
&P1: 33/67 make/break ratio, 10PPS (default).
&P2: 33/67 make/break ratio, 20PPS.
 
&Q  Asynchronous communication mode:
&Q0: Asynchronous mode, buffered. Same as \N0.
&Q5: Error Control Mode, buffered (default). Same as \N3.
&Q6: Asynchronous mode, buffered. Same as \No.
&Q8: MNP error control mode.
If an MNP error control protocol is not established, the modem will fall back according to the current user setting in S36.
&Q9: V.42 or MNP error control mode.
If neither error control protocol is established, the modem will fall back according to the current user setting in S36.
 
&S  Data set ready (DSR) option:
This command selects the DSR action.
&S0: DSR always ON (default).
&S1: DSR comes on when establishing a connection and goes off when the connection ends.
 
&T  Self-test commands:
Do diagnostic tests on the modem.
&T0: Abort. Stop any test in progress.
&T1: Local analog loop.
&T3: Local digital loopback test.
&T6: Remote digital loopback test.
 
&V  View the active configuration.
This command is used to display the active profiles.  
&W  Store current configuration.
Store certain command options and S-register values except S3, S4, S5.  
&Y  Select the stored profile for hard reset
(for compatibility with applications that issue the &Y0 command).
&Y0: Select stored profile 0 on power-up.
&Y1: Error.
 
&Z  Store the telephone number:
Store up to 4 digits in a dialing string.  
\A  Select the maximum MNP block size.
\A0: 64 characters.
\A1: 128 characters.
\A2: 192 characters.
\A3: 256 characters.
 
\B  Transmit break to remote.
\Bn: Break length in 100ms units (n=1-9, default: 3).
 
\G  Modem port flow control:
\G0: Modem process XON/XOFF flow control characters locally (default).
\G1: Modem process XON/XOFF flow control characters.
 
\J  Adjust bit/s rate control.
\J0: Buffer mode. Error control selected by \Nn command (default).
\J1: Force the maximum DCE rate to the DTE rate.
 
\K  Send break control:
[a] If the modem receives a break from the DTE while the modem is operating in data transfer mode:
\K0: Enter online command mode, no break send to the remote modem.
\K1: Clear data buffers and send a break to the remote modem.
\K2: Same as 0.
\K3: Send a break to the remote modem immediately.
\K4: Same as 0.
\K5: Send a break to the remote modem in sequence with transmitted data (default).
[b] If the modem is in the online command state during a data connection, and \B is received to send a break to the remote modem:
\K0: Clear data buffers and send a break to the remote modem.
\K1: Clear data buffers and send a break to the remote modem (same as 0).
\K2: Send a break to the remote modem immediately.
\K3: Send a break to the remote modem immediately (same as 2).
\K4: Send a break to the remote modem in sequence with data.
\K5: Send a break to the remote modem in sequence with data (same as 4) (default).
[c] If a break is received from a remote modem during a connection:
\K0: Clear data buffers and send a break to the DTE.
\K1: Clear data buffers and send a break to the DTE (same as 0).
\K2: Send a break to the remote modem immediately.
\K3: Send a break to the remote modem immediately (same as 1).
\K4: Send a break in sequence with received data to DTE.
\K5: Send a break in sequence with received data to DTE (same as 4) (default).
 
\N  Error control mode selection:
\N0: Buffer mode. No error control (same as &Q6).
\N1: Direct mode.
\N2: MNP or disconnect mode.
\N3: V.42, MNP, or buffer (default).
\N4: V.42 or disconnect.
\N5: V.42, MNP, or buffer (same as \N3).
\N7: V.42, MNP, or buffer (same as \N3).
 
\Q  Local flow control selection:
\Q0: Disable flow control. Same as &K0.
\Q1: XON/XOFF software control. Same as &K4.
\Q2: CTS-only flow control. This is not supported, and the response is error.
\Q3: RTS/CTS to DTE (default). Same as &K3.
 
\R  Ring indicator off after answer:
\R0: The ring indicator signal is off after the telephone is answered.
 
\T  Inactivity timer:
\T0: Inactivity timer disabled (default).
\Tn: Inactivity timer, n minutes. (n=1-255)
 
\V  Protocol result code:
\V0: Disable the protocol result code appended to the DCE speed.
\V1: Enable the protocol result code appended to the DCE speed (default).
\V2: Same as \V1.
 
\X  XON/XOFF passthrough:
\X0: Specify that the modem process XON/XOFF flow control characters locally (default).
\X1: Specify that the modem passes XON/XOFF flow control characters.
 
%B  View numbers in the blacklist:
Displays the numbers for which the last call attempted in the past 2 hours failed.  
%C  Data compression control:
%C0: V.42bis/MNP5 disabled. No data compression.
%C1: V.42bis/MNP5 enabled. Data compression enabled (default).
 
%E  Automatic rate change:
%E0: Disable fall back and fall forward.
%E1: Enable fall back, but disable fall forward.
%E2: Enable fall back and fall forward (default).
 
-C  Data calling tone:
-C0: Disabled (default).
-C1: Enabled.
 
-V90  Enable or disable the V.90 setting:
-V90=0: Disable V.90.
-V90=1: Enable V.90 auto rate (default).
-V90=n: Control the downstream rate (2-23).
-V90=?: Show the range of n.
-V90?: Show the current value.