Hayes AT Command Quick Reference
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ISSUING COMMANDS TO YOUR MODEM
==============================
Your modem is always in either command mode or online mode. The modem
starts up in command mode when it is turned on. Commands are only
accepted by the modem in command mode. When connection to a remote
system is established, your modem is in online mode. Commands entered
while the modem is in on-line mode are treated as data, not as commands.
Command Line Prefix
-------------------
The AT prefix (also known as the ATtention Code) alerts the modem that
one or more commands are to follow. The letters AT-the command line
prefix-can be typed as either uppercase or lowercase characters. Both
the A and T, however, must be in the same case.
All commands, except two, must begin with the characters AT and end with
a carriage return. The two exceptions are the escape sequence (+++) and
the repeat command (A/). The carriage return character is produced when
you press Enter.
The modem stores your command line in a 255-character buffer. The AT
prefix, the carriage return, and the linefeed characters (if any) do not
go into the buffer and are not included as part of the character
limitation. Spaces added between commands are not included as part of
the total. If you attempt to put more than 255 characters in the buffer,
an ERROR result code will be sent by the modem, and the command line
will be ignored.
Note: If your monitor screen displays AATT instead of AT, you may disable
the command echo feature by typing in the ATE0 (zero) command.
Resetting the Modem
-------------------
The ATZ command resets the modem to the configuration profile stored in
nonvolatile memory location 0. The ATZ1 command resets the modem to the
configuration profile stored in non-volatile memory location 1.
Dialing with AT Commands
------------------------
To dial the modem with AT commands, type ATDT 9 W 555-1234.
This command means (AT)tention modem, (D)ial using
(T)one dialing, dial a 9 to access an outside line, (W)ait for a dial
tone, dial 5551234 and wait for an answer.
Saving a Phone Number
---------------------
To save a phone number, type AT&Z1=T9 W 555-1234.
This command line causes the modem to store T9W5551234 in telephone
number location 1 of nonvolatile memory.
There are four locations set aside in the modem’s nonvolatile memory in
which you can store frequently-dialed telephone numbers or other often-
used numerical sequences.
The modem transfers the number stored in the specified telephone number
location to the command buffer-as if you typed it from the keyboard. The
command to dial a stored number is issued in the form:
Dialing a Saved a Phone Number
------------------------------
To dial a saved phone number, type ATDS=1.
The above command dials the numerical sequence found in the telephone
number storage location 1 of nonvolatile memory.
Redialing the Last Number
-------------------------
The ATDL command allows you to have the modem redial the last number
called during the current session. Although the numbers or dial strings
stored with the AT&Zn=x command remain in memory from one session to the
next, numbers used by the ATDL command do not.
Automatic Answering
-------------------
The modem can be set to pick up the telephone automatically after a
predetermined number of rings. To set the modem to answer the telephone
after n rings, type ATS0=n.
The variable n is a value between 1 and 255.
You can turn off the auto answer function with the command ATS0=0.
AT COMMANDS
===========
Your modem supports the Hayes Standard AT Command Set, S-registers, and
result codes common to most modems. Below is a quick reference which list
the commands your modem supports. Entries marked with an asterisk are the
factory-set default commands. If you issue a command that is not applicable,
the ERROR result code will be returned.
Command Description
------- -----------
+++ Escape Sequence. Used to switch from command to online mode.
A Answer immediately without waiting for ring.
A/ Repeat last command.
This command is not prefixed by AT or followed by a return.
B0 Initiate calls using ITU-T V.22 at 300 or 1200 bps.
B1 Initiate calls using 212A at 300 or 1200 bps.
D Dial.
Modifier Description
-------- ------------
T Dial using Tone method.
P Dial using Pulse method.
L Last number redial.
, Pause before continuing the dial string.
W Wait for second dial tone.
@ Wait for quiet answer.
! Issue hookflash.
; Return to command mode after dialing.
S=n Dial telephone number n (0-3) stored with &Zn=x.
E0 Do not echo characters to the screen in command mode.
E1 Echo characters from the keyboard to the screen in command mode.
H0 Hang up.
H1 Pick up phone line.
I0 Display product number.
I1 Displays pre-computed checksum from ROM.
I2 Performs ROM checksum test (OK or ERROR).
I3 Display the firmware revision number.
I4 Display version bit map for software modem identification.
L0, L1 Set low speaker volume.
L2 Set medium speaker volume.
L3 Set high speaker volume.
M0 Turn speaker off.
M1 Turn speaker on until carrier is detected.
M2 Turn speaker on.
M3 Turn speaker off until carrier detected, turn on when answering.
O0 Go to online mode.
O1 Go to online mode and retrain.
Q0 Return result codes.
Q1 Do not return result codes.
Sr? Read and respond with current value of register r.
Sr=n Set the value of register r to value n.
V0 Display result codes as numbers.
V1 Display result codes as words.
W0 Do not return negotiation progress messages.
W1 Return negotiation progress messages.
W2 Do not return negotiation progress messages and return CONNECT
messages using modem-to-modem (DCE) speeds.
X0 Provide basic call progress result codes: CONNECT, NO CARRIER, RING,
OK, ERROR, and NO ANSWER.
X1 Provide basic call progress result codes and appropriate connection
speed (e.g., CONNECT 1200, CONNECT 2400).
X2 Provide basic call progress result codes, connection speed, and
DIALTONE detection.
X3 Provide basic call progress result codes, connection speed, and
BUSY signal detection.
X4 Provide basic call progress result codes, connection speed, BUSY
signal detection, and DIALTONE detection.
Z0 Reset and recall stored user profile 0.
&C0 Assume presence of carrier detect signal.
&C1 Track presence of carrier detect signal.
&D0 Ignore status of DTR signal.
&D1 Monitor DTR signal. When an on-to-off transition of DTR signal
occurs, enter the command mode. Return to the online mode when the
O0 command is issued (if the connection has not been broken).
&D2 When an on-to-off transition of DTR signal occurs, hang up and
enter the command mode.
&D3 When an on-to-off transition of DTR signal occurs, hang up and reset.
&F Recall factory configuration.
&K0 Disable local flow control.
&K3 Enable RTS/CTS local flow control.
&K4 Enable XON/XOFF local flow control.
&Q0 Communicate in asynchronous mode.
&Q5 Communicate in error-control mode.
&S0 Assert DSR signal always.
&V View active configuration, user profiles, and stored
telephone numbers.
&W0 Write current configuration to profile 0.
&Y0 Select stored user profile 0 as power-up configuration.
&Zn=x Store phone number x in location n (n=0-3).
RESULT CODES
============
Number Word Description
------ ---- -----------
0 OK Command executed.
1 CONNECT A 300 bps connection has been established.
2 RING Ring signal indicated.
3 NO CARRIER Carrier signal not detected, or lost, or inactivity
for a period of time set in the automatic timeout
register (set with S30) caused the modem to hang up.
4 ERROR Invalid command, checksum, error in command line or
command line exceeds 255 characters.
5 CONNECT Connection at 1200 bps (disabled by X0).
6 NO DIALTONE No dial tone detected. Enabled by X2 or
X4, or W dial modifier.
7 BUSY Engaged (busy) signal detected. Enabled by X3 or X4.
8 NO ANSWER No silence detected when dialing a system not
providing a dial tone. Enabled by @ dial modifier.
10 CONNECT 2400 Connection at 2400 bps.
11 CONNECT 4800 Connection at 4800 bps.
24 CONNECT 7200 Connection at 7200 bps.
12 CONNECT 9600 Connection at 9600 bps.
13 CONNECT 14400 Connection at 14400 bps.
14 CONNECT 19200 Connection at 19200 bps.
28 CONNECT 38400 Connection at 38400 bps.
18 CONNECT 57600 Connection at 57600 bps.
33 FAX FAX connection.
35 DATA DATA connection.
40 CARRIER 300 Carrier detected at 300 bps.
46 CARRIER 1200 Carrier detected at 1200 bps.
47 CARRIER 2400 Carrier detected at 2400 bps.
48 CARRIER 4800 Carrier detected at 4800 bps.
49 CARRIER 7200 Carrier detected at 7200 bps.
50 CARRIER 9600 Carrier detected at 9600 bps.
51 CARRIER 12000 Carrier detected at 12000 bps.
52 CARRIER 14400 Carrier detected at 14400 bps.
53 CARRIER 16800 Carrier detected at 16800 bps.
54 CARRIER 19200 Carrier detected at 19200 bps.
38 CARRIER 21600 Carrier detected at 21600 bps.
37 CARRIER 24000 Carrier detected at 24000 bps.
36 CARRIER 26400 Carrier detected at 26400 bps.
55 CARRIER 28800 Carrier detected at 28800 bps.
15 CONNECT 28800 Connection at 28800 bps.
66 COMPRESSION: CLASS 5 MNP5 compression negotiated.
67 COMPRESSION: V.42bis V.42bis compression negotiated.
69 COMPRESSION: NONE No compression negotiated.
70 PROTOCOL: NONE Asynchronous mode.
77 PROTOCOL: LAPM V.42 LAPM.
80 PROTOCOL: ALT Alternative protocol (MNP compatible).
S-REGISTERS
===========
S-registers are special memory locations in the modem for storing
specific configuration and operating parameters. S-registers typically
hold some type of counting, timing, ASCII character, or feature
negotiation value.S-registers can be adjusted to configure the modem
from the range of values indicated in the Range/Units column in the
following chart. Values assigned to these registers (except S1, S3, S4,
S5, S48, and S82) can be stored in user-defined profiles with the &W
command. Sr=n is the command to change an S-register (for example ATSr=n
where r is the S-register to be changed, and n is the value to be assigned
to the S-register). Sr? is the command to read the value currently stored
in an S-register (for example ATSr? where r is the S-register to be read).
Register Description Range/Units Default
-------- ----------- ----------- -------
S0 Select ring to answer on 0-255 rings 0
S1 Ring count 0-255 rings 0
S2 Escape sequence character 0-127 ASCII 43
S3 Carriage return character 0-127 ASCII 13
S4 Line feed character 0-127 ASCII 10
S5 Back space character 0-32,127 ASCII 8
S6 Wait before blind dialing 2-255 sec 2
S7 Wait time for carrier/silence 1-255 sec 50
S8 Duration of delay for comma 0-255 sec 2
S9 Carrier detect response time .1-25.5 sec 6
S10 Delay carrier loss to hang up .1-25.5 sec 14
S11 Duration/spacing of DTMF tones .05-.255 sec 95
S12 Escape sequence guard time 0-5.1 sec 1
S18 Select test timer 0-255 sec 0
S25 DTR change detect time 0-.255 sec 5
S36 Negotiation fallback 0,1,3,4,5,7 7
S37 Maximum DCE line speed 0,3,5-12 0
S38 Delay before forced hang-up 0-255 sec 20
S46 Data compression control 136,138 138
S48 Feature negotiation action 0,7,128 7
S86 Connection failure cause code 0,1,4-14 --
S95 Negotiation message options 0-3,5 0
Download Driver Pack
After your driver has been downloaded, follow these simple steps to install it.
Expand the archive file (if the download file is in zip or rar format).
If the expanded file has an .exe extension, double click it and follow the installation instructions.
Otherwise, open Device Manager by right-clicking the Start menu and selecting Device Manager.
Find the device and model you want to update in the device list.
Double-click on it to open the Properties dialog box.
From the Properties dialog box, select the Driver tab.
Click the Update Driver button, then follow the instructions.
Very important: You must reboot your system to ensure that any driver updates have taken effect.
For more help, visit our Driver Support section for step-by-step videos on how to install drivers for every file type.