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9–1
Chapter 9
AT COMMAND SET SUMMARY
An AT command is a command issued by the computer/terminal to the modem
through the asynchronous computer-modem interface in asynchronous data for-
mat. AT commands control the modem's behavior and actions. To send an AT
command from a computer to the modem, you must be running a communication
software and the modem must be in command state.
An AT command prefix (ATtention) precedes each command line, except in the
case of A/, A>, and +++. A/ re-executes the last command once. A> re-executes
the last command once, and repeats the last call up to 9 times until aborted by
physically pressing any key on the keyboard or front panel or until a successful con-
nection with a remote modem has been made. These commands are not preceded
by AT or followed by more characters. Up to 40 commands can be entered in a
command line with a single AT prefix. Be sure to either use all capital letters (AT)
or none at all (at).
+++ is the escape sequence code that is entered in data state to return the modem
to command state. The modem will accept AT commands only while it is in com-
mand state.
Basic AT Command Set
A list of the basic AT command set follows. Each command should be entered after
an AT prefix. A plus sign (+) placed before a command in the list indicates that it is
a default setting.
A Goes on-line in answer mode. (See also S39b2, S43b6)
+ B0 Selects ITU-T V.22 for 1200 bps communication. (Default)
B1 Selects Bell 212A for 1200 bps communication.
D Enters originate mode, dials the number that follows; attempts to go
on-line. (See also S35b4, S38b0)
Digits and modifiers that can be used with the D command:
0-9,#,* Digits for dialing.
P Pulse dial.
T Tone dial.
W Wait for a second dial tone. (See also S6)