Reference Guide for the Model XM128 ISDN Digital Modem
C-2 AT Command Set Reference
AT Command Descriptions
The AT command is a command in asynchronous data format issued by the computer to the Model
XM128 modem through the asynchronous computer-modem interface. AT commands control the
behavior and actions of the modem.
To send an AT command from a computer to the Model XM128 modem, the following rules apply:
• You must be running a communication software.
• The modem must be in the command state.
The commands A/, A>, and +++ are exceptions. These commands are not preceded by AT or
followed by any more characters.
• The AT command prefix can be typed in either uppercase letters (AT) or lowercase letters (at).
Do not combine uppercase and lowercase letters in the prefix.
Table C-1
, Table C-2, Table C-3, and Table C-4 list the AT commands supported by the Model
XM128 modem. An asterisk (*) following a command option or value indicates that it is a default
setting when the Model XM128 modem is shipped. Table C-1 lists the basic AT command set.
Table C-1. Basic AT command set
Command Options Function and description
A/ Re-executes the last command once.
A> Reexecutes the last command once or repeats the last call up to 9 times. You
can abort this command by pressing down on any key on the keyboard or front
panel. This command is also aborted when a successful connection with a
remote modem is made. See also S-register S8. For a description of Basic
S-registers, refer to Table D-3 on page D-4 in Appendix D, “Status Registers
and Result Codes."
Pressing any
key
Terminates the current connection attempt when any key is pressed.
+++ Exits the data transfer state and begins the command entry state.
A Goes online in answer mode. See also S-registers 39.2 and S43.6. For a
description of Extended S-registers, refer to Table D-4 on page D-5 in
Appendix D, “Status Registers and Result Codes."
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