Perle 833IS User Guide 241
Appendix 2: AT Command Set

About AT Command Set

In this chapter you will read about:
■AT Commands
■Error Detection and Data Compression Commands
■S - Registers
■S - Register Definitions
■AT Command Set Summary
The modem will respond to the commands detailed below. Parameters applicable to
each command are listed with the command description.
A single command string can be up to 40 characters in length, including the “AT”.
The modem behaves differently from a stand-alone modem because it does not
directly interface to the telephone line. Phone call handling is by the Line Interface.
Once the call is established it is switched to the modem. Therefore, modem
commands that do line control (such as ATA, ATH) are not handled solely by the
modem. Although there are significant differences between making a call on an
ISDN line and a standard phone line, the 833IS will make all the necessary
conversions.

AT Co mma nds

A/ - Re-execute
Command The modem behaves as though the last command line had been re-sent by the DTE.
"A/" will repeat all the commands in the command buffer.
The principal application of this command is to place another call (using the Dial
command) that failed to connect due to a busy line, no answer, or a wrong number.
This command must appear alone on a command line. This command should not be
terminated by a carriage return.