User guide

Appendices 67
Appendix D: Internal Modem
Some models of the ACS 6000 advanced console server come equipped with an internal modem.
This modem is used to originate and answer phone calls and establish communication with other
modems to transmit data.
Controlling the modem’s functions is done by using the “AT” commands. These commands are
used to instruct the modem to perform functions such as dialing or answering calls and are
normally automatically issued by communication software. However, for some applications,
custom software may have to be written due to the absence of a normal operating system.
The modem will automatically accept and process AT commands at most standard DTE (Data
Terminal Equipment) speeds and parity settings. For each command issued, the modem will
respond with a result code to inform you of the modem’s status. The format of a basic AT
command and result code is as follows:
AT<Command><CR>
OK
AT = Attention.
<Command> = any valid command
<CR> = Carriage Return or Enter key
OK = Result Code
Table D.1: Sample Command String
Command Description
ATDT7678900<CR> Instructs the modem to dial the number 7678900 and attempt to
connect to the remote device.
ATS0=2<CR> Enables auto answer option. When the modem detects a ring, it will
attempt to answer after two rings.
Table D.2: Basic AT Commands
Command Description
ATA/ Repeat the previous command.
ATA Answer.
ATB0 CCITT operation at 300 or 1200 bps.
ATB1 Bell operation at 300 or 1200 bps (default).
ATD Dial.
ATD0-9 Dial the DTMF digits 0 to 9.