AT commands
Digi TransPort User Guide
119
S registers
S (Special) registers are registers in the router that are used to store certain types of
configuration information. They are essentially a legacy feature included to provide compatibility
with software that was originally designed to interact with modems. A full list of the registers is
provided under the
S registers
section.
D command: Dial a call
The ATD command causes the router to initiate an ISDN call. The format of the command
depends on the mode of operation.
When using the router to make data calls on one of the ISDN B-channels, enter the ATD
command followed by the telephone number. For example, to dial
01234 567890
enter the
command:
atd01234567890
Spaces in the number are ignored. If the call is successful the router will issue the
CONNECT
result code and switch to on-line mode.
Dialing with a specified sub-address
The ATD command may also be used to route a call to an ISDN sub-address by following the
telephone with the letter S and the required sub-address. The sub-address may be up to 15 digits
long. For example:
atd01234567890s003
Dialing stored numbers
To dial numbers that have previously been stored within the router using the
AT&Z
command,
insert the
S=
modifier within the dial string. For example, to dial stored number
3
, use the
command:
atds=3
Combining ISDN and X.25 calls
A further option for the ATD command for X.25 applications is to combine the ISDN call and the
subsequent X.25 CALL in the same command. To do this, follow the telephone number with the
=
symbol and the X.25 call string. For example:
atd01234 567890=123456789
Pressing any key while the
ATD
command is being executed will abort the call attempt.
H command: Hang-up
The
ATH
command is used to terminate an ISDN call. If the router is still on-line you must first
switch back to command mode by entering the escape sequence, such as
+++
, wait 1 second and
then enter an AT command or just
AT<CR>
.
After entering the
ATH
command, the call will be disconnected and the
NO CARRIER
result will be
issued.
