User`s guide

XSR User’s Guide 137
Chapter 8 Asynchronous and Synchronous Support
Configuring Dialer Services
AT Commands on Asynchronous Ports
On asynchronous ports, AT commands are used to establish and clear the call.
Refer to your modem documentation for a list of supported commands and
options. The modem should be configured to drive Data Carrier Detect and
Clear To Send CCITT V.24 signals and accept input of the Data Terminal
Ready signal set by the XSR.
V.25bis over Synchronous Interfaces
Dial services also support connections from the synchronous serial interface
to any modem that supports V.25bis. V.25bis supports two modes of
establishing or receiving calls: direct call and addressed call. Dial services
support connections using the addressed call mode and synchronous, bit-
oriented operation. The addressed call mode allows control signals and
commands to be sent over the modem interface to set up and terminate calls.
Devices used for dialing out must support certain hardware signals in
addition to V.25bis. When the XSR drops DTR, the device must disconnect
any calls that are currently connected. When the device connects to the
remote end, Data Carrier Detect (DCD) must be automatically asserted. For
many V.25bis devices, raised DCD requires a special cable to crossover DCD
and Data Set Ready (DSR) signals.
Table 8 lists V.25bis options. By default, the synchronous port will use V25bis.
The functions of these options are nation-specific, and they may have
different implementations. Refer to your modem documentation for a list of
supported commands and options.
Table 8 ITU-T V.25bis Options
Option Description
: Wait tone
< Pause
= Separator 3 - national use
> Separator 4 - national use
P Dialing to be continued in pulse mode - optional parameter