Multi-Tech Systems MTA128ST-USB - Manual (Page 58)

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MultiModemISDN User Guide
MTA128ST-USB
Using AT Commands to Operate the MTA128ST-USB
You can configure and operate the MTA128ST-USB entirely with AT commands if you
like. But remember, you can issue AT commands only from a terminal or from a computer
running a communications program in terminal mode. This section describes how to use
AT commands for basic operations, such as calling, answering a call, and hanging up.
Modes of Operation
The MTA128ST-USB has three modes of operation. They are:
•
Offline Command Mode—The MTA128ST-USB communicates with the terminal or
computer and responds to AT commands. There is no data communications link with
a remote device.
• Data Mode—The MTA128ST-USB enters data mode when it makes a successful
data communications link with a remote device. In data mode, the TA can send and
receive data, but it does not respond to AT commands. Instead it treats them as data
and transmits them to the remote device.
• Online Command Mode—The MTA128ST-USB responds to AT commands while
maintaining a data communications link; however, transmission of data is suspended.
To enter online command mode from data mode, type the escape sequence
+++AT<cr>. To return to data mode from online command mode, type ATO<cr>.
Making a Call
Before you can place a data call, configure the MTA128ST-USB for the local switch type,
serial port speed, and the data type of the ISDN device you want to call. See Chapter 3,
Configuration Utilities.
Dialing
To dial a number using AT commands, you must first start a data communications
program. In the program’s terminal mode, type ATDxxxxxxx<cr>, where xxxxxxx is the
telephone number you want to dial, and <CR> is the carriage return character that is sent
when you press the ENTER key, e.g., ATD7853500<cr>. The dial string can contain up
to 80 characters.
To place an ML-PPP call, use an ampersand character (&) to join two telephone
numbers, e.g., ATD7853500&7853502<cr>. The telephone numbers can be the same or
different. Using this method, two B-channels are activated to transmit data at an
aggregate speed of 128 Kbps.
To make it easier to read the dial string, you can use hyphens, spaces or parentheses.
These characters are ignored by the MTA128ST-USB. For example, the MTA128ST-USB
would read the following dial strings the same way:
ATD16127853500 <cr>
ATD 1-612-785-3500 <cr>
ATD 1 (612) 785-3500 <cr>