Call Control; Managing A Csd (Data) Call - Motorola g20 Developer's Manual

AT Commands Reference
Example
AT+MPDPM
+MPDPM: 0
OK
4.3

CALL CONTROL

4.3.1

Managing a CSD (Data) Call

The g20 working modes can be divided into two modes of operation.
• Data Mode: In this mode, once the g20 has established a link with the remote modem, it does not respond to any data passing
through it (except for the Escape Sequence search). The g20 becomes a transparent link, connecting the terminal with the
remote side.
• Command Mode: In this mode, the g20 responds to the AT commands issued by the terminal. This is the default working
mode.
It is possible to switch between the operating modes.
The operating modes can operate simultaneously using the Mux.
Note
The Terminal mode allows you to instruct the modem to dial a remote modem by issuing the Dial command followed by the
phone number. You can also include dial string modifiers in your command line to give the modem additional instructions. The
following dial modifiers are available on most modems:
• ","- Pause
• ";" - Return to the Command mode after dialing - used for a voice call.
4.3.1.1 Simple Dialing
In order to instruct the modem to dial a remote modem from an ordinary tone-dialing telephone line, enter the Dial command
followed by the phone number. For example, type the following command:
ATD 876-5555 <Enter>
If you receive characters which were sent, you can disable this with using the Echo command (ATE0 <Enter>).
Note
After issuing the Dial command, and if the remote modem answers the call, the two modems send high-pitched carrier tones to
one another which establish the transmission speed and other parameters for the data connection. This process is called
negotiation, or handshake.
After the negotiation process, the message, "CONNECT" followed by the connection speed, is received.
If the other phone line is busy, the message "NO CARRIER" is received.
If the other modem does not answer, the message "NO CARRIER" is received.
Once a connection has been established, the modem is ready to immediately begin transmitting and receiving data. This may
vary from sending messages to each other, sending or receiving files, logging on to an information service, or any other data
communication task you wish to perform.
50 98-08901C68-O