3 service class 2 action commands – Comtrol AT Command Set Rev A User Manual

Page 178

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AT Commands Reference Manual

Conexant

100722B

5-6

5.2.3

+FREV? - Identify Product Revision

The +FREV? command causes the DCE to send a message identifying the DCE product
model revision number. The message format is the same as the ATI3 message, e.g.:

VX.X-F_A
OK

5.3

Service Class 2 Action Commands

These commands transfer data, and punctuate sessions. They also release specific T.30
messages. All action commands must be the last command on a command line as
indicated by the terminating <CR>.

All action commands initiate processes. The modem will not accept other commands
from the DTE until the modem issues a final result code (e.g., OK, CONNECT). The
modem will abort the process if it receives any character before the final result code is
issued.

5.3.1

ATD - Originate a Call

Syntax: ATD....<CR>

The DCE can support a DTE command to originate a call using the ATD command (see
Section 3.2).

If this command is unsuccessful, the DCE reports an appropriate failure or error type
result code such as NO CARRIER, NO DIAL TONE, or BUSY (see Section 3.3).

If this call is successful, the typical DCE response is:

ATDnn..nn

(go off-hook, dial, get CED)

+FCON

(DCE detects flags)

[+FCSI:<remote ID string>]
+FDCS:<T.30 subparameter string>
OK

The DCE dials, detects call progress, and generates the CNG tone. It then waits for a DIS
frame. On detection of the first Phase B preamble (V.21 ch. 2 modulated by 300 bps
HDLC flags), it reports the “+FCON” message to the DTE. The DCE then switches to
19200 bps.

The DCE generates a DCS frame based on the received DIS frame and on the previously
set +FDIS parameter. A +FDT command from the DTE releases the DCE to transmit that
DCS frame.

The DCE reports the initial received T.30 negotiation messages, including the DIS frame
and the optional CSI ID string. The +FDIS: report is followed by the OK final result
code.

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