Comtrol AT Command Set Rev A - Manual (Page 179)

AT Commands Reference Manual
100722B Conexant 5-7
5.3.2 ATA - Answer a Call
The DCE can support a DTE command to answer an incoming call using the ATA
command (see Section 3.2).
The DTE may issue an Answer command in response to an incoming ring.
If the Answer command is unsuccessful, the DCE will report an appropriate failure or
error type result code, such as NO CARRIER (see Section 3.3).
Manual Call Answer
If this call is successful, the typical DCE response (answer and receive) is:
+FCON
[+FTSI:]
+FDCS:
OK
(DTE should issue +FDR command here)
Upon receipt of an Answer command from the DTE, the DCE answers and generates the
CED tone. The DCE then generates a DIS frame (derived from the +FDIS parameter) and
hunts for the first T.30 negotiation frames. Upon 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 DTE should report the initial received T.30 negotiation messages, including the DCS
frame. The +FDCS: report will be followed by the OK final result code.
Automatic Answer
The modem provides for automatic answering of incoming calls. If configured for
automatic answer, the modem answers an incoming call in compliance with T.30, and
reports the same messages as described for manual answer.
Connection as a Data Modem
If configured to do so by the +FAA parameter, the DCE will adaptively answer as a
facsimile DCE or as a data DCE. If the DCE answers as a data DCE, it resets the
+FCLASS parameter to 0 and issues the appropriate final result code (e.g., CONNECT,
or NO CARRIER) to the DTE.
5.3.3 +FDT - Data Transmission
Syntax: +FDT
The +FDT command prefixes Phase C data transmission. When the DCE is ready to
accept Phase C data, it issues the negotiation responses and the CONNECT result code to
the DTE.
In Phase B, the +FDT command releases the DCE to proceed with negotiation, and
releases the DCS message to the remote station. In Phase C, the +FDT command resumes
transmission after the end of a prior transmit data stream.