FAX Commands and Responses


All FAX messages have the prefix +F. The three types of messages are action commands, responses, and parameters. Commands go from the DTE to the DCE. Responses are messages from the DCE to the DTE. Parameter values may pass in either direction. The DTE sets values; the DCE reports values.

Parameters are assigned values by commands of the form +FPARM=value, where PARM means any parameter name. Current parameter values can be read by the DTE using commands of the form +FPARM?. The DCE responds with a string of values or lines of info-text.

The +F parameters may be changed while the modem is in data mode and off line. In addition, the Class 2 FAX commands +FMI?, +FMM?, and +FMR? are valid while the modem is in data mode. These three commands invoke information text that provide manufacturer identification, model identification, and revision identification respectively.

Invalid FAX commands and FAX commands that cannot be executed will produce an ERROR result code.

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