Multi-Tech Systems Fax Mode Selection, Fax Origination, Fax Answering, Fax Control Transmission

Chapter 6 – Fax Class 1 and Class 1.0 Commands
Multi-Tech Systems, Inc. SocketModem MT5600SMI Developer’s Guide 87
Fax Mode Selection
Fax Class 1 and Fax Class 1.0 commands are identified in Table 6-1. F ax Class 1.0 includes all Fax
Class 1 commands
Table 6-1. Fax Class 1 and Fax Class 1.0 Commands
Command/Parameter Function Applicable in
Fax Class 1
Applicable in
Fax Class 1.0
+FCLASS=<class> Select, read or test service class X X
+FAA=<value> Auto answer enable - X
+FAE=<value> Auto answer enable X X
+FTS=<time> Stop transmission and pause X X
+FRS=<time> Wait for silence X X
+FTM=<mod> Transmit data with <mod> carrier X X
+FRM=<mod> Receive data with <mod> carrier X X
+FTH=<mod> Transmit HDLC data with <mod> carrier X X
+FRH=<mod> Receive HDLC data with <mod> carrier X X
+FAR=<off/on> Adaptive reception control - X
+FCL=<time> Carrier loss timeout - X
+FDD=<value> Double escape character replacement control - X
+FIT=<time>, <action> DTE inactivity timeout - X
+FPR=<rate> Fixed DTE Rate - X
+FMI? Report manufacturer ID - X
+FMM? Report model ID - X
+FMR? Report revision ID - X
+FLO Flow Control - X
&K Local DTE-modem flow control (see Call
Control Section)
XX
AAnswer XX
D<string> Dial X X
H Hangup (see Call Control Section) X X
X stands for Applicable. - stands for Not Applicable.
Fax Origination
Origination of fax calls is made using the ATD command. Upon com pletion of the dial function, a calling
tone at 1100 Hz is transmitted, with a cadence of 0.5 seconds on and 3 seco nds off. The modem
automatically enters mode +FRH=3 and sends the CONNECT message to the DT E when FSK flags are
detected from the remote.
Fax Answering
Answering of fax calls is identical to answering of data calls with the exception that the modem enters the
fax handshaking mode instead of the data handshaking mode after going of f-hook. If +FAE=0, the
modem, after sending answer tone, automatically enters fax mode ( +FTH=3), sends the CONNECT
message to the DTE, and starts sending FSK flags. If +FAE=1, the modem determines whether the caller
is a data modem or fax modem and sends the DATA or FAX result code, res pectively, to the DTE.
Fax Control Transmission
Fax control transmission is initiated by the +FTH=<mod> com mand. After this command is issued, the
modem generates the CONNECT message and transmits carrier in the m odulation scheme specified by
the parameter n. The modem then transmits HDLC flags for a minimum of 1 sec ond. The modem
continues to transmit the HDLC flags until it receives a character from the DTE.
When characters are received from the DTE, the modem adds start and end fla gs, performs zero-bit
insertion, generates FCS, and deletes <DLE><chr> character pair s before transmitting the characters to
the remote fax machine. Each <DLE><DLE> sequence is transm itted as a single <DLE>. <DLE><ETX>
is considered as the end of frame marker and is not transmitted. All data r eceived from the DTE after