Chapter 3 – Fax Class 2 Commands
Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306C)
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Service Class 2 Parameters
All Service Class 2 parameters can be read, written, and tested for range of legal values by the DCE. The
general syntax is described in the Voice Commands Overview section.
Group 3 FAX devices negotiate session parameters in DIS, DCS, and DTC frames. The following
parameters are provided to condition the facsimile DCE for the capabilities it will offer and to report the
session settings negotiated.
The three primary T.30 session parameters are +FDCC, +FDIS and +FDCS. They are compound
parameters.
Figure 3-2. T.30 Session Parameter Relationships
Command: +FDCC DCE Capabilities Parameters
Description:
+FDCC
allows the DTE to sense and constrain the capabilities of the facsimile
DCE from the choices defined in CCITT T.30 Table 2. When +FDCC is
modified by the DTE, the DCE FDCC into +FDIS.
Write syntax:
+FDCC=VR,BR,WD,LN,DF,ED,BF,ST
Valid values:
See Table 3-2.
Default values:
0,3,0,2,0,0,0,0 (9600 bps fax models) or 0,5,0,2,0,0,0,0 (14400 bps fax
models)
Command: +FDIS Current Sessions Capabilities Parameters
Description:
The +FDIS parameter allows the DTE to sense and constrain the capabilities
used for the current session. The DCE uses +FDIS to generate DIS or DTC
messages directly, and uses +FDIS and received DIS messages to generate
DCS messages.
The DCE initializes the +FDIS parameter from the +FDCC parameter on
initialization, when +FDCC is written, and at the end of a session.
Write syntax:
+FDIS=VR,BR,WD,LN,DF,EC,BF,ST
Valid values:
See Table 3-2.
Default values:
0,3,0,2,0,0,0,0 (9600 bps fax models) or 0,5,0,2,0,0,0,0 (14400 bps fax
models)
