Specifications

Chapter 3 – Fax Class 2 Commands

Multi-Tech Systems, Inc. SocketModem MT5600SMI/MT5656SMI Reference Guide (S000306B) 77

Command and Syntax Guidelines

Mode Entry Commands

+FCLASS=2 - Select Facsimile Class 2 Mode

+FCLASS=2 selects the Fax Class 2 Mode (see Generic Modem Control).

DTE Commands

The ISO 646 character set (CCITT T.50 International Alphabet 5, American Standard Code for

Information Interchange) is used for the issuance of commands and responses. Only the low-order 7 bits

of each character are used for commands or parameters; the high order bit is ignored. Upper case

characters are equivalent to lower case characters. For Phase C data transmission or reception, all 8 bits

are needed.

DTE Command Lines

A command line is a string of characters sent from a DTE to the modem (DCE) while the modem is in

a command state. A command line has a prefix, a body, and a terminator. Each command line (with

the exception of the A/ command) must begin with the character sequence AT and must be

terminated by a carriage return. Commands entered in upper case or lower case are accepted, but

both the A and T must be of the same case, i.e., "AT" = ASCII 065, 084 or “at” = ASCII 097, 116. The

body is a string of commands restricted to printable ASCII characters (032 - 126). Space characters

(ASCII 032) and control characters other than CR (ASCII 013) and BS (ASCII 010) in the command

string are ignored. The default terminator is the ASCII <CR> character. Characters that precede the

AT prefix are ignored. The command line interpretation begins upon receipt of the carriage return

character.

Facsimile Command Syntax

After the "AT" or "at" prefix, facsimile commands use extended syntax. Each command is preceded

by the “+F” character and consists of single characters and a decimal parameter (if applicable)

terminated by the semicolon “:” character (ASCII 059) or by the <CR> that terminated the command

line. A missing decimal parameter is evaluated as 0.

For example, the command to instruct the modem to automatically answer a data or fax call and also

enable reception is:

AT+FAE=0; +FCR 1 <CR>

Basic data mode and fax service class mode select commands are:

AT+FCLASS=0 <CR> for Data Mode

AT+FCLASS=1 <CR> for Service Class 1 Fax

AT+FCLASS=1.0 <CR> for Service Class 1.0 Fax

AT+FCLASS=2 <CR> for Service Class 2 Fax

In Class 2, the DCE makes and terminates calls, manages the communication session and

negotiates (T.30 protocol) and transports the image date to DTE. The T.4 protocol management of

image data, etc., is done by DTE.

The response to

AT+FCLASS= 0<CR> in Data Mode

AT+FCLASS=2<CR> in Service Class 2 Fax