Intel 536EX manual Intel Confidential, Fax Class 1 AT Commands, Fax Mode Command Descriptions

Fax Class 1 AT Commands

The ATDT <telephone number> command string causes the modem to originate a fax call. After dialing the telephone number, the modem sends out a calling tone (1100 Hz), recognizes the remote fax modem answer tone, and looks for the remote fax HDLC flags at 300 bps. If the HDLC flags are detected, the modem sends the DTE a ‘CONNECT’ message followed by the Class 1 HDLC frame information. If the HDLC flags are not detected within the time limit defined by S-register S7, the modem sends a ‘NO CARRIER’ message to the DTE and then hangs up the line. If the modem hangs up the line while processing the ATD command (that is, while the modem is on- hook), the modem responds back with an ‘ERROR’ message whenever the DTE issues one of the data stream AT commands.

The ATA command causes the modem to answer a fax call. After going off-hook, the modem sends the answer tone followed by HDLC flags. The modem then sends a ‘CONNECT’ message to the DTE and waits to receive the HDLC frame information from the DTE. In general, the ATA command performs three functions:

1.It places the modem off-hook.

2.It causes the modem to transmit the answer tone.

3.It causes the modem to act as if it received an AT+FTH=3 command from the DTE.

The following data mode and voice mode AT commands are supported in fax mode:

Data: All

Voice: +FCLASS, +VDR, +VNH, +VIP, and + VCID

Table 24. Fax Mode Command Descriptions

Command	Default		Description
		Fax Mode Selection: This command is used to select a fax class, indicate current fax
		class mode setting, and indicate supported fax classes. All fax mode commands,
		except for +FCLASS, are valid only in fax mode.
		+FCLASS?	Indicates current fax class selection
		+FCLASS = ? Indicates supported fax classes
+FCLASS	0	+FCLASS = n	Configures DCE for selected fax class. The modem
=1			responds back with an ‘OK’ message at the same
			DTE-to-modem data rate used to issue this command
		Range: 0, 1, 8
		n = 0*	Configures DCE for data modem operation
		n = 1	Configures DCE for fax Class 1 modem operation
		n = 8	Configures DCE for IS-101 voice mode

NOTE: An asterisk (*) denotes the factory-default setting.

536EX Chipset Developer’s Manual 67

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