Technics MT5634SMI-34 manual Voice Commands, SocketModem Global MT5634SMI Developer’s Guide, Digit

			Chapter 6 – Voice Commands
Command:	+FCLASS=8 DTMF Detect		Detect and Control DTMF
Values:	8 characters, case sensitive
Description:	The +FCLASS=8 command is used to detect and control DTMF using the procedure below:
	1.	Enter the command AT+FCLASS=8 <cr> to the modem.
	2.	Call into modem with phone. A ￿r (incoming ring indication) is displayed, followed by OK. The

modem is now in Online Voice Command mode, allowing DTMF characters to be passed through from the remote phone. The characters are displayed as shown below: AT+FCLASS=8

OK

￿R is Ring

￿/￿1￿1￿~

The Data link escape character (￿), and the ‘start of DTMF tone shielding’ character (¤) are both output once a button is pressed. The DTMF digit will continue to be output along with a ￿ until the button is released. Then another ￿ is output along with a ‘DTMF transitions to off’ (~) character.

Silence on the line is indicated with a (￿s) displayed.

DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone’s touch keys. DTMF has generally replaced loop disconnect (“pulse” or “rotary”) dialing. With DTMF, each key you press on your phone generates two tones of specific frequencies. So that a voice can’t imitate the tones, one tone is generated from a high-frequency group of tones and the other from a low frequency group.

Touch Tone Signals
Digit	Low frequency	High frequency
1	697 Hz	1209 Hz
2	697	1336
3	697	1477
4	770	1209
5	770	1336
6	770	1477
7	852	1209
8	852	1336
9	852	1477
0	941	1336
*	941	1209
#	941	1477

When any key is pressed, both the high and low tones of the row are generated, hence the name “dual tone”. For example, pressing the ‘5’ button generates the tones 770Hz and 1336Hz. The frequencies were chosen to avoid harmonics (no frequency is a multiple of another, the difference between any two frequencies does not equal any of the frequencies, and the sum of any two frequencies does not equal any of the frequencies).

For additional information on DTMF, see the Telecommunications Industry Association’s web site at http://www.tiaonline.org/resources/other_links.cfm.

Command:	AT+FCLASS=? <Enter>	Display Service Class Capabilities
Values:	0, 1 (other values are reserved)
Default:	0
Result Codes:	OK if the command is accepted; ERROR if the parameter value is out of range.
Description:	The +FCLASS=? command displays the set of Service Classes supported by the modem from the
	list of values (e.g., 0,1 for a modem that supports data comm plus fax Service Class 1). This

command returns the service class or classes available with the modem. The modem returns a list of all supported values, separated by commas if more than one class is supported. For example, a modem that supports data communications, Class 1 fax, Class 2 fax, and Voice mode functions would respond with "0,1, 2.0, 8".

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