dr_pc
13-04-2004, 07:53
When you dial a number from your telephone, you can hear a different sound for each button you press. These tones are called DTMF (Dual Tone Multiple Frequency) codes as each sound consists of two tones modulated together.
Here's a list of the frequencies used. The official minimum on/off times are 100msec pulse widths, but most equipment will work with other timings
http://www.ukhp.info/phreak/uktones.htm
Tones are also used for letting the user know if the number they are calling is engaged etc. Here's the list. All on/off times are in msec.
http://www.ukhp.info/phreak/uktones.htm
salam
Here's a list of the frequencies used. The official minimum on/off times are 100msec pulse widths, but most equipment will work with other timings
http://www.ukhp.info/phreak/uktones.htm
Tones are also used for letting the user know if the number they are calling is engaged etc. Here's the list. All on/off times are in msec.
http://www.ukhp.info/phreak/uktones.htm
salam