2006-12-20 16:05:45 · 2 answers · asked by Slang 1 in Consumer Electronics ➔ Cell Phones & Plans
DTMF are the tones you hear when you press numbers on the keypad (Dual Tone Multiple Frequency)
In-band means that the tones are carried over the voice channel. Outband means they are carried on a separate signalling channel and not the voice circuit. In this case, they are no longer tones, instead they are messages that represent the tones. This signalling network uses the SS7 protocol.
With GSM phones, the DTMF is not generated by the phone. Instead, when you press a number during a call, the phone sends a message representing the pressed key to the exchange (MSC). (out of band signalling) It is the MSC that injects the tone onto the voice circuit (inband signalling)
2006-12-21 00:17:54 · answer #1 · answered by amania_r 7 · 3⤊ 0⤋
Out Of Band Dtmf
2016-10-31 07:30:10 · answer #2 · answered by ? 4 · 0⤊ 0⤋