A fancy term to describe push button or touchtone dialing. Each DTMF has two tones, one low frequency and one high frequency, which combine to make the tone. This is done so that the human voice cannot reproduce the sounds. Story: Captain Crunch. In the 1960s, a gentleman got a whistle from a Captain Crunch Cereal box and was able to reproduce the sounds made from the Single Tone telephone. He was able to make free long distance phone calls. The telecom industry came out with DTMF to prevent that from happening again.