1. Acronym for Dual Tone Multi-Frequency, the system used by touch-tone telephones. DTMF assigns a specific sound frequency, or tone, to each key so that it can easily be identified by a monitoring microprocessor. That frequency is then translated into a usable analog or digital signal. This is commonly known as Touch Tone.
2. Audible tones which conform to North American Telephone Standards. These are generated by push-button telephones to dial telephone numbers, as well as to provide control or data input to voice processing systems. Especially significant in the operation of most automated attendants and Fax/data line sharing devices.