dual-tone multifrequency
  • A telephone signaling system which utilizes tones which are a mixture of two frequencies. Each mixture identifies any of the 12 dial keys, 0-9, *, and #, as found on most touch-tone phones. The tone heard when a number 5 is pressed on such a phone, for instance, is a combination of two such frequencies, specifically 770 Hz and 1336 Hz.
  • A communications method utilizing dual-tone multifrequency (1).
  • acronym DTMF

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