This signaling system replaced mechanical pulse dialing by sending distinct audio frequencies down the telephone line to the central office switch. While early proprietary systems used single tones, the universal standard became dual-tone multi-frequency, which combines a high and a low frequency for each key press. This allowed for much faster dialing and enabled users to interact with automated voice systems.
The IVR won't recognize your input if the handset is set to pulse instead of tone dialing.
Also heard as
- DTMF
Do not mix it up with
- Touch-tone dialing: Tone dialing is the generic technical method; Touch-Tone was the Bell System's trademarked name for it.
Related terms
Touch-tone dialing
The Bell System's trademarked implementation of dual-tone multi-frequency telephone signaling.
Pulse dialing
A legacy telephone signaling method that rapidly connects and disconnects the line to indicate digits.
In-band signaling
The transmission of network control signals over the same channel used for the actual voice or data payload.