DTMF (touch tones)
DTMF is the system of dual tones a phone sends when you press a key, used to pass digits through a call.
Each key sends two simultaneous tones, which is what makes them distinguishable from speech and from each other. It is why phone menus can reliably read a keypress even on a noisy line.
It stays relevant for voice agents in two ways: callers still expect to be able to press a key, and some systems on the other end of a transfer require digits rather than speech. Agents also use it in reverse — navigating another company’s phone menu on your behalf means sending the right tones at the right moment.
Related
- IVR (interactive voice response) — An IVR is an automated phone menu that routes callers based on keypresses or short spoken commands.
- Warm transfer — A warm transfer is handing a call to a person while passing on the context, rather than dropping the caller into a fresh conversation.