What Is DTMF?
Dual-Tone Multi-Frequency tones, or DTMF, is a nearly 60-year telecommunications mainstay recognized worldwide. Often referred to by its 1963 Bell System commercial name ‘touch tone’, you interact with DTMF every time you ‘press 1 for Sales’ on a telephone keypad.
DTMF tones are produced when someone presses the numbers of a telephone keypad. Each number key has two tones, one high and one low frequency.
The columns on the keypad are assigned to the high-frequency signals, while the rows are assigned to the low-frequency signals. These in-band signals are combined to create a unique signal pair and then transmitted through voice channels.
DTMF is present across a multitude of services and facilities, from telephone banking and bill payment services to Interactive Voice Response (IVR) menus and conferencing services like Zoom.
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