1209 Hz
1336 Hz
1477 Hz
1633 Hz
697 Hz
770 Hz
852 Hz
941 Hz
Tip: Click and hold any button to play the tone. Release to stop.
What is DTMF?
Dual Tone Multi Frequency (DTMF) is the signal system used by touch-tone telephones. Each key press generates two simultaneous tones - one from a low frequency group and one from a high frequency group.
The combination of these two frequencies uniquely identifies which key was pressed, allowing the telephone system to recognize the input.
Frequency Groups
Low Frequencies (Rows):
697, 770, 852, 941 Hz
High Frequencies (Columns):
1209, 1336, 1477, 1633 Hz
Note: A, B, C, D keys are rarely used but part of the DTMF standard
Use Cases
- • Telecommunications: Phone dialing systems
- • IVR Systems: Interactive voice response
- • Testing: Phone system diagnostics
- • Education: Learning about signal processing
- • Ham Radio: DTMF control systems
Technical Details
- • Each tone is 50ms minimum duration
- • Tones are sine waves (pure frequencies)
- • Used in landline and mobile networks
- • Replaced rotary dial pulse dialing
- • Also known as "Touch-Tone"