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.
The sounds the network plays back to you (dial tone, busy signal, ringback) are a different set: hear them by country on the telephone tones page.
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"