Playback Mode
Phone Keypad
Current Tone Frequencies
Press a key to see its frequencies
Tone Settings
100ms
50ms
70%
📚 DTMF Frequency Reference
| Key | Row (Hz) | Column (Hz) | Letters |
|---|---|---|---|
| 1 | 697 | 1209 | - |
| 2 | 697 | 1336 | ABC |
| 3 | 697 | 1477 | DEF |
| 4 | 770 | 1209 | GHI |
| 5 | 770 | 1336 | JKL |
| 6 | 770 | 1477 | MNO |
| 7 | 852 | 1209 | PQRS |
| 8 | 852 | 1336 | TUV |
| 9 | 852 | 1477 | WXYZ |
| * | 941 | 1209 | - |
| 0 | 941 | 1336 | + |
| # | 941 | 1477 | - |
How DTMF Works
DTMF (Dual-Tone Multi-Frequency) generates two simultaneous sine wave tones when you press a key. Each button produces a unique combination of row and column frequencies. This system allows telephone networks to decode which button was pressed by analyzing the two frequencies.
Need to convert or trim reference recordings after testing? Our partner AudioKit offers a privacy-first audio editor that pairs perfectly with DTMF signal workflows.