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DTMF Touch-Tone Frequencies
Complete telephone dual-tone multi-frequency (DTMF) keypad chart for digits, star, hash and A–D.
| Low tone ↓ / High tone → | 1209 Hz | 1336 Hz | 1477 Hz | 1633 Hz |
|---|---|---|---|---|
| 697 | 1 | 2 | 3 | A |
| 770 | 4 | 5 | 6 | B |
| 852 | 7 | 8 | 9 | C |
| 941 | * | 0 | # | D |
Each key emits one row frequency plus one column frequency at the same time. Example: 5 = 770 Hz + 1336 Hz. A–D keys appear on extended 4-column DTMF equipment.
Geocaching tip: In audio puzzle recordings, look for two simultaneous spectral peaks matching one row and one column.