Why are some keys missing?

The usual causes are a quiet recording, lossy compression (low-bitrate AMR or MP3) damaging the tones, or a large level difference between the two tones. In Detection settings, lower the minimum level or relax the twist tolerance or strictness; for very short tones (under 40 ms) lower the minimum tone length. When speech or music overlaps the tones, raising the strictness reduces false detections.

What are the A, B, C and D keys?

Standard DTMF has 16 combinations in a 4×4 grid, and the fourth column (1633 Hz) is A–D. Ordinary phones don’t have them, but military phones, amateur radio, repeater control and some switches use them for control commands. This tool generates and detects all 16.

What kind of Morse recording works best?

A single steady tone (CW) at roughly 5 to 40 WPM. The strongest tone is found automatically; if something else in the recording is louder, set the frequency manually and narrow the bandwidth. Speed changes and Farnsworth spacing are handled automatically, and you’ll see a message when the signal is too noisy to decode.

Can I use it to find out someone’s phone number?

Please only analyse recordings you have the right to process, such as your own calls, test equipment or teaching material. The tool is meant for testing IVRs, radios and decoders and for learning signal processing. All analysis happens in your browser and files are never uploaded.

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☎️DTMF Tone Generator & Decoder, Plus Morse Code Audio Decoder

Phone keypad tones are DTMF (dual-tone multi-frequency): each key mixes one row tone (697, 770, 852 or 941 Hz) with one column tone (1209, 1336, 1477 or 1633 Hz). This tool has three parts. The generator gives you a 4×4 keypad, including the A–D keys found on professional equipment; hold a key to hear it, or type a dial sequence and set tone length, gap, comma pause, sample rate and twist (the level difference between the two tones), then play it or export a WAV to test IVR menus, radios and decoders. The decoder reads a recording or listens to your microphone live. It runs a Goertzel analysis on 30 ms windowed frames, checks that the row and column peaks stand out, that twist is within tolerance and that the tones carry enough of the energy, then debounces the result into a key sequence with start time, end time, length and level for each key; copy it, export CSV or look at the timeline. The Morse decoder finds the tone frequency automatically, extracts the envelope by quadrature demodulation, applies an adaptive threshold, then clusters dots, dashes and letter and word gaps. It adapts to speed changes, handles Farnsworth spacing, and gives the decoded text and WPM. Everything runs in your browser; recordings are never uploaded.

Free · No sign-up · Runs in your browserLast updated: 2026-10-26

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How to use DTMF Tones

1Generate: press keys or type a sequence, adjust tone length and gaps, then play or download a WAV
2Decode: choose a recording or start the microphone, and adjust level and twist tolerance if needed
3Read the detected keys (or Morse text), timestamps and timeline, then copy or export CSV

FAQ

Why are some keys missing?: The usual causes are a quiet recording, lossy compression (low-bitrate AMR or MP3) damaging the tones, or a large level difference between the two tones. In Detection settings, lower the minimum level or relax the twist tolerance or strictness; for very short tones (under 40 ms) lower the minimum tone length. When speech or music overlaps the tones, raising the strictness reduces false detections.
What are the A, B, C and D keys?: Standard DTMF has 16 combinations in a 4×4 grid, and the fourth column (1633 Hz) is A–D. Ordinary phones don’t have them, but military phones, amateur radio, repeater control and some switches use them for control commands. This tool generates and detects all 16.
What kind of Morse recording works best?: A single steady tone (CW) at roughly 5 to 40 WPM. The strongest tone is found automatically; if something else in the recording is louder, set the frequency manually and narrow the bandwidth. Speed changes and Farnsworth spacing are handled automatically, and you’ll see a message when the signal is too noisy to decode.
Can I use it to find out someone’s phone number?: Please only analyse recordings you have the right to process, such as your own calls, test equipment or teaching material. The tool is meant for testing IVRs, radios and decoders and for learning signal processing. All analysis happens in your browser and files are never uploaded.