DTMF Tone Software Development

Dual-Tone Multi-Frequency (DTMF) is the signaling system behind touch-tone telephone dialing. Every key on a phone keypad produces a unique pair of simultaneous tones — one from a low-frequency group (697, 770, 852, 941 Hz) and one from a high-frequency group (1209, 1336, 1477, 1633 Hz). The combination of these two tones identifies each key (0–9, *, #, A, B, C, D) and can be reliably detected by a DTMF decoder.

DTMF was introduced by AT&T in 1968 and quickly became the global standard for in-band dialing, replacing single-frequency pulse dialing. It is used not only for telephone dialing but also in voicemail systems, IVR menus, telephony APIs, and even some radio and amateur communication systems.

This project provides a JavaScript DTMF encoder and decoder that runs entirely in the browser. The encoder generates authentic DTMF tones using the Web Audio API, while the decoder analyzes incoming audio to detect the number dialed. No server-side processing — everything runs client-side.

Important Disclaimer. This content is provided for educational or entertainment purposes only. The software active on this page comes with NO WARRANTIES. Not even the implied warrantee of merchantability or fitness for any purpose whatsoever. The author retains copyright and publication rights under the Apache License. All other rights, risks, and responsibilities belong to the user.

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