Keyboard: 0-9, A-D, * #, backspace
DTMF, or Dual-Tone Multi-Frequency, is the signal generated by a telephone keypad. Each key combines two specific frequencies (one low, one high) to produce a unique tone. This dialer uses the Web Audio API to generate pure sine waves for authentic sound.
The standard defines four low frequencies (697, 770, 852, 941 Hz) and four high frequencies (1209, 1336, 1477, 1633 Hz). Each key is a sum of one low and one high frequency.
Yes, you can generate sequences and adjust tone duration to test automated phone menus.