DTMF Tone Generator

Play Dual-Tone Multi-Frequency (touch-tone) signals — the sounds your landline phone made when you dialed a number. Each key is the sum of one row and one column sine wave. Tap a key to hear it, or paste a sequence and dial it like a phone.

Sequence Dialer

Sequence (digits, * # A-D, comma or , for pause)

Whitespace, hyphens, and parentheses are stripped. Use , or p for a half-second pause; w for a full pause.

Tone duration (ms)

Gap between tones (ms)

Volume

Idle. Press a key or dial the sequence.

Keypad

Row frequencies: 697, 770, 852, 941 Hz

Column frequencies: 1209, 1336, 1477, 1633 Hz

DTMF Frequency Matrix

	1209 Hz	1336 Hz	1477 Hz	1633 Hz
697 Hz	1	2	3	A
770 Hz	4	5	6	B
852 Hz	7	8	9	C
941 Hz	*	0	#	D

DTMF (ITU-T Q.23 / Q.24) replaced rotary pulse dialing in the 1960s — AT&T trademarked it as Touch-Tone. The four extra A–D keys exist in the spec (1633 Hz column) but were dropped from consumer phones; they survive in amateur radio and some military autodialers. Each tone pair was chosen so no row frequency is a harmonic of any column frequency, which lets the receiver tell them apart even on a noisy line. The minimum recommended tone duration is 40 ms, with at least 40 ms of silence between tones.