What frequencies are synthesized for each DTMF digit?

Per ITU-T Q.23, each key combines one low-group tone (697, 770, 852, or 941 Hz) and one high-group tone (1209, 1336, 1477, or 1633 Hz).

What is twist in DTMF signaling?

Twist measures the power difference in decibels between the high-frequency and low-frequency tone groups, within a standard acceptance window of −8 dB to +4 dB.

Why include a 5 ms raised-cosine ramp on tone edges?

The ramp rounds the leading and trailing edges of each tone burst to eliminate audible switching clicks without violating minimum detection duration.

When should I select 8 kHz instead of 44.1 kHz?

Select 8 kHz to simulate standard G.711 narrow-band telephony audio, and use 44.1 kHz for broadcast, podcasting, or general multimedia playback.

Are the military and routing tones A, B, C, and D supported?

Yes, letters A through D represent the fourth-column high-frequency tone (1633 Hz) paired across each of the four standard low-frequency tones.

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DTMF Tone Generator

Generate ITU-T Q.23/Q.24-compliant DTMF touch-tone sequences (0-9, *, #, A-D) as audio files — IVR prompts, PBX testing, film props, decoder development. Tone/pause timing, twist and level configurable, Q.24 compliance checked.

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What this tool helps you do

Dual-Tone Multi-Frequency signaling uses one low-group (697/770/852/941 Hz) and one high-group (1209/1336/1477/1633 Hz) sine per key, per ITU-T Q.23. This generator synthesizes any keypad sequence with exact per-digit timing and encodes it to WAV, MP3, FLAC, M4A or OGG. Defaults follow the Q.24 receiver recommendations: tone ≥ 40 ms (default 90 ms), pause ≥ 40 ms (default 60 ms), signalling velocity ≤ 10 digits/s, and twist — the high-group power relative to the low group — kept inside the −8…+4 dB acceptance window. Every tone edge gets a 5 ms raised-cosine ramp so clips never click while the mark duration stays compliant. A compliance flag reports whether your exact settings would be detected by a Q.24-conformant receiver. Output at 8 kHz for telephone-authentic audio or 44.1 kHz for studio use; repeat the whole sequence up to 10× for loop testing.

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DTMF Tone Generator

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1. Standard 10-Digit North American Dialing Sequence

2. Lossy Line Simulation with Priority Keypad Characters

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