Choose a Key or Sequence
Press a keypad button for one pair, or enter digits, star, hash, and optional A-D symbols.
Touch-tone workspaceLocal audio
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Selected keyNoneChoose a keypad symbol
Show A-D keys
Valid symbols: 0-9, *, #, and optional A-D.
Browser audio signal toolkit
DTMF Tone Generator
Press a telephone keypad symbol or schedule a short sequence using the standard low-group and high-group frequency pairs, with all synthesis and export performed locally.
What Are DTMF Tones?
Dual-tone multi-frequency signaling represents a symbol with two simultaneous sine frequencies: one selected from a low group and one from a high group. The familiar digits, star, and hash occupy a 4 by 3 keypad, while A through D use a fourth column that is less common on consumer phones. This DTMF tone generator implements all 16 nominal pairs defined by the matrix in ITU-T Recommendation Q.23 and displays both component frequencies whenever a key is selected.
The DTMF tone generator is intended for education, audio demonstrations, development checks, and creation of short local reference files. It is not a telecom certification instrument. A receiving system may depend on tolerances, relative component levels, duration, gaps, distortion, channel processing, and network behavior beyond the nominal pair. Sound from ordinary speakers or a compressed communications path can differ materially from the samples generated inside the browser.
Three simple steps
How to Get Started
Use this dtmf tone generator deliberately: set the signal, begin quietly, and interpret only what the workflow can actually show.
Set Timing and Level
Choose a conservative digital output, tone duration, and gap duration for the sequence.
Play, Inspect, or Export
Review each low/high pair, stop immediately, copy the sequence, or create a local mono WAV.
How the DTMF Frequency Matrix Works
The low rows are 697, 770, 852, and 941 Hz. The high columns are 1209, 1336, 1477, and 1633 Hz. Key 5 combines 770 with 1336 Hz; key 0 combines 941 with 1336 Hz; and key D combines 941 with 1633 Hz. Selecting exactly one row and one column gives 16 distinct symbols from only eight oscillators. The generator uses equal digital gain for both components and a shared fade envelope to avoid abrupt edges.
Using the Keypad
The twelve everyday telephone keys remain visible by default. Expanding the advanced area exposes A, B, C, and D without crowding the common workflow. Pressing a button plays its pair briefly and updates the selected-symbol readout. Playback begins only after that user action. The button is keyboard accessible, and status text reports the same symbol and frequencies so the state is not communicated by sound or color alone.
Building a DTMF Sequence
The sequence field accepts the valid symbols and ignores common visual separators such as spaces, commas, periods, and hyphens. Other characters produce a direct validation message and prevent sequence playback or export until corrected. Tone duration controls how long each pair remains active; gap duration inserts silence between symbols. The Web Audio engine schedules the complete sequence against the audio context clock, which is more stable than treating a chain of DOM timers as the audible source.
DTMF vs a General Dual Tone Generator
A general dual tone generator lets you choose arbitrary frequencies, waveforms, stereo positions, and relative levels. This DTMF tone generator deliberately restricts each symbol to the standard nominal sine pair and adds keypad semantics plus sequence timing. Use the general tool to study two-frequency interactions. Use this page when the identity of DTMF symbols and their matrix allocation is the actual subject. Neither page promises successful recognition by a telephone or access-control system.
Common Legitimate Uses
Useful examples include teaching how row-and-column signaling works, checking that an application maps keypad symbols correctly, creating a short test fixture for software under your control, or hearing the difference between pairs. The tool is not designed to automate calls, bypass authentication, or interact with systems without authorization. Keep sequences short and use them only in lawful, controlled environments where you are permitted to generate the signals.
Timing and Playback Limitations
The requested durations are browser scheduling targets, not certified measurements at a receiver. Audio buffering, suspended tabs, wireless devices, operating-system effects, and capture or transmission paths can alter onset, spacing, and level. The WAV export is more repeatable as a digital file, but downstream playback can still modify it. A compliance evaluation requires suitable measurement equipment, defined tolerances, and the complete applicable specification rather than a successful browser demonstration.
Browser Audio and Hardware Limits
All DTMF frequencies sit within the ordinary voice-frequency region, yet consumer equipment may apply equalization, echo control, noise reduction, compression, or automatic gain. Those processes can change twist and introduce distortion. This page reports nominal source frequencies only. Digital output percentage is not acoustic SPL, electrical line level, or received power. Begin quietly, avoid holding tones near your ear, and use the prominent Stop control whenever playback is no longer needed.
Clear answers
Frequently Asked Questions
Which frequencies does key 5 use?
Key 5 combines the 770 Hz low-group row with the 1336 Hz high-group column.
What are the A-D buttons?
They form the fourth 1633 Hz column of the 4 by 4 matrix. They are valid DTMF symbols but are uncommon on household telephone keypads.
Will every phone system recognize these tones?
No. Recognition also depends on timing, levels, distortion, processing, and the receiving system. This browser tool is not a certification source.
Does sequence export upload anything?
No. The PCM WAV is synthesized and downloaded locally in the browser.