RTCDTMFSender: insertDTMF() method

The insertDTMF() method on the RTCDTMFSender interface starts sending DTMF tones to the remote peer over the RTCPeerConnection.

Sending of the tones is performed asynchronously, with tonechange events sent to the RTCDTMFSender every time a tone starts or ends.

As long as the connection is active, you can send tones at any time. Calling insertDTMF() replaces any already-pending tones from the toneBuffer. You can abort sending queued tones by specifying an empty string ("") as the set of tones to play. Since insertDTMF() replaces the tone buffer, in order to add to the DTMF tones being played, it is necessary to call insertDTMF with a string containing both the remaining tones (stored in the toneBuffer) and the new tones appended together.


insertDTMF(tones, duration)
insertDTMF(tones, duration, interToneGap)



A string containing the DTMF codes to be transmitted to the recipient. Specifying an empty string as the tones parameter clears the tone buffer, aborting any currently queued tones. A "," character inserts a two second delay.

duration Optional

The amount of time, in milliseconds, that each DTMF tone should last. This value must be between 40 ms and 6000 ms (6 seconds), inclusive. The default is 100 ms.

interToneGap Optional

The length of time, in milliseconds, to wait between tones. The browser will enforce a minimum value of 30 ms (that is, if you specify a lower value, 30 ms will be used instead); the default is 70 ms.

Return value

None (undefined).


InvalidStateError DOMException

Thrown if the DTMF tones couldn't be sent because the track has been stopped or is in a read-only or inactive state.

InvalidCharacterError DOMException

Thrown if one or more of the characters in tones is not valid DTMF (0-9, A-Z, # or ,).




WebRTC: Real-Time Communication in Browsers
# dom-RTCDTMFSender-insertDTMF

Browser compatibility

BCD tables only load in the browser

See also