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The RTCDTMFSender interface provides a mechanism for transmitting DTMF codes on a WebRTC RTCPeerConnection. You gain access to the connection's RTCDTMFSender through the RTCRtpSender.dtmf property on the audio track you wish to send DTMF with.

The primary purpose for WebRTC's DTMF support is to allow WebRTC-based communication clients to be connected to a public-switched telephone network (PSTN) or other legacy telephone service, including extant voice over IP (VoIP) services. For that reason, DTMF can't be used between two WebRTC-based devices, because there is no mechanism provided by WebRTC for receiving DTMF codes.


RTCDTMFSender.toneBuffer Read only
A DOMString which contains the list of DTMF tones currently in the queue to be transmitted (tones which have already been played are no longer included in the string). See toneBuffer for details on the format of the tone buffer.

Event handlers

An EventHandler to handle the tonechange event, which is sent each time an outbound tone starts or finishes playing.


Given a string describing a set of DTMF codes and, optionally, the duration of and inter-tone gap between the tones, insertDTMF() starts sending the specified tones. 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.




Specification Status Comment
WebRTC 1.0: Real-time Communication Between Browsers
The definition of 'RTCDTMFSender' in that specification.
Candidate Recommendation  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes ?52 No ? ?
toneBuffer Yes ?52 No ? ?
ontonechange Yes ?52 No ? ?
insertDTMF Yes ?52 No ? ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No Yes ?52 ? ? ?
toneBuffer No Yes ?52 ? ? ?
ontonechange No Yes ?52 ? ? ?
insertDTMF No Yes ?52 ? ? ?

See also

Document Tags and Contributors

 Contributors to this page: fscholz, Sheppy
 Last updated by: fscholz,