RTCDTMFSender: tonechange event

The tonechange event is sent to an RTCDTMFSender by the WebRTC API to indicate when DTMF tones previously queued for sending (by calling RTCDTMFSender.insertDTMF()) begin and end.

To determine what tone started playing, or if a tone stopped playing, check the value of the event's tone property.

Examples

This example establishes a handler for the tonechange event which updates an element to display the currently playing tone in its content, or, if all tones have played, the string "<none>".

This can be done using addEventListener():

dtmfSender.addEventListener("tonechange", ev => {
  let tone = ev.tone;
  if (tone === "") {
    tone = "<none>";
  }

  document.getElementById("playingTone").innerText = tone;
}, false);

You can also just set the ontonechange event handler property directly:

dtmfSender.ontonechange = function( ev ) {
  let tone = ev.tone;
  if (tone === "") {
    tone = "<none>"
  }

  document.getElementById("playingTone").innerText = tone;
};

Specifications

Browser compatibility