This API is available on Firefox OS for internal applications only.

The oncallschanged property of the Telephony interface specifies an event listener to receive callschanged events. These events occur when the list of ongoing calls, as indicated by TelephonyCallGroup.calls, changes.


myTelephonyCallGroup.oncallschanged = function() { ... };

These events are of type CallEvent.


// Telephony object
var tel = navigator.mozTelephony;

// Make two calls; assume they are both answered
var call1, call2;
tel.dial(number1).then(call => call1 = call);
tel.dial(number2).then(call => call2 = call);

// Add both calls to the conference call
// Two entries will appear in conference.calls (call1, call2)
// but nothing in tel.calls
var conference = tel.conferenceGroup;
conference.add(call1, call2);

conference.oncallschanged = function() {
  // When call list changes, do something


Specification Status Comment
Web Telephony Draft Draft

Browser compatibility

For obvious reasons, support is primarily expected on mobile browsers.

Supported in Firefox OS 1.0.1.

See also

Document Tags and Contributors

 Contributors to this page: fscholz, chrisdavidmills, teoli
 Last updated by: fscholz,