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

The Telephony interface of the Web Telephony API provides support for dialing, answering, and managing phone calls on a device with telephony support.

Properties Read only
A TelephonyCall object indicating the call that is currently active. The active call is the one receiving input from the microphone and any tones generated using the Telephony.startTone() method.
Telephony.calls Read only
An array of TelephonyCall objects, one for each call that is currently connected.
Telephony.conferenceGroup Read only
A TelephonyCallGroup object, allowing programmatic control over a multi-person call/conference call.
Set to true to mute the microphone or false to enable the microphone.
Telephony.ready Read only
Provides an asynchronous notification that the Telephony object has been initialized successfully.
Set to true to enable the speakerphone functionality or false to disable it.

Event Handlers

A handler for the callschanged event; this CallEvent event is sent whenever the calls list changes.
A handler for the incoming event; this CallEvent is sent whenever a new call is incoming.
A handler for the remoteheld event; this CallEvent is sent whenever a remote party (e.g. the person you called) puts the call on hold.
A handler for the remoteheld event; this CallEvent is sent when a remote party (e.g. the person you called) resumes a call previously put on hold.

Obsolete event handlers

A handler for the ready event; this CallEvent is sent when the telephony object is initialized. This was implemented in Firefox OS 2.1, but obsoleted by the promise-based Telephony.ready property in Firefox OS 2.2.


Dials the specified phone number or MMI code.
Dials the specified emergency phone number.
Designates the calling app as the owner of the telephony calls from the AudioChannel policy.
Generates and sends specific DTMF tones.
Begins generating the specified DTMF tone.
Stops generating the currently sounding DTMF tone.


// Telephony object
var tel = navigator.mozTelephony;

// Place a call
tel.dial("123456789").then(function(call) {

// Receive a call
tel.onincoming = function (e) {
  var incomingCall =;

  // Get the id/number of the incoming call

  // Answer the call


Specification Status Comment
Web Telephony Draft Draft

Browser compatibility

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

Supported on Firefox OS 1.0.1.
ownAudioChannel() added in Firefox OS 2.5

See also

Document Tags and Contributors

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