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

The secondId read-only property of the TelephonyCall interface indicates the second caller's id (usually their phone number) in the case of a CDMA network where you have a 2nd waiting call.


var secondCallerId = myCall.secondId;


A TelephonyCallId object.


// Telephony object
var tel = navigator.mozTelephony;

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

  // Get the first and second caller ids of the incoming call
  console.log( + ', ' + incomingCall.secondId);

  // Answer the call


Specification Status Comment
Web Telephony Draft Draft.

Browser compatibility

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

Supported in Firefox OS 2.0.

See also

Document Tags and Contributors

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