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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.

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support No support No support No support No support No support
Feature Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support 32.0 (32.0) 2.0 No support No support No support

See also

Document Tags and Contributors

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