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

The secondNumber read-only property of the TelephonyCall interface indicates the second phone number in the case of a CDMA network where you have a 2nd waiting call. Replaced by TelephonyCall.SecondId in Firefox OS 2.0+.


var secondCalledNumber = myCall.secondNumber;


A DOMString.


// Telephony object
var tel = navigator.mozTelephony;

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

  // Get the first and second numbers of the incoming call
  console.log(incomingCall.number + ', ' + incomingCall.secondNumber);

  // 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 12.0 (12.0) [1] 1.0.1 [1] No support No support No support

[1] Replaced by TelephoneCall.secondId in Firefox OS 2.0 (Gecko 32.)

See also

Document Tags and Contributors

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