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

The onerror event handler of the TelephonyCall interface is a reference to a function to be called when the call does not succeed due to error. This is being obsoleted as it is very similar to TelephonyCall.ondisconnected, but semantically more narrow and therefore not as useful.

The event handler is called with a CallEvent as its only parameter.


// Telephony object
var tel = navigator.mozTelephony;

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

  call.onerror = function(e) {
    console.log('Your call has failed with an error ' +;


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