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


A reference to a function to be called to handle the Telephony API's busy event. This event occurs when the call receives a busy signal from the phone network. The event handler is called with a CallEvent as its only parameter.


instanceOfTelephonyCall.onbusy = funcRef;

Where funcRef is a function to be called when the busy event occurs. These events are of type CallEvent.


This is a non standard implementation, but it is discussed at W3C as part of the System Application Working Group.

Specification Status Comment
Web Telephony Draft Editor Draft (WIP).

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) IE Mobile Opera Mobile Safari Mobile
Basic support No support 12.0 (12.0) No support No support No support

See also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, teoli, fscholz, jsx, kscarfone, Jeremie, Sheppy
 Last updated by: chrisdavidmills,