Attaches handlers to ongoing-call status changes. Useful if you were unable to attach a handler when the call was created.
The function passed in the handler parameter is called with a call status object to notify of state changes to the phone call.
Handler to register for the call. Executed whenever the call changes state.
Identifier of the call to act on. A call handle can be obtained by observing call events. Information such as this will be passed into the event object.
digium.phone.observeCallEvents with util.debug to print call state