Answers an incoming call.
If a function is passed in the handler parameter, that function is called with a call status object to notify of state changes to the phone call.
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.
Handler to register for the call. Executed whenever the call changes state.
digium.phone.answer with util.debug to print call state