=== DOM API ===
We can access the phone functionality simply through navigator.mozTelephony. Once we have a reference to that object, we can start placing and recieving calls by the API below. interface nsIDOMTelephony: nsIDOMEventTarget
{
nsIDOMTelephonyCall dial(in DOMString number);
readonly attribute DOMString number;
// "dialing", "alerting", "busy", "connecting", "connected", "disconnecting", // "disconnected", "incoming", "holding", "held", "resuming"
readonly attribute DOMString state;
// functions to mediate a call.
void answer();
void hangUp();
//make a "connected" call into "held"
void hold();
//make a "held" call back to "connected"
void resume();