====== onIncomingCall() ======
wrtc.onIncomingCall() is an event function called when an incoming call attempt is received, someone is calling you.

<WRAP center round important 100%>
You must write your own wrtc.onIncomingCall() function to be able to answer incoming calls.
</WRAP>

Usually your wrtc.onIncomingCall() function should notify user of incoming call (eg play a "telephone ringing" sound) and display Accept/Deny buttons.

===== Arguments =====
wrtc.onIncomingCall(obj)
  * obj - [[ixnx:wrtc:js:api:call:start|call object]] that raised the event

===== Return value =====
Ignored.

===== Example =====
<code>
wrtc.onIncomingCall = function(obj) {
    status.innerHTML = "Call from " + obj.getPartner() +
      " <input type=\"button\" value=\"Answer\" onclick=\"" + obj.nam + ".answerCall()\" />" +
      " <input type=\"button\" value=\"Deny\" onclick=\"" + obj.nam + ".denyCall()\" />";
}
</code>