====== onTalking() ======
wrtc.onTalking() is an event function called when a call has been established and media starts to flow between the callers. You are "on the phone".

You can use this event to enable how your client should look during a call. You can display "Hang up", "Transfer", etc buttons user can do with the call.

===== Occurs =====
wrtc_kit has received incoming media (video and/or sound).

===== Arguments =====
wrtc.onTalking(obj)
  * obj - call object raising the event

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

===== Example =====
<code>
wrtc.onTalking = function(obj) {
    stus.innerHTML = "Connected to " + obj.getPartner() +
      " <input type=\"button\" value=\"Hang up\" onclick=\"" + obj.nam + ".hangup()\" />";
}
</code>