FSClient.Call.UpdateCallState C# (CSharp) Méthode

        private void UpdateCallState(CALL_STATE new_state)
        {
            UpdateCallState(new_state, active_call);
        }

 private static void HandleCustomEvent(FSEvent evt, string uuid)
 {
     if (evt.subclass_name == "portaudio::ringing")
     {
         Utils.DebugEventDump(evt);
         if ((from c in calls where c._leg_a_uuid == uuid && c.call_ended == false select c).Count() > 0)                //only care about first ring
         {
             return;
         }
         Call call = new Call();
         call.SetCallInfoFromEvent(evt);
         String gw_id = (from c in channels where c.Key == call.leg_b_uuid select c.Value.gateway_id).SingleOrDefault();
         call.account = (from a in Account.accounts where a.gateway_id == gw_id select a).SingleOrDefault();
         calls.Add(call);
         call.UpdateCallState(CALL_STATE.Ringing, active_call ?? call);
     }
     else if (evt.subclass_name == "portaudio::makecall")
     {
         Utils.DebugEventDump(evt);
         if (evt.get_header("fail") == "true")
         {
             MessageBox.Show("Make Call failed!!!, came from portaudio not sure why");
             return;
         }
         Call call = new Call();
         call.is_outgoing = true;
         call.SetCallInfoFromEvent(evt);
         if (call.other_party_number == "fsc_conference")
         {
             call.visibility = Visibility.Collapsed;
             Conference.instance.our_conference_call = call;
             call.is_conference_call = true;
         }
         calls.Add(call);
         call.UpdateCallState(call.is_conference_call ? CALL_STATE.Answered : CALL_STATE.Ringing, call);
     }
     else if (evt.subclass_name == "portaudio::callheld" || evt.subclass_name == "portaudio::callresumed")
     {
         String paid_str = evt.get_header("variable_pa_call_id");
         if (String.IsNullOrEmpty(paid_str))
         {
             return;
         }
         int  portaudio_id = Int32.Parse(paid_str);
         Call call         = (from c in calls where c.portaudio_id == portaudio_id && c.call_ended == false select c).SingleOrDefault();
         if (call == null)
         {
             return;
         }
         if (evt.subclass_name == "portaudio::callresumed")
         {
             call.UpdateCallState(CALL_STATE.Answered, call);
         }
         else
         {
             call.UpdateCallState(call.state == CALL_STATE.Ringing ? CALL_STATE.Hold_Ringing : CALL_STATE.Hold, call == active_call ? null : active_call);
         }
     }
 }