code: public boolean addHangupListener(CallHangupListener listener)
      {
          boolean callStillUp = true;
  
          if ((this._originatingParty != null && this._originatingParty.isLive())
                  || (this._acceptingParty != null && this._acceptingParty.isLive())
                  || (this._transferTargetParty != null && this._transferTargetParty.isLive()))
              this._hangupListeners.add(listener);
          else
              callStillUp = false;
          return callStillUp;
  
      }
docs: Call this method to get a notification when this call hangs up.
  
  @param listener
  @return true if the hangup listener was added. False if the call has
  already been hungup.