code: public void passivate() {
          // Notify ActivationListeners
      	SipApplicationSessionEvent event = null;
      	if(this.sipApplicationSessionAttributeMap != null) {
  	        Set<String> keySet = getAttributeMap().keySet();
  	        for (String key : keySet) {
  	        	Object attribute = getAttributeMap().get(key);
  	            if (attribute instanceof SipApplicationSessionActivationListener) {
  	                if (event == null)
  	                	event = new SipApplicationSessionActivationEvent(this, SessionActivationNotificationCause.PASSIVATION);
  	                try {
  	                    ((SipApplicationSessionActivationListener)attribute)
  	                        .sessionWillPassivate(event);
  	                } catch (Throwable t) {
  	                    logger.error("SipApplicationSessionActivationListener threw exception", t);
  	                }
  	            }
  			}
  	    }
      }
docs: Perform the internal processing required to passivate
  this session.