code: public void sessionWillPassivate(SipApplicationSessionEvent event) {
  		logger.info("Following sip application session just passivated " + event.getApplicationSession().getId() + " cause " + ((SipApplicationSessionActivationEvent)event).getCause());
  
  	}
docs: /* (non-Javadoc)
  @see javax.servlet.sip.SipApplicationSessionActivationListener#sessionWillPassivate(javax.servlet.sip.SipApplicationSessionEvent)