code: public void sessionWillPassivate(SipSessionEvent event) {
  		logger.info("Following sip session just passivated " + event.getSession().getId() + " cause " + ((SipSessionActivationEvent)event).getCause());
  	}
docs: /* (non-Javadoc)
  @see javax.servlet.sip.SipSessionActivationListener#sessionWillPassivate(javax.servlet.sip.SipSessionEvent)