code: public void sessionDidActivate(SipSessionEvent event) {
  		logger.info("Following sip session just activated " + event.getSession().getId() + " cause " + ((SipSessionActivationEvent)event).getCause());
  		if(((SipSessionActivationEvent)event).getCause() == SessionActivationNotificationCause.FAILOVER) {
  			event.getSession().setAttribute(SIP_SESSION_ACTIVATED, "true" );
  		}
  	}
docs: /* (non-Javadoc)
  @see javax.servlet.sip.SipSessionActivationListener#sessionDidActivate(javax.servlet.sip.SipSessionEvent)