code: @Override
  	public void start() throws ProviderDoesNotExistException, SipException {
  		try {
  			sipCache.start();
  		} catch (Exception e) {
  			throw new SipException("Unable to start the SipCache", e);
  		}
  		if(loadBalancerHeartBeatingService != null) {
  			loadBalancerHeartBeatingService.start();
  		}
  		super.start();		
  	}
docs: /*
  (non-Javadoc)
  @see gov.nist.javax.sip.SipStackImpl#start()