code: public URI getSubscriberURI() {
  		if(!isValid()) {
  			throw new IllegalStateException("the session has been invalidated");
  		}
  		if (this.subscriberURI == null)
  			throw new IllegalStateException("Subscriber URI is only available for outbound sessions.");
  		else {
  			try {
  				return sipFactory.createURI(subscriberURI);
  			} catch (ServletParseException e) {
  				throw new IllegalArgumentException("couldn't parse the outbound interface " + subscriberURI, e);
  			}
  		}
  	}
docs: {@inheritDoc}