code: public void setTTLParam(int ttl) {
  		try {
  			getSipURI().setTTLParam(ttl);
  			super.parameters.put(TTL, "" + ttl);
  		} catch (InvalidArgumentException e) {
  			logger.error("invalid argument", e);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipURI#setTTLParam(int)