code: public void setUserParam(String user) {
  		try {
  			getSipURI().setUserParam(user);
  			super.parameters.put(USER, user);
  		} catch (ParseException e) {
  			logger.error("error setting parameter ", e);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipURI#setUserParam(java.lang.String)