code: public boolean sendUnidirectionalRequest(Request request, boolean viaProxy) {
      initErrorInfo();
  
      if (viaProxy == true) {
        if (addProxy(request) == false) {
          return false;
        }
      }
  
      try {
        parent.getSipProvider().sendRequest(request);
        return true;
      } catch (Exception ex) {
        setException(ex);
        setErrorMessage("Exception: " + ex.getClass().getName() + ": " + ex.getMessage());
        setReturnCode(EXCEPTION_ENCOUNTERED);
        return false;
      }
    }
docs: This sendUnidirectionalRequest() method sends out a request message with no response expected.
  The Request object passed in must be a fully formed Request with all required content, ready to
  be sent.
  
  @param request The request to be sent out.
  @param viaProxy If true, send the message to the proxy. In this case a Route header is added by
  this method. Else send the message as is. In this case, for an INVITE request, a route
  header must have been added by the caller for the request routing to complete.
  @return true if the message was successfully sent, false otherwise.