SipHandler simpleHandlerJustForward200OK = new SipHandler() {
            @Override
            DefaultSipMessage apply(DefaultSipMessage defaultSipMessage) {
                if(defaultSipMessage instanceof DefaultSipRequest){
                    DefaultSipRequest defaultSipRequest = (DefaultSipRequest) defaultSipMessage

                    DefaultSipResponse response200OK = defaultSipRequest.createResponse(SIPResponse.OK)

                    return response200OK
                }
            }
        }

SipConsumer sipConsumer = new SipConsumer() {
            @Override
            void send(DefaultSipMessage defaultSipMessage) {
                ConnectionManager connectionManager = ConnectionManager.getInstance()

                String remoteHost = "";
                int remotePort = 0;
                String remoteTransport = "";
                ChannelHandlerContext targetCtx = null;

                SIPMessage message = defaultSipMessage.getRawSipMessage()

                if(defaultSipMessage.getRawSipMessage() instanceof SIPRequest){
                    RouteList routeList = defaultSipMessage.getRawSipMessage().getRouteHeaders();

                    if(routeList != null && routeList.size() !=0){
                        // Contains Route header
                        // TODO: Find connection using 'Route' Header
                        RouteHeader routeHeader=(RouteHeader) defaultSipMessage.getRouteHeaders().getFirst();
                        SipUri routeUri=(SipUri) routeHeader.getAddress().getURI();

                        remoteHost=routeUri.getHost();
                        remotePort=routeUri.getPort();
                        remoteTransport=routeUri.getTransportParam();
                    }
                    else{
                        // No Route header
                        // Using request-uri to find target connection
                        SIPRequest sipRequest=(SIPRequest) message;
                        SipUri requestUri=(SipUri) sipRequest.getRequestURI();

                        remoteHost=requestUri.getHost();
                        remotePort=requestUri.getPort();
                        remoteTransport=requestUri.getTransportParam();
                    }
                }
                else{
                    // Response

                    SIPResponse sipResponse=(SIPResponse) message;

                    Via topVia = sipResponse.getTopmostVia();
                    remoteHost = topVia.getReceived();
                    remotePort = topVia.getRPort();

                    remoteTransport = topVia.getTransport().toLowerCase();
                }

                targetCtx = connectionManager.getConnection(remoteHost, remotePort, remoteTransport);

                if(targetCtx != null){
                    ChannelFuture cf;
                    if(Transport.TCP.getValue().equals(remoteTransport)){
                        cf = targetCtx.writeAndFlush((Unpooled.copiedBuffer(message.toString(), CharsetUtil.UTF_8)));
                    }
                    else if(Transport.UDP.getValue().equals(remoteTransport)){
                        cf = targetCtx.writeAndFlush(new DatagramPacket(
                                Unpooled.copiedBuffer(message.toString(), CharsetUtil.UTF_8),
                                new InetSocketAddress(remoteHost, remotePort)));
                    }
                    else if(Transport.WSS.getValue().equals(remoteTransport)){
                        cf = targetCtx.writeAndFlush(new TextWebSocketFrame(message.toString()));
                    }
                }
                else {
                }
            }

            @Override
            void accept(DefaultSipMessage defaultSipMessage) {

                // Do Some stuffs here

                // Send Message to target!
                send(defaultSipMessage)
            }
        }

ServerFactory serverFactory = new ServerFactory()
        SipServer sipServer = serverFactory
                .host(givenServerListenHost)
                .port(givenServerListenPort)
                .transport(givenServerTransport)
                .sipMessageHandler(simpleHandlerJustForward200OK)
                .sipMessageConsumer(sipConsumer)
                .build()

        sipServer.runSync()