Code server I have server listen on port 1450:

//Using UDP sockets

  clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            EndPoint ourEP = new IPEndPoint(IPAddress.Any, 1450);
            //Listen asynchronously on port 1450 for coming messages (Invite, Bye, etc).
            clientSocket.Bind(ourEP);
            //Receive data from any IP.
            EndPoint remoteEP = (EndPoint)(new IPEndPoint(IPAddress.Any, 0));

            byteData = new byte[1024];
            //Receive data asynchornously.
            clientSocket.BeginReceiveFrom(byteData,
                                       0, byteData.Length,
                                       SocketFlags.None,
                                       ref remoteEP,
                                       new AsyncCallback(OnReceive),
                                       null);

but code on not open port 1450 and client connect:

  otherPartyIP = new IPEndPoint(IPAddress.Parse(txtCallToIP.Text), 1450);
                otherPartyEP = (EndPoint)otherPartyIP;

When i run code client and server in lan network it's ok. but run over network i check port 1450 in lan not open. tell me how open port 1450 in code server? thanks