The telnet client isn’t part of the default install on Server 2008 R2, (although it can be an added feature) and telnet makes it very easy to confirm whether or not you are able to connect to a server on a given port. Powershell to the rescue! If you need to test port connectivity you can do this with the following Powershell command:-
$socket = new-object System.Net.Sockets.TcpClient(“188.8.131.52”, “5723”)
Replace the values in quotes with the actual IP address and port number.