A great workaround if telnet is not installed on MS server but PowerShell is available. Just open PowerShell and use the following command to test if port is accessible.
Test-NetConnection -ComputerName SERVERNAME -InformationLevel “Detailed”
The Test-NetConnection cmdlet displays diagnostic information for a connection. It supports ping test, TCP test, route tracing, and route selection diagnostics. Depending on the input parameters, the output can include the DNS lookup results, a list of IP interfaces, IPsec rules, route/source address selection results, and/or confirmation of connection establishment.
Testing comment