Telnet is a simple method of checking whether a specific TCP port is available from a client machine. From a machine that is having trouble contacting a server, use the following steps to verify connectivity to the Registrar service:
1. Open a command prompt.
2. Type the following command:
telnet <Director pool FQDN> 5061
If the window goes blank and only a flashing cursor is seen, it means the connection was successful and the port can be contacted without issue. If the connection fails, an error is returned. Check that the services are running on the Director and that no firewalls are blocking the traffic.
The Telnet client has not installed by default since Windows Vista and Windows Server 2008. On a desktop operating system, it ...