Normally, use of telnet to connect to a server is not recommended, as it is inherently insecure. In place of telnet, it is recommended to use SSH. SSH comes in 2 flavors. SSH-1, now defunct, due to security issues, and SSH-2. Always, make sure you use SSH protocol version 2 (SSH-2) to connect to your servers, at the shell prompt.
$ ssh user@hostname <enter>
$ ssh firstname.lastname@example.org <enter>
SSH is free for Linux distributions. For Windows, you will need to use putty, to connect from the Windows machine to any server that runs the SSH service.