As Sam described, telnet is used to connect to a remote computer and run whatever programs are available on your account on that machine. For more precise information, see:
http://www.wikipedia.org/wiki/Telnet
Take note the information near the bottom concerning telnet's security problems and the solution, namely, SSH (versions 1 & 2). See:
http://www.wikipedia.org/wiki/SSH/
For a DOS SSH1/2 solution, see:
http://sshdos.sourceforge.net/
I've used both SSH 1 & 2 for DOS with no problems.
may this reach you smiling! david