Looking for ssh tunnelling software, to convert telnet traffic.

Hi
Within our internal network, we have a test system that allows several client machines to log in to a Server using telnet, port 23 – The clients have a terminal emulation application installed to allow this, but it doesn?t support SSH ? I would like to know if there is an application that has the potential to convert telnet to SSH via tunnelling ? It?s imperative we keep the existing emulation software.
Cheers
> ST.