To properly get into a 7.0 Switch, you will need to use SSH, which will ask for the RSA token verification, from there, you can login to the Linux Base (if co-res) or directly to the VxWorks. If you are running linux, then just issue command cslogin to get into the Call Server.
From 6.0+ telnet is usually disabled by default, but can be fixed by issuing harden telnet off (or something similar)