Those are X terminal control sequences; from the manual page:
telnet uses at least the HOME, SHELL, DISPLAY, and TERM environment variables. Other
environment variables may be propagated to the other side via the TELNET ENVIRON option.
Check your TERM environment with
it may be linux
(or something else entirely) and you'll need to set it when you get connected to whatever the remote system knows about (xterm
is usually a good starting value). X terminal control sequences are DEC VT102/VT220 compatible and many remotes will recognize a TERM environment of one of those.
Read through the manual page and possibly use one or more of the command line options so telnet
will "talk nice" with the remote.
Another option is to use ssh
(if it's a Unix/Linux box on the other end) and you'll probably have a little better luck.
Hope this helps some.