Squid and non standard ports

Hi everyone!
Hi have a question for you.
In my company there is a squid proxy behind a firewall, serving a lot of
users.
Some users need to connect to some services using non standard port within
the internet browser, but squid block all the traffic other than port 80,
21, ecc.

Is there any way to permit users connection to these services?

Thanks


simone@replay.it