Originally Posted by anotherbrian

I use AOL's instant messenger port (5190?).

My small town cable company blocks 80, 443, and all the other well known services/ports (telnet, ftp, ssh) for their home user level of service. Fortunately my work's outgoing firewall rules are published, and I've been able to find a few ports that will work for both (all instant messaging related).

[going deeper into the technical:] I have found that our VPN gateways (we've got at least two dozen around the world) aren't configured consistently, and some will forward traffic into the intranet and out the firewalls, while others will leave it all outside with fewer restrictions.