The IRC networks you connect to may have non-standard ports available for you to connect to. If your ISP blocked IRC ports, they most likely blocked 6660-6670, and didn't block any non-standard ports that your IRC network may offer. Finding out what those ports are may be a problem, but if your IRC network has a website, that would be a good place to start.
* Warning: bypassing your ISPs restrictions may result in your internet being disconnected for breaking the User Agreement that you acknowledged when you signed up.
-genius_at_work
