If they block p2p, then you might be a bit stuffed...I doubt changing ports would help. Check the thread below, you might find something to help but no guarantees!
http://www.gnutellaforums.com/showth...threadid=32882

Switching ISP is the obvious fix but it depends on whether you signed a contract for a specified term...you might end up having to pay a fee to get out of the contract.
If you do go looking for a new ISP, check their Acceptable Use Policy or Fair Access Policy (sometimes this info is found in general Terms & Conditions too). That will often tell you whether the ISP is anti p2p. Google the ISP & search for these policies, often the customer service people won't give you a straight answer or aren't aware that it's going on:wink:

You could also add WHTV to this thread of providers who block/filter p2p...might help someone in the future.
http://www.gnutellaforums.com/showth...threadid=33712