Tiscali are known to block p2p in some area's and latley alot more people are comming to the forums with the same problem, with Tiscali being their ISP...
What you could try is Port Forwarding, so if you could provide your modem/router details we could get the instructions and go from there...
You will find the info needed if you turn your modem upside down it should all be underneath it...
