Original Article available here: http://faq.en.playstation.com/app/answers/detail/a_id/168
If you are able to connect to the Internet but cannot get into Sony Computer Entertainment Europe's (SCEE) game servers or network, it may be a firewall issue. Here are the TCP and UDP Port numbers you will need to connect to SCEE game servers. If you need port numbers for games published by other companies, you will need to contact them directly for additional information.