farbot.com

Some individuals have had difficulty getting their voice traffic to work in on online game. Some have reported that having the following ports forwarded from your router to your PS3 will help with that, but this PlayStation support page mentions them only in reference to the PSP:

TCP Ports: 10070 through 10080.
UDP Port: 10070.

The page goes on to mention that "if you need port numbers for games published by third-party companies, you will need to contact them directly for additional information."

A similar PS2 online gaming page also mentions these ports.