Been having a look. It seems as the xbox v PS3 online play comes down to the ports being used. Did some searching and these are the ports that should be opened or forwarded for you PS3:

Application: CODBOPS3 External port: 80 Internal port: 80 Protocol: TCP

Application: CODBOPSA External port: 81 Internal port: 81 Protocol: TCP/UDP

Application: CODBOPSB External port: 443 Internal port: 443 Protocol: TCP

Application: CODBOPSC External port: 3074 Internal port: 3074 Protocol: TCP/UDP

Application: CODBOPSD External port: 3075 Internal port: 3075 Protocol: UDP

Application: CODBOPSE External port: 3478 Internal port: 3478 Protocol: UDP

Application: CODBOPSF External port: 5223 Internal port: 5223 Protocol: TCP


I did something similar for NHL on the PS3 and it worked. Just remember to open these ports for the PS3 only. Specify an IP for the PS3 then in your router open/forward the ports for that IP address.

These are the ports for Modern warfare 2:

Application: CODMW2 External port: 1500 Internal port: 1500 Protocol: UDP

Application: CODMW2A External port: 3005 Internal port: 3005 Protocol: UDP

Application: CODMW2B External port: 3101 Internal port: 3101 Protocol: UDP

Application: CODMW2C External port: 28960 Internal port: 28960 Protocol: UDP

Application: CODMW2D External port: 27015 Internal port: 27015 Protocol: TCP