How come when I try to join a halo 3 game on xbox live it wont let me?

[Blake D]

like the the message says that I have an open NAT network or something and this happens when someone invited me to join there game and when it goes to connect to the game it says this.

 

[nutmeg_scouter]

this depends where you live. if oyu live in the UK or europe, you need a stateside address or you need to check you NAT also check on your Xbox 360 dashboard