HALO CEA PLZ HALP!

Hi, im new and I need your help PLEASE! So I was playing Halo CEA multiplayer, and hell its sooo worth 40 bucks, and it said my NAT rating is closed and I may not be able to hear other players or join games. But I can join games and play fine, but cant hear other players or speak to them. Anyone know how I can open my NAT Rating?

on your network setting checker (the thing that tells you your conection) is shows an online link dosen’t it?

follow it

Here is a great resource on the subject.
http://halo.xbox.com/Forums/yaf_postst38708_How-To-Improve-YOUR-Connection-and-Open-NAT.aspx