Well okay.. When my friend tests his xbox360 for live and everything is okay but his NAT it says NAT Strict when he tests it and he's connected straight to his DSL modem so there's nothing in between so in cause you're wondering this is the setup

[]---X not []----{}----X the {} stands or router, [] stands for modem and X stands for the xbox360... so its the first setup I put in there... so nothing inbetween the modem and xbox 360...

Now the modem brand and model is unknown and along with the ISP so lets pretend it's some generic brand and model ADSL modem... now what would he have to do to fix this? Could it also be possible that his ISP is running him through a firewall on their end?...