AT&T cellphone network question?

Okayy so I just got a new phone and renewed my two year plan with AT&T :) but the problem is, I'm moving to asia in one year. AT&T in my area won't do one year contracts. I heard that AT&T is a worldwide network. so does that mean that i could still use my phone when i move to asia and just get a new number without cancelling my contract? Or do i have to cancel my contract when i move? :( thanks in advance :) and please, no rude, useless comments.