Is just iPhone tied to AT&T, or all Apple phones?

I wonder how Apple's deal with AT&T works for future iPhone models... for example, if Apple comes out with a new iPhone called the "iPhone 3G", is it possible for Apple to sell it without being tied to AT&T, since it isn't exactly an "iPhone"?

Or is Apple stuck with AT&T for all future phones they may release for the duration of their agreement?

Written on April 25, 2008