Using Sprint would have been a lot of trouble for Apple, though. They'd have had to manufacture two iPhone variations – one that works with Sprint's CDMA networ

Using Sprint would have been a lot of trouble for Apple, though. They'd have had to manufacture two iPhone variations – one that works with Sprint's CDMA network, and one that used GSM for every other market in the world. Not that this is impossible, especially if the tradeoffs are right, but it's probably much easier to only have to worry about one type of cell phone chipset.