Another part of that deal was that the phones were unsubsidized, and the data plan was a lot cheaper than AT&T's other data plans ($20 for unlimited, everything

Another part of that deal was that the phones were unsubsidized, and the data plan was a lot cheaper than AT&T's other data plans ($20 for unlimited, everything else was $30 at the time). I am pretty sure that Apple sacrificed all of the monthly revenue from AT&T when they moved to the more conventional US subsidy model with the iPhone 3G.