Apple iPhone Service + Data Plans
Apple and AT&T (formerly Cingular) have signed a five year exclusivity agreement.
If you're on another American carrier, you'll have to wait for an unlocked version of the IPhone to come along, or wait 5 years.
The iPhone will be available for other networks in Europe starting Q4 2007.
Yes, the iPhone will work overseas, and not just in Europe and Asia. The iPhone is a GSM (Global System for Mobile communication) phone. GSM, which uses narrowband TDMA, was first introduced as a standard in 1991 and is now in place in over 100 countries.
Access to receive and place calls from outside the United States will require additional services from AT&T/Cingular, which you will need to arrange with them before your phone will operate in such a fashion, but the phone is perfectly capable for worldwide use.
Up until this point there's been little reason to believe that the iPhone would support Cingular's network. Why Apple and Cingular would release a next generation device that was a generation behind in wireless connectivity has left some people scratching their heads. Recently, rumors have started circulating that the iPhone may surprise us again. The New York Times recently reported: