[pika2000]

So far, from various questions I put on various forums, the answer is no. Only the included SIM card will work on the iPhone. On the other hand, the included SIM card will work on any unlocked/AT&T GSM phone. On the bright side, once activated, you can still use the iPod and/or wifi functions with/without a valid SIM card.

I'll be waiting until Apple wise up and sell unlocked iPhones. So far, the only thing AT&T has done is ****** off some potential customers through failed activations and poor customer service.