[fleurya]

I've been reading up from a lot of forums, especially Howardforums.com where they live and breathe phones. The deal is that any AT&T SIM card will work in the iPhone, but only if it's activated with an iPhone plan. You can't take your SIM card activated under another plan and use it in the iPhone. However, you can take a SIM card activate with the iPhone and use it in another AT&T or unlocked GSM phone.

AT&T does not allow any other plans or discount programs, such as corporate discounts, with the iPhone, not even for iPhone related accessories. This is what I've heard from people with first hand experience.