I have not seen it specifically mentioned, but which SIM card(s) does the iPhone actually support? Currently, iPhone is more than likely shipped with Cingular SIM cards. When Cingular bought AT&T, they no longer issued AT&T SIM cards and issued their own cards. Now since the company has been renamed, they still issue Cingular SIM cards, but everyone knows as AT&T SIM cards.

AT&T had their own SIM cards pre-Cingular which are not compatible with locked Cingular phones and new AT&T phones. On the iPhone, will an AT&T SIM card work with it? I have a company phone which has an AT&T SIM card which will only work on AT&T pre-Cingular phones.

Lastly, will the AT&T data plan work on the iPhone? I have seen lots of people ask this, but noone has answered it.