Kinda sorta. A tangled web of mergers led to the near-complete reassembly of the parts of AT&T by the time the iPhone actually shipped. It was announced on Cingular, but given that Cingular was always a joint venture of two of the RBOCs anyway, you can roughly round that to AT&T even if the "You Will" campaign was made by the smaller AT&T Long Distance company (since it was made after the Bell System breakup split the RBOCs off from "AT&T").