Apple Inc., the most profitable handset vendor, and the wireless unit of AT&T Inc. were sued by a customer and accused of misleading buyers of iPhones. Apple, based in Cupertino, California, and AT&T, the second-largest U.S. mobile-telephone company, misled consumers when they said the iPhone would have “multimedia messaging service” capability, the customer said today in a proposed class-action complaint in U.S. District Court in New York. The feature allows users to send pictures to each others’ phones. “MMS functionality was one of the reasons people chose to buy or upgrade” to an iPhone, and it has become “clear that...