The wireless company, which is the exclusive U.S. carrier for the iPhone, made the announcement Thursday. AT&T said it will include iPhone 3GS devices sold through AT&T and Apple.
The iPhone 3GS was released by Cupertino, Calif.-based Apple Inc. in 2009 and had been sold for $99 by AT&T and Apple since the release of the iPhone 4 last June. It can use the same iOS4 software as the iPhone 4.
AT&T, which is based in Dallas, is currently selling refurbished iPhone 3GS' on its website for as low as $49.