Nokia held on for dear life with the No. 3 smartphone at AT&T. Despite reports of mediocre sales overall for the Lumia series, the 900 – an AT&T exclusive in the U.S. – has managed to stay in the top three at America's second-largest wireless carrier since its launch in April. The Windows-based device benefitted from a price cut in July that made it a budget phone (just $50) despite some pretty powerful specs, including LTE connectivity.