The top 2 U.S. mobile carriers plan a smart-phone-based, contactless payment system that would compete with credit and debit cards from Visa (NYSE:V - News) and MasterCard (NYSE:MA - News), Bloomberg reported, citing sources. AT&T (NYSE:T - News) and Verizon Wireless, a Verizon (NYSE:VZ - News) -Vodafone (NMS:VOD) venture, are reportedly teaming up with Deutsche Telekom's T-Mobile USA, Discover Fin'l (NYSE:DFS - News) and Barclays (NYSE:BCS - News) to test a system in Atlanta and 3 other U.S. cities. MasterCard shares fell 3.7% and Visa 1.5%. AT&T and Verizon rose.