Wal-Mart Stores Inc. (NYSE: WMT) hopes to expand its Straight Talk prepaid wireless service to include phones which will operate on AT&T’s (NYSE: T) GSM wireless network.

The discount retailer’s “Straight Talk” service was previously only available on phones on Verizon Wireless’s (NYSE: VZW) CDMA wireless network. Straight Talk is operated by TracFone Wireless, a company which also sells prepaid cell phone services. TracFone is a unit of Mexican telecom company America Movil.

Prepaid cell phone options have been increasingly popular as consumers have become less willing to sign two-year contracts and have instead opted for prepaid or month to month services, which are often more cost effective and do not require contracts.

The addition of AT&T phones to Wal-Mart’s Straight Talk service was first reported by Walter Piecyck, an analyst at BTIG Research, and the Wall Street Journal.

Bloomberg reported that AT&T confirmed the expansion but was not able to reach a Wal-Mart Stores Inc. (NYSE: WMT) spokesperson for a comment.

Wal-Mart Stores, Inc. (Walmart) operates retail stores. The Company operates in three business segments: Walmart U.S., International and Sam’s Club. During the fiscal year ended January 31, 2010 (fiscal 2010), The Walmart U.S. segment accounted for 63.8% of its net sales, and operated retail stores in different formats in the United States, as well as Walmart’s online retail operations, walmart.com. The International segment consists of retail operations in 14 countries and Puerto Rico. During fiscal 2010, the segment generated 24.7% of the Company’s net sales. The International segment includes different formats of retail stores and restaurants, including discount stores, supercenters and Sam’s Clubs that operate outside the United States. The Sam’s Club segment consists of membership warehouse clubs in the United States and the segment’s online retail operations, samsclub.com. During fiscal 2010, Sam’s Club accounted for 11.5% of its net sales.

Shares of Wal-Mart Stores Inc. (NYSE: WMT) traded up 0.25% on Friday ending the week at $51.19.

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