Wal-Mart Stores (NYSE: WMT) announced its own postpaid wireless brand, the strongest indication yet that the mammoth retailer hopes to cash in on mobile.

The service, called Wal-Mart Family Mobile, will run on T-Mobile USA's network and will cost $45 per month for unlimited voice and texting; additional lines can be added for $25 per month. Interestingly, there is also a prepaid component to the plan: Users who want mobile data can pay into a prepaid account that can be pooled for an entire family. According to the AP, 1 GB of data usage will cost $40.

Importantly, Wal-Mart's plan does not have a contract for customers to sign or come with early-termination fees. However, phones for the offering will be locked to Wal-Mart's service and will not be able to work on other networks or even under a T-Mobile plan.

Beginning Monday, Wal-Mart will start selling the service with five phones, including the Android-powered Motorola (NYSE: MOT) Cliq XT, a T-Mobile exclusive, for $249. T-Mobile sells the Cliq for $329 to customers who do not sign a contract and sells it for free to customers who sign a two-year contract. Wal-Mart also will sell cheaper phones with the service, including a basic Nokia (NYSE: NOK) phone for $35. 

Wal-Mart is working to distinguish this new service from other wireless plans it has been offering. Since 2009, Wal-Mart has been selling TracFone's Straight Talk service. Straight Talk, a prepaid unlimited service, offers users unlimited talk, texting and mobile Web access for $45 per month. Verizon (NYSE: VZ) Wireless initially provided connectivity for the service, but earlier this summer, Wal-Mart began selling phones for Straight Talk that run on AT&T (NYSE: T) Mobility and T-Mobile's networks. Wal-Mart also has been selling Sprint Nextel's (NYSE: S) pay-per-minute prepaid service, Common Cents Mobile.

Greg Hall, vice president of merchandising at Wal-Mart U.S., told the AP that by providing a postpaid service Wal-Mart hopes to overcome the perception that prepaid services do not offer the best phones, including smartphones. (Straight Talk does not offer smartphones.)

"What we saw was an opening in the marketplace for really bringing family savings and a family plan and T-Mobile was a great partner there," Hall told the AP.

This article originally published here. Get your wireless industry briefing here.

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