The world's largest retailer wants a chunk of the wireless-carrier game. So on Sunday, Wal-Mart (NYSE:WMT) is introducing low-end cell-phone service nationwide.

Powered through America Movil's (AMEX:AMX) TracFone Wireless, the prepaid plans start at $30 a month and max out at an industry-awakening $45 a month for unlimited minutes, text messages, and data.

This is naturally going to be a shot to the gut of giants AT&T (NYSE:T), Sprint Nextel (NYSE:S), and Verizon Wireless, who all wield costly usage plans and anchor customers to two-year commitments. However, at least the big boys have exclusivity deals with the hottest smartphone models. Since Wal-Mart's Smart Talk service is not tied to a long-term contract, it's not going to subsidize the fancy smartphones. It's offering three entry-level handsets, and customers have to pay the full $40 to $100 price.

The players quivering now are the cheaper providers. Wal-Mart's gunning for MetroPCS (NYSE:PCS), Leap Wireless' (NASDAQ:LEAP) Cricket, and Virgin Mobile (NYSE:VM).

Don't start digging any graves, though. Wal-Mart doesn't always get what it wants: Its forays into DVD rentals, social networking, and digital downloads have been embarrassing flops.

Wireless service may be another fiasco, but I wouldn't bet against Wal-Mart. The discounter attracts the perfect audience to pitch low-end yet full-featured prepaid wireless service. Its presence will keep industry prices in check, and that's where shareholders in all of the wireless carriers need to worry.

Sprint Nextel and Wal-Mart Stores are Motley Fool Inside Value selections. America Movil is a Motley Fool Global Gains recommendation. Try any of our Foolish newsletter services free for 30 days. Now that's window shopping!

Longtime Fool contributor Rick Munarriz wonders whether you can buy Straight Talk through an express lane. He owns no shares in any of the companies in this story and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.