National: AT&T, Sprint, T-Mobile and Verizon are the national carriers, often called the Big Four. They have the most customers and maintain the networks that tier-two carriers and resellers use.
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Mobile virtual network operators (MVNOs) in the United States lease wireless telephone and data service from the three major cellular carriers in the country, AT&T Mobility, T-Mobile US, and Verizon , as well as the regional carriers such as UScellular, for resale.
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