AT&T, Verizon, Sprint and U.S. Cellular represent four of the biggest wireless service providers active in 2011. All four companies provide a wide range of services and mobile phones. AT&T is a GSM provider, so their phones all require SIM cards. Verizon, Sprint and U.S. Cellular all use CDMA technology, so their phones don’t take SIM cards. Each company has its own advantages to consider when choosing a provider. Writer Bio
