The FCC divides the United States into 306 Metropolitan Service Areas (MSA) and 428 Rural Service Areas (RSA) and assigns every county to one of these markets. The MSA/RSAInfo map database provides both geographic and demographic information on the cellular providers licensed to offer service in these markets.

Within each cellular market, multiple companies are licensed to provide cellular service. These companies are commonly referred to as the 'A side' and 'B side' providers - depending on the frequencies they use. Some rural markets have more than two companies providing cellular service, these markets are called 'B side splits'.