The usage of frequencies within the United States is regulated by the Federal Communications Commission (FCC). Some frequency bands may be vulnerable to interference by existing services in adjacent frequency bands, such as UHF television broadcasting. In addition to radio frequencies used to connect handsets with cellular base stations, other parts of the radio spectrum are used to interconnect base stations and the wired telephone network. Different cellular companies in the same region may use different levels of cellular technology and different parts of the radio spectrum. Companies wishing to provide cellular services in a geographic region compete for the right to license radio spectrum in spectrum auctions. As cellular mobile telephone technology has evolved over time, periodically bands of frequencies are reassigned from other radio services. Cellular frequencies in the United States are allocated by the US Federal Communications Commission.
