The Federal Communications Commission regulates wireless telephone companies. The agency provides these and other terms at its Web site, fcc.gov/cib/handbook.

Analog signal: A signaling method that uses continuous changes in the amplitude or frequency of a radio transmission to convey information. An analog mechanism represents data by measurement to a continuous physical variable such as voltage or pressure.

Bandwidth: The capacity of a telecom line to carry signals. The necessary bandwidth is the amount of spectrum to transmit the signal without distortion or loss of information. FCC rules require suppression of the signal outside the band to prevent interference.

Boadband: A descriptive term for evolving digital technologies that provide the consumer a signal switched facility offering integrated access to voice, high-speed data service, video-demand services and interactive delivery services.

Cellular technology: Often used for all wireless phones regardless of the technology they use; derived from the cellular base stations that receive and transmit calls. Both cellular and PCS (Personal Communications Service) phones use cellular technology.

Digital: Data transferred in the form of numerical digits.

E-mail: Electronic mail, referring to messages sent over the Internet but now also being sent and received by newer types of wireless phones.

Global Positioning System (GPS): A U.S. satellite system that lets those on the ground, on water or in the air determine their position with extreme accuracy using GPS receivers.

Personal Communications Service: Any of several types of wireless, voice, and/or data communications systems, typically incorporating digital technology; PCS licenses most often used to provide services similar to advanced cellular mobile services and other wireless communications services.

Roaming: The use of a wireless phone outside of the home area defined by a provider; higher per-minute rates usually charged for calls made or received by roaming.

Spectrum: The range of electromagnetic radio frequencies used in the transmission of sound, data and television.