* Cellular telephony provides communication between two devices. One or both may be mobile. * A cellular service area is divided into cells. * Advanced Mobile Phone System (AMPS) is a first-generation cellular phone system. * Digital AMPS (D-AMPS) is a second-generation cellular phone system that is a digital version of AMPS. * Global System for Mobile Communication (GSM) is a second-generation cellular phone system used in Europe. * Interim Standard 95 (IS-95) is a second-generation cellular phone system based on CDMA and DSSS. * The third-generation cellualr phone system will provide universal personal communication. * A satellite network uses satellites to provide communication between any points on earth. * A geosynchronous Earth orbit (GEO) is at the equatorial plane and revolves in phase with the earth. * Global Positioning System (GPS) satellites are medium-Earth-orbit (MEO) satellites that provide time and location information for vehicles and ships. * Iridium satellites are low-Earth-orbit (LEO) satellites that provide direct universal voice and data communications for handheld terminals. * Teledesic satellites are low-Earth-orbit satellites that will provide universal broadband Internet access.