Advanced Mobile Phone Service: Mobile Telephone Switching Office

The Advanced Mobile Phone Service (AMPS) provides high-capacity, high-quality mobile telephone service to a large number and variety of customers. The system blends two major communication disciplines: radio transmission and switching. The radio subsystem is based on cellular FM technology1,2 operating in the 850-MHz band. The switching subsystem is implemented on the No. 1/1A family of the Electronic Switching Systems (ESS). As described in Ref. 3, the central coordinating element for AMPS is the Mobile Telephone Switching Office (MTSO). It controls the AMPS system and interfaces it with the land telephone network. The MTSO provides mobile customers with services that are similar to those available for land telephones. Basic mobile service includes direct dialed mobile-to-mobile, mobile-to-land, and land-to-mobile calling. An MTSO serves a large geographic coverage area, and all AMPS mobile calls are switched through it. The AMPS radio equipment is located in remote cell sites.2 Each cell site also contains duplicated stored program controllers, data link interface equipment, and auxiliary maintenance equipment. Cell sites 71