Electronic equipment, installations and systems for communications engineering and telecommunications, namely, devices for digital and analog telephone exchange and transmission installations, namely, gateways, routers, least-cost routers and switches for wireline and wireless networks, route-diversity systems comprised of computer hardware, routers and switches, backup-dial tone systems comprised of computer hardware, routers and switches, business continuity systems comprised of computer hardware, routers and switches, messaging systems comprised of computer hardware and software for storing voice and data messages digitally, wireless local-loop systems comprised of computer hardware and telecommunications software for transmitting wireless digital messages, mobile office systems comprised of computer hardware, data transceivers, routers and switches; messaging, alarm and notification systems comprised of data transceivers, wireless networks, and gateways for collection and management of data, alarm central units, switches and routers, computer hardware and telecommunications software for operating the messaging, alarm and notification systems; accessories for measuring and testing equipment, namely, electronic interface circuits, matching electrical connectors, test adapters, flexible electric cords for measuring and testing equipment; gateway routers in the nature of computer control hardware; mobile computing and operating platforms consisting of data transceivers, wireless networks, and gateways for collection and management of data, switches and routers; change-over switches for telecommunication apparatus; telecommunication switches; devices, namely computer hardware and telecommunications software for transmitting wireless digital messages, signals, data, facsimiles, images and information, wireless facsimiles; wireless facsimile machines