Electronic key telephone systems

Communication apparatus including telephone systems including electronic key telephone system, electronic key telephone handsets, switching system, PABX system; computer hardware and software including communication hardware and software; acoustic conduits, audiovisual teaching apparatus, cabinets for loudspeakers, cash registers, computers, control panels for electricity, distribution boards for electricity, distribution boxes for electricity, distribution consoles for electricity, electric connections, electric contacts, electric discharge tubes other than for lighting, electric measuring devices, electric monitoring apparatus, electric regulating apparatus, electric relays, electric resistances, electric switches, electricity conduits, electricity ducts, electricity switchboxes, electricity terminals, electricity transformers, electricity wire connectors, electromagnetic coils, galvanic batteries, galvanic cells, glass covered with an electrical conductor, integrated circuits, identification sheaths for electric wires, identification threads for electric wires, intercommunication apparatus, lasers (not for medical purposes), loudspeakers, magnetic wires, magnets, masts for wireless aerials, measuring instruments, optical apparatus and instruments, optic mirrors, optical fibres, optical lenses, oscillographs, photometers, phototelegraphy apparatus, plugs, printed circuits, radios, vacuum tubes, receivers, semi-conductors, signal filters, signalling panels, sockets and other contacts for electric connections, sound recording apparatus, sound reproduction apparatus, switchboards, telecommunication transmitters, telegraph apparatus, telegraph wires, telephone apparatus, telephone receivers, telephone or telegraphic transmitters, telephone transmitters, telephone wires, teleprinters, teletypwriters, television apparatus, thermionic lamps and tubes, thermionic valves, transmitters for electronic signals, transmitters of electronic signals, vehicle radios, wafers (silicon slices)