ELECTRICAL APPARATUS FOR TRANSMITTING AND RECEIVING DATA, NAMELY, SWITCHES, TELEPHONE, DATA, SIGNAL AND INFORMATION EXCHANGES, MULTIPLEXERS, OPTICAL MULTIPLEXERS, CONNECTORS, DIGITAL CROSS CONNECTORS, ASYNCHRONOUS TRANSFER MODE SWITCHES, PRIVATE BRANCH EXCHANGES, CONVERTERS, MODEMS, RELAYS, REPEATERS, AMPLIFIERS, LIMITERS, ROUTERS, TRANSMITTERS, RECEIVERS, ANTENNAS, CABLES, TELEPHONES