OPTICAL FIBER SIGNAL TRANSMISSION MACHINE; OPTICAL FIBER SIGNAL REGENERATOR; OPTICAL FIBER SIGNAL RECEIVER; OPTICAL FIBER COMMUNICATION MACHINE, NAMELY, SYNCHRONOUS DIGITAL HIERARCHY ADD-DROP MULTIPLEXER, FIBER OPTICAL MODEM AND OPTICAL REPEATER; COAXIAL CABLE SIGNAL CARRIER; SIGNAL RECEIVER; PULSE CODE MODULATION SIGNAL CARRIER, NAMELY, T1/E1 LEASE LINE EQUIPMENT, SUCH AS MODELS AND MULTIPLEXERS; SIGNAL INTENSIFIER; SOUND AMPLIFIER; RADIO TRANSMITTER; ELECTRONIC SWITCH; TELECOMMUNICATION MAC...