Abstract: Apparatus is described for testing a telephone line between a customer's telephone and a local exchange associated therewith. The apparatus comprises a field unit positioned between the customer's telephone and the line, an exchange unit positioned at the exchange, and a microcomputer associated with the field unit for controlling operation of the field unit and the exchange unit. The field unit and the exchange unit each have means for transmitting frequency tones down the line and means for measuring the voltage across the line. The microcomputer is programmed to calculate the loudness rating of the line from the measured voltage values.

Abstract: A communication system able to provide multiple path communication between a plurality of stations operating on a single channel. The stations are synchronized and a cyclically repeating series of time slots is defined. One time slot in each cycle is reserved for the transmission of synchronization information by a station designated the master station for reception by the other stations, designated slave stations, and maintaining synchronization therein. Another time slot is reserved for any slave station to transmit a message that it requires to communicate to another station, such indication preferably being by transmitting its own pre-assigned address code. The remaining time slots are used for transmitting address information and data. The slave stations operate in a low power condition except during one of the other time slots when they may receive their own address, or except when they need to transmit data.