Abstract: A redundant data transmission and storage system in which a plurality of transmission circuits are connected in series to form a channel network. Each transmission circuit includes at least two redundant data channels which are each capable of independent operation. For each transmission circuit, the selection of which channel, if any, is enabled in the active state is made by a channel control unit associated with that particular transmission circuit.

Abstract: A local message metering system for metering each subscriber's use of a telephone system. Scanner banks periodically address the subscriber circuits to store data about subscriber usage in scanner bank adapters. One or more remote tributary offices are connected to a recording office over data links which connect to the scanner bank adapters. Single channel and redundant, two-channel data links are employed. Redundant channels are controlled by interlocked control networks. The data links are controlled by data transmitters and data receivers. The data receivers are addressed along with the scanner bank adapters to transfer data over data paths to external storage units. Redundant data paths are controlled by interlocked control networks. The redundant data links operate independently of the redundant data paths.