Abstract: A composite network protective/recovering device includes first to fourth input/output (I/O) modules. The first and third I/O modules are operational modules and the second and fourth I/O modules are protective modules. A first span connection group connects the first I/O operational module with the second I/O protective module. A second span connection group connects the third I/O operational module with the fourth I/O protective module to perform span switching. A first bidirectional line switching ring connects the first I/O operational module and the third I/O operational module to form a bidirectional ring which has two lines in each direction. A second bidirectional line switching ring is connected to the first to fourth I/O modules to form transmitting/receiving operational lines which include two lines in each direction and protective lines which include two lines in each direction.

Abstract: A telephone network with distributed processing capabilities. A local controller is provided for monitoring status of a plurality of users. A primary controller performs circular polls of the local controllers to determine status changes. The system operates in a time division multiplexed fashion, and the primary controller assigns during which time slot each particular conversation will occur. A synchronizer for synchronizing between the primary and the secondary controller is also provided. In addition, the ring timing for the subscriber premise can be performed in the microprocessor at the subscriber premise.