Distributed control digital switching system (The ITT/Alcatel System 12) U.S. Patent 4,201,889
A distributed control digital switching system is described in which a plurality of subscriber lines and trunks are provided with a switched access to various processing functions shared over a plurality of time shared multiplexed lines. Each processor of a first group of processors is dedicated to a group of terminals such as subscriber lines or trunks, and communicate with processors in a second group to provide pooled processing functions to one or more of said groups of terminals through a digital switching matrix. Processors in the first group perform a first set of processing functions, such as path set up and processors of the second group perform a second set of processing functions, such as call control. A multistage switching network provides a modularly expandable digital group switch, the operation of which is controlled externally from the terminals to which it is connected, and provides rate synchronous, phase (bit) asynchronous interconnection among the terminals which are interfaced and switched. Each processor of the first group is time shared over a security block of lines or trunks providing hardware interface therebetween while each processor of the second group provides pooled functions for a plurality of security blocks of lines and trunks. All data, speech and control signals are coupled over common transmission paths.
Lawrence, Alan J.; Cotton, John M.; Hamer-Hodges, Kenneth J.; and Denenberg, Jeffrey N., "Distributed control digital switching system (The ITT/Alcatel System 12) U.S. Patent 4,201,889" (1980). Engineering Faculty Publications. 95.
Lawrence; Alan J. , Cotton; John M., Hamer-Hodges; Kenneth J. , Denenberg; Jeffrey N. , Distributed control digital switching system (The ITT/Alcatel System 12) U.S. Patent 4,201,889 issued May, 1980