Trunking and traffic principles of a p.c.m. telephone exchange

A description is given of a method of trunking a telephone exchange situated within a p.c.m. transmission network. It is assumed that all external connections are p.c.m. junctions, either to other exchanges or to concentrators, and that switching is to be achieved without decoding. The exchange is required to switch the contents of a channel in an incoming pair to a free channel in a selected outgoing pair, and, in general, storage of the information is required so that a change in time slot can be achieved. Methods of obtaining access to the storage elements and techniques which facilitate economic provision of the storage are discussed.