Abstract: A digital switching device of the stored program type operating under the control of a central control unit has a first stage which multiplexes digital signals from a plurality of line units and separates data signals from signalling information. The data signals are fed to an input time switching stage. The input time switching stage operates under the control of the central control unit to transmit signals from an input port in a particular time slot on a highway to an output time switching stage. The output time switching stage transmits the data signals to the first stage which combines them with signalling information and after demultiplexing transmits them to appropriate ports.

Abstract: A digital switching device of the stored program type operating under the control of a central control unit has an input time switching stage, an output time switching stage, and a space switching stage intermediate the time switching stages. Each time switching stage has a connection store for controlling reading of data from said stages, and the space switching stage includes comparators for comparing the contents of the connection stores. The space switch is controlled on the basis of the comparison.

Abstract: A digital switching device of the stored program type operating under the control of a central control unit has a multiplexing stage for multiplexing signals from a plurality of ports, an input time switching stage which receives multiplexed signals from the multiplexing stage and outputs them in appropriate time slots, an interface unit connecting the input time switching stage to an output time switching stage and a demultiplexing stage which demultiplexes signals from the output time switching stage for transmission to said ports. The interface unit is an interchangeable unit which either provides a direct connection between the input and output time switching stages or comprises a space switching stage.