CLOCKING ARRANGEMENT

A line switch for a digital telephone switching system utilizes distributed processing. The line switch comprises one or more switch modules. Each switch module is coupled to a central office switching system via one or more PCM lines which utilize common channel signaling. Each switch module comprises groups of line circuits, each line circuit being coupled to a subscriber line. Three separate distributed processor functions are provided in each line switch module. A first processor is utilized to communicate with the central office switching system and to coordinate the operations within the line switch module. A second processor is provided to control clock generation and rate conversion circuits. Each group of line circuits includes a third processor to control the operations of the line circuits and to gather information from the line circuit. The second processor is used to select which of a plurality of sources may be used to provide clock signals within the line switch module.