Fuente: Wipo "digitalization" ABSTRACT A telephone switching system for telephone trunk and subscriber lines that carry voice and associated supervisory information signals. The voice signals are received through one of a plurality of ports under the control of a port event pro- cessor, and are transferred through a switching arrangement under the control of a call processor for transmission through a second port. The supervisory information is also received as sense supervisory information with the associated voice signals, and is sampled and stored in a port data store memory. The call processor can retrieve or modify the supervisory information stored in the port data memory store, and can store control information in the port data store. The port event processor enables the transfer of certain supervisory information as control supervisory information from the port data store for transmission with the associated voice signals through the respective port. The port event processor also performs certain operations specified by the commands and supervisory information stored in the port data store memory. The port event processor and port data store memory both operate under control of timing signals from a timing signal generator. The timing signal generator generates timing signals of two frequencies. The port data store memory samples the sense supervisory information signals at a rate dependent upon the higher frequency timing signal, and the port event processor controls the operation of the respective ports in response to the lower frequency timing signal.