Call state processor for a time division switching system

摘要

A semiautonomous digit collection and call state detection subsystem is provided for use in a time division switching system such as a PBX. Each active (call serving) system port circuit applies a hook state signal to a specially provided bus during each occurrence of the time slot to which the port circuit is assigned. The subsystem's logic analyzes these hook state signals to identify certain predetermined call states and to count dial pulses. Output messages representing identified call states and dialed digits are made available to the switching system under control of a system scanner.