Electronic step-by-step telephone switching system

Abstract

An electronic step-by-step switching system utilizes much of the equipment now present in conventional electromechanical step-by-step telephone exchange switches. Conventional line finders, selectors and connectors are modified by removing the relay logic and replacing it with microprocessor based controllers. The modified line finders communicate through a bus with an originating controller and the modified connectors communicate through a bus to a terminating controller. The controllers are interconnected for data exchange through high speed buses that are supervised by a bus controller. A programmer station is installed for bi-directional communication through the bus controller. The originating and terminating controllers include memory storage for maintaining status information concerning the subscriber lines within the groups of corresponding line finders and connectors. The modified line finder works in conjunction with the originating controller to identify the line for an off-hook subscriber. The line number is translated to a telephone number by the originating controller making possible the addition of functions and revenue features for a local telephone exchange. Likewise, the addition of identifying information about called parties by the storage of information in the terminating controller makes possible the addition of still further features which can be implemented in a substantially conventional electromechanical step-by-step telephone exchange.