Line connection method for telecommunications exchanges - esp telephone exchanges systematically avoiding unsuitable connections

摘要

Any connection through an exchange is defined by its source and/or destination and the exchange network plane which is divided into several categories. A first selector in the exchange has an input and an output for its own category with regard to the network hierarchy. A second selector has an input for each destination defined by a routing digit and an output for a selection series for connections to the required destination such that one line group may be selected which has at least one clear line. The first selector is hardwired and the information is specific for all exchanges and does not need to be changed for addition or removal of line groups. The second is a storage unit which may have its contents altered without changing its construction. This has the advantage that changes in the network such as line group additions or removals are easy to incorporate.