ARRANGEMENT FOR HANDLING PERMANENT SIGNALS

摘要

A multistage switching network is disclosed with lines terminated on the first stage, conventional permanent signal trunks terminated on the last stage and overflow permanent signal trunks terminated on links which interconnect the first and last stages. In response to a permanent signal condition on a line, common control apparatus tests the line to ascertain whether the permanent signal was caused by a trouble condition or a receiver off-hook. Based on this test the line is connected to the appropriate trunk.