PURPOSE: To ensure an effective telephone connection in the stored program exchange system, by connecting the backup position equipment directly to the information desk in case some fault arises within the equipment and then controlling the incoming circuit or using the service talkie.
CONSTITUTION: Incoming trunk ICT is started by the start sent from the incoming circuit, and trunk ICT is scanned by trunk scanner TSCN. Then vacant position equipment POS is selected by the program control, and thus switch controller SC and relay controller RC are controlled to connect the incoming circuit to equipment POS. And now if some fault occurs to TSCN, SC, RC, CPU and other units to be detected by fault detection controller TRC, backup position equipment BUPOS is connected directly to information desk ATT in respone to the dial-tone of the incoming circuit. Here the incoming lines are generally more in number than the units at the outgoing side. In this connection, the incoming circuit is closed to prevent the incoming of the call or the call is treated by the service talkie. In this way, an effective telephone connection is possible in the stored program exchange system.
ISHIBASHI YOSHIJI
ONO TAKAO
KAWAKATSU HIDEO
NIPPON TELEGRAPH & TELEPHONE
FUJITSU LTD