A switching system which includes subscriber's circuit device connected to terminals and a subscriber's circuit controlling apparatus between a host apparatus and subscriber's circuit devices for controlling the subscriber's circuit devices in accordance with a control order corresponding to control information from the host apparatus. Each of the subscriber's circuit controlling apparatuses includes an order processing unit which analyzes control information which is transmitted from the host apparatus for comparing the received control information with last received control information and transmits a control order to the subscriber's circuit devices. The order processing unit transmits control orders a number of times to the subscriber's circuit devices and accepts a fault report, from the subscriber's circuit devices to retransmit a control order. The subscriber's circuit devices receive the control order a number of times for collating the control orders and outputs a fault report when in disagreement.