Abstract: In an IN where the same service is provided by a plurality of SCPs, data consistency is maintained when an update occurs to subscriber data as a result of processing a service for a subscriber. When an update is made to a subscriber database in an SCP, update information is sent to the other SCPs by way of a route selected from among a route via a common channel signaling network, a route via a LAN, and a route via an SMS. Updates occurring during backup or restore processing on a main subscriber database in the SMS are accumulated within the SMS, and the accumulated updates are applied to the main subscriber database after completion of the processing.