An SCP is provided with a pattern notifying unit. The pattern notifying unit is configured so that, on the occasion of providing a service utilizing ISUP interwork between a first leg defined between an originating switching center and a forwarding MSC and a second leg defined between forwarding MSC and a receiving MSC, it notifies the forwarding MSC of an interwork pattern number corresponding to a category of the service. The forwarding MSC according to the present invention performs processes such as "abandon and then generate" and "transmit" to parameters with reference to an interwork pattern corresponding to the interwork pattern number provided.