The MME 100 performs management and control of mobility of the UE 60. The MME 100 is connected to the eNB 70. The MME 100 relays control data between a node device in the core network, and the eNB 70. Alternatively, the MME 100 transmits control data generated in the local device to the eNB 70 or the node device in the core network. Control data may be referred to as control (C)—plane data. Moreover, it is known that data used for an IoT service transferred between the UE 60 and the AS 130 has a small capacity and data size, as compared with general user data. Thus, data used for an IoT service may be transferred as control data between the AS 130 and the UE 60 via the SCEF 110, the MME 100, and the eNB 70. Data used for an IoT service may be referred to as, for example, small data. The MME 100 may execute traffic control on small data transmitted as control data from the UE 60. The MME 100 receives, via the SCEF 110, information relating to a transmittable data amount determined in an application server 30. Then, the MME 100 executes traffic control on the data transmitted from the UE 60, by using information relating to a transmittable data amount.

The SCEF 110 executes authentication or the like relating to the AS 130 disposed on the external network. Further, the SCEF 110 transmits, to the AS 130, a parameter relating to the UE 60. The parameter relating to the UE 60 may be, for example, a parameter required for the AS 130 to provide a service to the UE 60. The SCEF 110 is equivalent to a service control device 20 in FIG. 1. The SCEF 110 is disposed between the MME 100 and the AS 130.