Returning to FIG. 3, the SCEF 110 authenticates the set chargeable party request message, in order to ensure application traffic relating to the AS 130 (S13). Next, the SCEF 110 sets the parameter determined in step S11 in an update CP parameter request message as a CP parameter, and transmits the CP parameter to the MME 100 (S14). Herein, the MME 100 may hold the CP parameter set in the update CP parameter request message. Thereafter, the MME 100 transmits an update CP parameter response message to the SCEF 110 (S15). Next, the SCEF 110 transmits a set chargeable party response message to the AS 130 (S16). Note that the AS 130 may set the CP parameter determined in step S11 to a message differing from the set chargeable party request message, and then transmit the message to the SCEF 110. The SCEF 110 may set the CP parameter to a message differing from the update CP parameter request message, and then transmit the message to the MME 100. For example, a T 8 set suggested network configuration request message may be used instead of the set chargeable party request message. A set suggested network configuration request message may be used instead of the update CP parameter request message. Moreover, a set suggested network configuration response message may be used instead of the update CP parameter response message. A T 8 set suggested network configuration response message may be used instead of the set chargeable party response message.