Disclosed is a technique for enabling a device that needs to send high priority and high bandwidth user plane traffic to send the user plane traffic even in the case where a group bandwidth has an upper limit in group-based communication. According to the technique, when an MTC device that is to send high priority and high bandwidth user plane traffic sends a service request to a network node (P-GW 213a), the network node allows use of a minimum bandwidth bearer in the case where the upper limit of the group bandwidth is exceeded. The MTC device sends a traffic sending request to an MTC server 214a via the bearer. The MTC server stops traffic of an appropriate other MTC device, to secure a bandwidth for the MTC device having the high priority and high bandwidth user plane traffic.