CORE NETWORK AND COMMUNICATION SYSTEM

摘要

A core network that is connected to a mobile communication network and a network, and that establishes voice communications between communication devices, receives, from the mobile communication device, an incoming notification response that indicates at least one codec that can be used on an incoming mobile communication device. The core network specifies, as a codec that should be used by the incoming mobile communication device, a shared codec from among originating codec and at least one codec that can be used by the incoming mobile communication device indicated in the incoming notification response, or a codec having the closest transmission rate to the transmission rate of the originating codec that can be used on the core network and the incoming mobile communication device.