Circuit Switched Core Network (CS-CN) http://proneer.tistory.com/trackback/327http://proneer.tistory.com/entry/%ED%9A%8C%EC%84%A0-%EB%A9%94%EC%8B%9C%EC%A7%80-%ED%8C%A8%ED%82%B7-%EA%B5%90%ED%99%98%EB%B0%A9%EC%8B%9DCircuit-Message-Packet-switching회선, 메시지, 패킷 교환방식