软交换讲义，包括软交换的基本原理，体系结构，媒体网关技术，信令网关技术，接入网关技术，呼叫控制，软交换协议等内容。-soft exchange notes, including soft exchanged the basic principles, architecture, media gateways, signaling gateways, access gateways, call control, soft-exchange agreement content.