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1 VoIP 简介1.1 VoIP 主要应用协议随着用户规模的扩大以及用户对业务需求的增长,网关在规模上要不断扩大。集中型的网关结构在可扩展性、安全性以及组网的灵活性方面的不足日益显露出来。因此,将业务、控制和信令分离的概念被提了出来,即将IP 电话网关分离成三部分:信令
1 Introduction to VoIP 1.1 Major VoIP Application Protocols With the expansion of users and the increase of users’ demands for services, the gateways must be expanded in size. The lack of scalability, security, and networking flexibility of a centralized gateway fabric is increasingly apparent. Therefore, the concept of separation of business, control and signaling was introduced by separating the IP telephony gateway into three parts: signaling