摘要： 从如何提高基于SIP 协议的VoIP 系统的语音质量出发，分析了该系统与MPLS 技术结合处的难点，并提出了一种支持QoS 的SIP代理服务器模型的解决方案。该方案的设计结构清晰、可扩展性强，解决了SIP 代理服务器在IP 网络中没有会话服务质量控制能力的问题，是一种好的融合VoIP 及MPLS 两大技术的应用模型。该方案目前已运用于基于嵌入式Linux 平台的VoIP 系统中，完全能够满足高质量语音的需求。

关键词: SIP 代理服务器；SIP；服务质量；VoIP；MPLS

Abstract: This paper depicts how to improve the voice quality of VoIP system based on SIP protocol, and then analyses the difficulty in combining this VoIP system with MPLS technology. And it presents a design model and implementation of SIP proxy server for QoS required network. This model has good expansibility and a clear framework, and gives a solution to the problem that SIP Proxy server without any QoS abilities. It is a nice application-model merges MPLS technology into VoIP system. This solution is already adopted in the VoIP system under embedded Linux platform and it meets the requirement of high quality of voice communication well.

Key words: SIP proxy server; SIP; QoS; VoIP; MPLS