According to the theory of multimedia synchronization and present, some key parameters and mathematical relationship of QoSs, such as maximum number of buffers, and minimum number of pre storage voice packets, are analyzed.

• 并借鉴多媒体同步与表现的有关理论 ；建立了 IP电话网关中缓冲区设置数目和预取语音包数目的计算模型 .