the method for measuring the QoS for VoIP network is introduced and the main elements affecting VoIP QoS performance such as delay jitter
packet loss and IP network delay analyzed.The relationship between its end-to-end voice quality and delay is quantitatively analyzed by using the E-model
the main delay components in the VoIP system pointed out by setting up a mathematical model and the mechanism of their generation and parameters affecting them studied.In the design of a practical VoIP system
it is possible to improve its delay by optimizing these main parameters.