随着交换网络的发展,NGN逐步成为交换网发展的必然方向,但PSTN仍然是当前的立身之本,传统话音依然是目前电信运营商最主要的业务收入来源,而且向NGN过度也将是一个较长的过程。文中首先介绍了PSTN网的特点及面临的问题,然后描述了传统PSTN网向基于分组交换的NGN网演进的目标和方案,最后对NGN网络也进行了深入的分析,并阐述了从PSTN网络智能化改造向NGN的演进的过程。 With the development of switching networks, NGN has gradually become the inevitable direction for the development of switching networks. However, PSTN is still the current foundation for its development. Traditional voice is still the most important source of business revenue for telecom operators at present and it will also be one Longer process. This paper first introduces the characteristics and problems of PSTN network, and then describes the goal and scheme of traditional PSTN network evolving towards NGN based on packet switching. Finally, it also analyzes NGN network in-depth, and elaborates from the PSTN network intelligence Transformation of NGN to the process of evolution.