The Research Of Technology Of Examination And Limitation To VoIP And Application In Yangzhou Telecommunication Company

With the VoIP technology developing, lots of new VoIP applications strongly attracted users by lowest price but at the same time brought huge impact to the traditional PSTN voice services. Because of the simplicity and flexibility of VoIP deployment, many secret organizations want to provide the illegal VoIP services supported by the network resources owned by legal telecommunication companies. These behaviors, not premised by TSCC(Telecommunication Service Classified Catalogue), have many serious disadvantages, such as violating the country policy of supervising and managing the VoIP services, seriously disturbing the normal order of telecommunication market, diverging the massive businesses of long-distance telephone, and the inestimable economic loss for the traditional telecommunication operation business ,even threatening country information and society security. Therefore, it is emergent to increase efforts in monitoring on illegal VoIP services. Besides continuing carrying on the essential standard and the purification to the VoIP market using the legal instrument, the most important task is studying and discussing how to use advanced technical methods to inspect and attack the illegal VoIP service.Under this background, Yangzhou telecommunication established a project on the Illegal VoIP examination and limit system. Through the dissection to the VoIP technology realization principle, it analyzed and discussed the VoIP examination and limitation mechanism, and finally formed a systematic solution.Firstly this article carries on the comprehensive introduction to VoIP and the VoIP agreement technology, and analyzes the process of realization of VoIP signaling flows and the media flows, also analyzes the process of the call setup as well as the media transmission. Secondly it analyzes and studied three main mechanisms of examination and blocking and disturbing the VoIP packages, then summarizes the realization process of illegal VoIP recognizing and limiting system. Finally discusses the system deployment and application, and produces system deployment plan of the Yangzhou telecommunication city territory net exportation.This paper does some research on the practice content and at the same time it is the experiment site project of Jiangsu Province Telecommunication Company.