The Research And Application Of VoIP Communication System Based On Soft-switch

Almost all of companies have access to data networks, and launched various operations on the network such as office system. How to make their own data networks brings greater efficiency for companies is a real question that the enterprises should consider, on the one hand considering improving production efficiency through data networks, on the another hand considering the cost savings. One common practice is running through the existing data network. The concrete realization is increasing IP PBX server on the original network, and achieving voice communications by setting up an additional IP phone or VoIP gateways in headquarters and various branches of the network structure. It can also provide traditional voice interface, and enterprises existing telephone switches (PBX), and long-distance calls to bypass IP network, thereby saving the user's long-distance calls, while providing rich value-added services for enterprises.IP PBX is the PBX over IP, its ultimate purpose is to replace the existing PBX. The structure of the existing PBX is not open enough and the value-added business provides is poor, but for the IP-based PBX, its opening up capacity and ability to expand are significantly enhanced. If the integration of the IP PBX and the NGN can be success, it will create a lot of value-added business, and truly meet customer needs. The existing IP PBX has much open-source software, but Asterisk is undoubtedly the most famous, the largest use and most influential one of them. Its design goal is pure IP.This paper focuses on the theory of the VoIP and the enterprise applications of Asterisk system, and then it proposed three different VoIP communication system model based on different WAN traffic, the location of the call processing system and the size of the deployment. This thesis firstly introduces two main VoIP protocol - H.323 and SIP (Session Initiation Protocol) for research, analysis the principle and model of them, compares the difference between them and secondly does some research on the kernel of the soft-switching platform and the basic call process of Asterisk. At last, it set up two VoIP communication system models that based on soft-switching, and realized meeting system based on VoIP by these models. This telephone conference system can achieve some communication functions such as intra site's conference call and conference calls between different across sites according to the characteristics of single- site deployment model and multi- sites call- processing model (WAN distributed model).Finally this thesis makes a concluding outlook on the Asterisk existing problems and future development direction,particularly for the support and IAX on the existing platform for the further development of H.323, to meet the domestic demand more.