The Research And Realization Of Server And PC Terminal Based On VoIP Communication System

Recently, VoIP has become one of the application services that develops at the fastest speed in telecommunication industry for its low price and high efficiency of using Internet and so on. As the most important protocol and one of the most mature technological protocols of VoIP, H.323 has been one of the most common applied protocols of VoIP.This paper analyzes the system framework of H.323 as well as some key techniques of VoIP, and the VoIP communication system based on H.323 has been designed and realized. It consists of three parts: the server, the PC terminal and the embedded terminal. In this design, some improvements have been achieved in authentication process of H.323, the security of VoIP communication system has been researched, and the MD5 encryption arithmetic, with the purpose of insuring the security of user's information, has been replanted. Furthermore, some new ways for the realization of text communication and FVR have been tried. With the ability of charging real-time, the function of gatekeeper is integrated in the server of this system, therefore, the registered and on-line users can be administrated conveniently. Furthermore, high efficiency and low-bit rate codec algorithm has been embedded in the terminal of this system, which promotes the transmission capability and saves the network resource. With some additive functions, such as address list, communication record, speech hint as well as modification of personal information, the smooth speech communication and reliable text communication between PC terminal and embedded terminal have been actualized.According to the test, the system's parameters, such as speech and delay have reached the requirement of H.323 protocol standard. With good expansibility and stability, the software has a nice operation interface. This system can be used to study VoIP communication protocol and some key techniques, such as speech code, mute restraint, real-time transmission, network security, network administration, and so on. Besides, it can be used to explore methods for realizing commercial VoIP.