Voip Technology-based Pc-to-pc Phone System Realization

With the rapid development of the Internet technology, traditional applications over Internethave been gradually enlarged to multimedia applications, such as audio and video. It becomesmore and more popular for people to communicate by telephone over Internet. Today we not onlyresearch IP Phone itself,but also focus on IP multi-media communication and various IP Phoneapplications. Since VoIP develops quickly in the present telecommunication service, we shouldresearch thoroughly VoIP technology.The system is about the implementation of PC-to-PC IP telephone and is based on theresearch of VoIP technology. As one kind of voice communication technology based on IPnetwork, IP Phone technology possesses high transmission efficiency and low fee.In this paper, firstly, I summarize the principle of VoIP's implementation, explain severalforms of IP telephones, describe some technologies of Phone-to-Phone system and show the IPtelephone's merits. Subsequently, from the point of view of the system architecture and thefunctions, this paper describes the development process of PC-to-PC IP telephone in detail. Fourfunctions are implemented in this system: Firstly, collection and playing of voice;secondly,compression and decompression of voice data;thirdly, transportation of voice data on thenetwork;fourthly, multi-connections among users can be controlled. The IP Phone softwareachieves well predictive effect in practice. Moreover it makes the substantial base for furtherimproving the functions.This system is based on TCP/IP, adopting C/S structure. It runs on Windows 2000 operatingsystems and is achieved with VC++ 6.0.In the thesis, the system makes uses of low-grade audiofunctions. It adopts the UDP protocol to implement connectionless service. The application ofmulti-buffer technology can guarantee the continuity and QoS of audio transmission. Voice data'scompression and decompression are implemented by PCM. At the same time, all operations canbe executed at one time with multithreading.The system uses distributed control mode and realizes the intellectual clients. This is thesignificant innovation of this system, and it is important for further research about VoIPtechnology.In the end of the paper, I find through commenting on and expecting the system that IPPhone confronts with many problems and challenges and that People should further research andprobe into IP Phone to serve users.