Softphone Sip-based Voice And Implementation

When roughly in 1995, the first voip examples have appeared in the world first to use TCP/IP protocal to carry out voice communication software. This IP telephone is to adopt H.323 generally all, the service is level managing mechanism like tradition telephone-like classification, but often difficult to fuse with internet service.But with NGN times arrival, Internet tends in providing still more much better added value service, Internet interface now for the simplicity and isomerism platform, major part have all adopt text-based communication protocol,for example,HTTP , SMTP Protocal to win enormous success on Internet for instance.Under such background, the SIP (Session initial Protocol) protocol has appeared.this protocol is from similar HTTP brought forward by IETF ((Internet Engineering Task Force)) , is to communication very simple. Internet easy to draw is integrated, boundary having broken a region.The SIP protocal is a new agreement , gives Internet-based VoIP system to have poured the new vigour in. Therefore, the SIP agreement and relevance technology research apply value to having a pole at present highly , are also future new area VoIP system realization key technology.Introduction the main body of a book has been carried out on the VoIP concept and the technology first systematically and go deep into the position having discussed that VoIP system hits the target in NGN.Then, the main body of a book have analysed SIP agreement structure , information form, order method, and process sequence such as linking up , registering detailedly. And, the agreement has also carried out the explanation introducing a sum on relevance RTP.Base above,this issue explaned realization of SIP software phone,include data structure,class,process event,voice gather ,voice compress and send .Finally,I make a testing for this sip phone and Analyse merits and demerits.