Based On The Research And Design Of The Sip-voip Terminal

At present,SIP technology is still in developing phase,but when SIP technology becomes matured and marketed step by step,it will arise an unprecedented revolution in the telecommunication field and provide better value-added service to all walks life;and SIP protocol will gradually become the core protocol of VoIP technology instead of H323 because of its lower complexity and better expansibility,so VoIP system based on SIP represents the application trend of the future communication technology.In this paper,deep study was performed on SIP protocol of VoIP signaling technology,and on this basis a VoIP application system based on SIP protocol was designed and developed.Along with the continuous development of speech transmission operation of IP block net,especially the comprehensive application of IP telephone in the global,a large numbers of gateway products with more powerful functions are needed in the market,such shows rather realistic significance for the research and development of the related products of this field.In this paper,at first the work principle and key technology of VoIP was described,and the detailed analysis was performed on the system structure and protocol buildup of SIP network,and VoIP network using SIP technology was analyzed.Then aiming at the demand of routine official business and operation communication for the interior of enterprise,in this paper VoIP system based on SIP was designed.This system performed session control by SIP message,the system used SIP protocol to perform session control,SDP performed information description,RTP performed the media stream transmission,and RTCP performed the media stream control.Since developing integrated SIP protocol was a rather complex project,during the process of realization of terminal system,transmitting the existing eXoSIP was used to realize the function of SIP.In general the system structure of VoIP was divided into speech processing module,network processing module and user exchanging module,its main functions were to provide the functions such as registration,authentication,call establishment and withdraw,call rejection and speech communication,etc,among them,the speech communication was transmitted by RTP protocol,and the other functions were realized by SIP signaling.In the realization of the software,in order to simplify the control process of SIP signaling, the user agent module structure based the operation state machine mode was suggested,thereby causing having simplified the signaling processing process, encoded and implemented the audio frequency acquision and release for VoIP terminal software,the compression and encoding of the terminal software,and the video and voice transmission.After testing,the terminal cuold perform good control on signaling and show good inter communication.