Design And Prototype Implementation Of Conference Application Server Based On SIP

SIP is a multimedia session control protocol for IP network. Replacing H.323, SIP will be the basic protocol in developing next-generation Internet multimedia applications because it can take advantage of NGN and 3G. Since SIP doesn't support network conference directly and there is no an applied network conference system based on SIP, it is valuable and necessary to implement it.The research is carried out under such a background. In this thesis we firstly give a brief introduction about the development and key technologies of network conference. Then we present our actual design based on SIP, conference appliacation server, which adopts distributed architecture, signaling and media stream are separated totally, so it has high flexibility and scalability.The conference application server is composed of two parts: conference control server and conference media server. In this thesis, we introduce the design and implementation of the entire conference appliacation server in detail. The conference control server is control core in the conference application server, which processes all the signaling between user agents and conference appliacation servers, the detailed signaling flows and implementation are given in this thesis. The conference media server provides media processing functions, such as audio media stream transport, encoding, decoding, mixing, etc.On the foundation of the asterisk project which is open source under Linux OS, we successfully implemented the prototype system of the conference application server based on SIP and SIP extensions, according to RFC3261 and some relevant drafts. The prototype system can communicate with standard SIP UA, providing audio conference service for users. The prototype system has a good generality and can be easy to expand for super-large commercial conference.