The Design And Implemention Of SIP Application Server

With the development of the technology and progress of the society, people's need for the communication is increasing rapidly. The users hope to use rich and wonderful services. IMS, regarded as the trend of the network, separates the services from call controlling and call controlling from payload, thereby implementing a relatively independent service architecture. In that case, the services and networks can develop respectively, so the services can be developed flexibly to meet the increasing need for services. The SIP application server, located in the application layer of the IMS network system, is the native service provider of the IMS and it will become the main method to provide value-added services. The SIP AS takes charge of executing and managing various value-added services, handling the interface protocols between CSCF and AS. Rich and flexible services can be provided to the end users by the application server.This paper introduces the background knowledge of the IMS network system initially, and then introduces the concept and functionalities of the application server and some related technologies in detail. Based on that, the author expatiates the IMS SIP application server's architecture, and some key problems of the implementing, including the design and implementing the SIP stack, the encapsulation of the application layer and developing the server's applications. At last, the author also discusses some key techniques of the SIP protocol stack.