The Research And Implementation Of SIP Trunking Gateway In IMS

With the development of Internet and voice technology, VoIP has held a very large part of the communication market recently. It becomes one of the most popular topics in the areas of Tele-communication and Computer Network. SIP is considered as one of the most important protocols in VoIP and the core technology in NGN and 3G, because of its good flexibility, simpleness and extensibility.In Release 5, 3GPP introduced IMS to the core network, which is much different from Softswitch in network architecture and interface. How to use the current VoIP endpoints in IMS becomes a very big issue. Furthermore, as there are still a large number of PSTN customers, the interworking between VoIP and PSTN becomes another big issue. SIP Trunking Gateway in IMS is the solution for the two issues above.Beginning with the key technologies in VoIP, this thesis introduces some important protocols and system architectures. Through the analysis of the interworking between PSTN and VoIP and the comparation between IMS and Softswitch, the research and implementation of SIP Trunking Gateway in IMS are talked in this paper.The emphasis of this paper is put on several issues which were encountered in the implementation of SIP Trunking Gateway, such as NAT Traversal for SIP, abstract call control and MGCP implementation.