The Research On Softswitch Technology And The Realization Of SIP Stack

The next generation network (NGN) with voice, data and multimedia services onjust one platform is the aim of the development of network technology. As the majortechnology of NGN, softswitch has put new ideas on the design of network, andimproved the realization of "three-network-in-one".Firstly, this paper investigates the architecture and the important parts ofsoftswitch network, and analyzes the functions and principles of softswitch, mediagateway and signaling gateway in detail, furthermore, introduces the framework ofproviding services in NGN.Secondly, this paper gives an in-depth analyzing of SIP protocol, which is one ofthe most important protocols of softswitch. SIP is used to found up, modify andterminate a dialog with one or several parties. Sofswitch components can interconnectwith each other easily by SIP. This paper takes an emphasis of SIP message form andSIP calling flows.Thirdly, with the specification of RFC 3261,this paper makes a detailed softwaredesign of UA part of SIP stack. The design follows the layering method, based on thelimit status machine of transactions, and eventually, realizes basic functions of SIPUA.Finally, this paper tests the software. Block testing aims at several importantparts and example testing emphasizes to check the functions of processing calls. As aconsequence of the tests, the SIP stack that this paper finished can meet therequirements that put forward by IETF according the functions of SIP protocol.