Design And Implementation Of SIP And Its Extension On IPPBX

With the bloom of Internet and the development of IP technology and VoIP technology, VoIP products are now having a rising market of the telecommunication, VoIP technology becomes one of the most popular topic in computing and telecommunication field. Because of the good feature such as simpleness, flexibility and extensibility, SIP becomes one of the most important technologies in VoIP and considered the key technology in the Next Generation Network technology.Traditional PBXs played a very important role in the telecommunication field, till now they are the most often used for communication in enterprise. But the traditional PBXs are based on private technology and lacks of open standards, have shortages in flexibility and extensibility, needs high cost for maintenance and upgrade. These shortages of the traditional PBXs lead to the birth of the IP technology based PBX. With the development and mature of VoIP technology, IPPBX will play an important role in the telecommunication's future.This paper is to illustrate the design and implementation of the SIP protocol and its extension, with the project experience which the author participated in—The Development of "VL-IPX5200" Series IPPBX. This paper will introduce VoIP and its key technology and their architecture compare several signaling protocol of VoIP, introduce IPPBX's system architecture. The emphasis of this paper is the illustration of the design and implementation of SIP signaling module and call control module of the IPPBX, and supplementary services that are accomplished by SIP's extension is illustrated in detailed. In the last part of the paper, functional test and pressure test of IPPBX is presented with results.