Research And Realization Of T.38 Real-time Facsimile Supported By IP-PBX

With its fast development during these years, the TCP/IP protocols based Internet has been the biggest network, carrying biggest scale of service and reaching every corner in the world. For its advantage of high efficiency in bandwidth use and low running cost, to transmit facsimile over IP network is becoming a new generation e-business service.On the other hand, for its versatility and flexibility, SIP (Sesssion Initialization protocol) has become the main stream among all the VoIP signaling protocols.Facsimile over IP (FoIP) is becoming the important component in IP communication Field because of the merit of high efficiency in bandwidth and low expenses. It falls into real-time FoIP and store-and-forward FoIP,which have respective advantages and shortcomings under different circumstances.Real-time FoIP is more attractive to users because of its short transmission delay and its traditional operation mode.So it has better application future.IP-PBX is a new generation communication server that breaks the traditional PBX mode. It has the positive meaning of advancing the level of technology and reducing communication cost between corporations by supporting T.38 real-time fax in IP-PBX. Combining SIP protocol and T.38 real-time facsimile communication standards,the dissertation gives a method of supporting T.38 real-time fax communication in SIPSYS IP-PBX. The extended IP-PBX not only supports the voice communication, but also supports the real-time facsimile communication between Group 3 facsimile equipments, really uniforms traditional telecommunication businesses to the SIPSYS IP-PBX. So the research has important value and wide application future.The dissertation starts with the basic principle of facsimile communication, expatiates the communication procedures between traditional G3 fax devices and real-time fax technologies. The dissertation also researches and analyzes the principle of the IP-PBX and T.38 real-time facsimile protocol. After comparing the main signal control protocols such as MGCP, H.323 and SIP, the dissertation expatiates the SIP/SDP protocol , and presents the call flow between gateways based on SIP/SDP protocol. Combining the T.38 protocol, the dissertation puts forward a system structure of T.38 facsimile realization in SIPSYS IP-PBX. In order to present the system design and implementation methods detailedly, we first give the general architecture, and more detailed depiction is covered in later chapters. According to the simple test results on the implemented prototype system, the system can be of practical value by given more optimizations.