Designation And Realization Of T38 Fax In Media Gateway

Real-time FoIP(Fax over IP), born from the combined technology of IP and traditional facsimile communication, with the advantages of real time, easy operation, low cost and so on, has good prospect. Traditionally, the function of FoIP is realized in the voice gateway, which has too many functions to deploy the IP telephony system in large scale. As a result, the idea of gateway separation is presented: Voice gateway is divided into Media Gateway(MG),Media Gateway Controller(MGC) ,signaling Gateway(SG). Based on this separation, next generation network framework (NGN) with the main technology of soft switch is generated.The author attended the software development of Fax over IP module which is based on NGN in a company of Shen Zhen. The main work concerned includes:1. The protocols used in the Real-time FoIP communication are analyzed, and the main job includes: The communication procedures between the facsimile terminal and the gateway based on the recommendation T.30; the communication procedures between gateways based on the recommendation T.38; the call establishment procedures between gateways based on H.323 and the call establishment procedures between gateways based H.248 in the soft switch network.2. There isn't a uniform standard for FoIP based on NGN. In connection with this situation, the author gave out some FoIP flows. Those flows could suit for different media gateways and soft switches which differ in ability of supporting FoIP.3. The author attended the requirement analysis and overall design of FoIP, accomplished test and part of coding. The details of job done here include: Adding process of FoIP flow in service module, adding management of DSP resource which have T38 ability, adding configuration of those parameters which associated with FoIP, adding alert about abnormal of FoIP, and accomplishing test of T38 Fax quality.