Design Of VoIP Gateway Based On DSP

A kind of VoIP system based on computer network has been designed. This VoIP system used computer network by soft-switch technical, not only save maintenance costs, but also make the good use of computer network's bandwidth resource. This VoIP system already could realize the telephone communication between enterprise interior users, but cannot communicate with the users of PSTN. Therefore, we have to develop a VoIP Gateway to realize the telephone communication between VoIP system users and PSTN users.This paper developed a kind of network telephone gateway based on local computer network by using soft-switch technical. The VoIP Gateway designed proposal based on DSP chip has been raised. DSP chip TMS320C5402 and CPLD chip EPM240T100C5N were used to design the hardware circuit, includes main controller module, ring circuit relaying module, DTMF receive and transfer module, busy tone detection module, Enthernet interface module, memorizer module, and so on. Formulated the WMGCP calling controller protocol by optimize the MGCP protocol. Using C language programed the VoIP Gateway software, included main function, WMGCP calling controller subprogram, UDP/IP communication subprogram and bottom chip drive subprogram. Made the model machine and carried out the experiment. This VoIP Gateway had media mapping, calling control and insert the core network function. Finally achieve the telephone communication between VoIP communication system users and PSTN users.This VoIP Gateway used advance technology, had good capability and low cost. Not only can used in enterprises, but also can used in education, technology, electronic, bank and public security system. It has remarkable economic efficiency and the social efficiency.