Research And Implemention Of The Embedded VoIP Gateway Based On H.323 Protocol

With the development and popularity of Internet, the VoIP technology which is based on it has also been widely applied in our life. With this technology, IP Phone is bringing strong impact and challenge to the traditional circuit-switched telephone, because it has great advantage in the cost of long-distance calls(especially Overseas Calls).Today VoIP is becoming a hotspot in the service of many telecom operators.VoIP, which is also called IP Phone, is a communication way of transmitting voice by IP network. It converts the analog voice signal to digital, and then the signal is compressed and packed to transmit on Internet. Gateway is the key equipment which is used to communicate between PSTN and IP network, the telephone number we dial is mapped to an IP address by this equipment. In addition, gateway also transforms the data format and translates the protocol between PSTN and IP network, as well as promotes the popularity of IP Phone service, so IP Phone has not been limited on PC.In this dissertation, a kind of embedded VoIP gateway based on H.323 protocol has been designed and implemented, and some parts in detail. At the beginning the background and significance of this project is summarized, and the principle and key technology of VoIP are introduced; then a mature VoIP standard, the H.323 protocol, is analyzed to study its structure of signal and full process of a call. With the basicknowledge about the embedded system, our design—S3C4510B+AC483+uClinux(VxWorks), including hardware and software, is explained. The author's main work is transplanting Openh323 protocol stack to the embedded platforms and testing its stability, providing Command Line Interface function for the protocol stack and driver, finishing the structure design,procedure design and coding of the Serial Port Communication Module, which is also joined with the Flash Reading and Writing Module to make the configuration saved when electricity is cut off and loaded when turned on. Finally the project is summarized on the whole, and the bright future of VoIP technology is showed.