Research And Implementation Of VoIP-TETRA Signaling Gateway Based On SIP

In the research fields of communication and network, with its advantages, such as simpleness, efficiency, easy extendibility and so on, now SIP protocol becomes the mainstream control protocol in the field of VoIP. TETRA digital trunked communication system has its advantages including better compatibility, fine openness, powerful confidentiality and so on. It is a digital trunked standard which is presently the best established, and involving the most manufacturers all over the world. In view of the important status and the current broad prospects of SIP and TETRA in the field of network and communication, the interconnection between TETRA system and SIP-based VoIP system will become a trend.At present, the interconnection between SIP and PSTN has its corresponding SIP-T standards, and the interconnection between TETRA and PSTN also has its corresponding standards. However, there are no corresponding standards proposed for the interconnection between SIP and TETRA. Therefore, it has great significance of researching and implementing SIP-based VoIP-TETRA gateway.Firstly, this paper summarizes the characteristics of SIP protocol and TETRA digital trunked technology and their research situation at home and abroad, and analyzes the network structure and function of SIP system and TETRA digital trunked system. Based on the signaling mechanism and working mode of the two systems, this paper introduces the design scheme of the gateway architecture, the mappings of signaling and the procedure of signaling interconnection between SIP and TETRA. The gateway connects SIP network and TETRA network by imitating the form of base station, and defines Az interface information as the way of communication with TETRA network. Then based on the mapping relationship of signaling, the gateway completes the transformation and transmission for SIP messages and TETRA signalings, and successfully achieves the call establishment according to the procedure of signaling interconnection. And then the gateway is achieved from two aspects of system platform and application development. For the application development, the task design and program development are implemented by using the open eXosip/oSIP protocol stack. Finally, by unit tests and system functional tests of the gateway, the implementation scheme of the signaling gateway between SIP and TETRA is verified, which provides a reference for future study.