Design And Implementation Of A Generic Signal Control Module For VoIP Access Gateway

With the rapid development of optical communication and digital transmission technology, some bottleneck problems such as bandwidth and QoS in digital communication network have been resolved and various IP technology oriented applications are widely in use. As a typical IP application, VoIP gains much attention and development with the trend of broadband and real-time application.As a critical part of the VoIP system, VoIP gateway was widely used to supply cheap VoIP application and value-added service based on VoIP for various network subscribers. Because of the numerous signal protocols in the current VoIP field and physical media access methods in gateways are diverse, a generic implement of signal control module will be meaningful in practice usage. That makes it easy to realize the interoperability between different communication networks and signal systems.In this thesis, based on the in-depth analysis of the VoIP business prospects and the current mainstream VoIP signal protocols, the author analyzed the signal call flows and flow characteristics of some common, and then in the background of the the actual demand of the VoIP gateway project, the author brought forward a generic implement of common signal control scheme. Then, the author introduced the software architecture of the termination module in VoIP gateway, some functions and the designs of them were depicted in detail; also the design of the important state machine was analyzed. Among that, the signal transition between the inter signal system inside the module and other signal protocols or access interfaces were emphasized. Further, the author have designed some test schemes to validate its capability, the result on different test topology present this generic signal control module matched the requirement of the VoIP gateway project quite well.The usage of this generic signal control module has been adopted in residential gateway project and video conference system project already. The result and practice has proved that it is a portable solution and applicable in various situations.