Design And Implementation Of Signalling Exchange Software Of SIPG Gateway

SIP/PSTN gateway is a device which interworks between IP network and PSTN.The traditional architecture of SIP/PSTN gateway needs DSPs to implement Codec etc functions.This article introduces SIPG which is a low cost SIP/PSTN gateway,and SIPG uses generic processors and software to take the place of DSPs to implement the functions,so this reduces costs efficiently and improves performance/cost ratio.SIPG is the production of SIP/PSTN gateway which is based on this architecture, and the signalling exchange software of SIPG gateway is the core of SIPG.Signalling in PSTN network is usually Digital Subscriber Signalling System No.1 (DSS1) of ISDN,and SIP protocol controls the session in IP network.And it is different for two protocols in call flow and message formats,so it needs gateway devices between IP network and PSTN network to support both Digital Subscriber Signalling System No.1 (DSS1) of ISDN using in PSTN and SIP protocol.The function of signalling exchange software of SIP/PSTN gateway is exchange two signallings.The signalling exchange software of SIPG gateway can be used to build the SIP/PSTN gateway solution which is low cost and high performance/cost ratio.This thesis discusses the design and implementation of signalling exchange software of SIPG gateway. Chapter 1 introduces the relative technology of the SIP/PSTN gateway and basic principles of the SIP protocol,and it introduces the link layer specification Q.921 and network layer specification Q.931 of Digital Subscriber Signalling System No.1 (DSS1).Then this thesis analyses the principles of signalling exchange software and defines the concepts of abstraction layer of signalling and channel in chapter 2.And in chapter 3, this thesis discusses the design of the architecture of signalling exchange software of SIPG gateway,the design of channel,the design of SIP protocol,and the design of ISDN protocol. Chapter 4 discusses the implementation of signalling exchange software of SIPG. The signalling exchange software of SIPG gateway is implemented using C language using object-oriented programming thought. Chapter 5 discusses the testing for the signalling exchange software of SIPG gateway, and SIPG has passed a serial of testing and worked well.