Based On Ims-based Pstn / Isdn Emulation Subsystem Design

With rapidly progress of communication and computer technologies, the packet switch technologies based on IP have been widely used. With the circuit switch, line utilization is low, and it is difficult to develop new services, thus we must research and develop new technologies. With the advent of IP multimedia subsystem(IMS), IP over circuit switch is achieved. Because IMS has a single call protocol(SIP), integrated framework, independently access, supports for multimedia, mobility, provides QoS assurance and open services, seamlessly aggregates heterogeneous networks, so IMS attracts international telecommunication standard groups and many big telecommunication manufacturers as long as IMS emerges. IMS has been one of principal technologies of next-generation networks(NGN),has huge application potential.Today, a great many of PSTN/ISDN circuit switch networks have been using. How to not only preserve existing equipments investment and but also make full use of wideband and service increment resulted from IP networks, circuit switch networks organically merges with IP networks, these problems and solutions are objectives of my thesis.Firstly, research the elements of PSTN/ISDN circuit switch networks, mainly including calling among exchanges,Numbering scheme (the specification E.164),signalling No.7 among exchanges and intelligent network services.Next, analyze IMS framework, track up-to-date ITU-T standards of IMS . I focuse on the core of IMS -control layer. Functionality and message structures of SIP, SIGTRAN, Diameter, COPS, H.248, are expounded. Simple flows of PSTN/ISDN networks accessing IMS networks and traditional terminals directly accessing IMS networks are designed. It is clear that main IMS functional modules and interdependency related with implementing of PSTN/ISDN simulating subsystem.Comprehending the elements of PSTN/ISDN circuit switch networks and IMS networks, and considering our special demands, design the scheme of implementing of PSTN/ISDN simulating subsystem based on IMS network frameworks. Action, position and application in networks, implementing scheme, of every equipment, is characterized by arranging a IMS functional module to corresponding equipment. Moreover, the three-level address architecture(private user identity, public user identity, network address) needed by network communications is presented. Authentication, IP address allocation, registering, call flows among all kinds of terminals, 800-service implementing, are depicted. Imagine three phases during this PSTN/ISDN networks gradually evolve to IMS networks. Simulating and experiments demonstrate the scheme of implementing of PSTN/ISDN simulating subsystem based on IMS network frameworks is feasible.