The Access Of ISDN Terminals For IAD To The Soft Switch System

Nowadays, the PSTN (Public Switched Telephone Network)/ISDN (Integrated Services Digital Network) is being changed into NGN (Next Generation Network), and the PSTN/ISDN will coexist with NGN for a period of time. To telecom network, NGN indicates Softswitch system. With the development of NGN, the PSTN/ISDN terminals should be accessed to the Softswitch system. The PSTN/ISDN terminals include the analog terminals and the ISDN terminals. The inland IAD (Integrated Access Device) can access the analog terminals to NGN, but can' t access the ISDN terminals.The ISDN IAD that was researched in this thesis can accesse the ISDN terminals to NGN. It was achieved on the basis of analyzing the principle of IAD and the transmission model of the ISDN signaling in NGN. The effects of the research include as follows:The scheme for ISDN IAD was proposed. In this scheme, ISDN IAD was built based on the both of the software and hardware of IAD. ISDN chip was used instead of SLIC (Subscriber Line Interface Circuit) chip to connect the ISDN terminals to ISDN IAD. The IUA (ISDN Q. 921 User Adapter) protocol stack and the SCTP (Stream Control Transport Protocol) stack of TMG (Trunk Media Gateway) were reused. The device driver, the interface between the device driver and the Q921 module, as well as the module of medium gateway was also rebuilt.The structure—oriented method was adopted to design the module of signaling gateway. The module of signaling gateway, which was composed of the ISDN drive module, the Q921 module, the IUA module and the SCTP module, was implemented.For meeting the requirement of the ISDN service in NGN, the medium gateway module was modified after analyzing IAD. The call control function, which was completed by the signaling gatewaymodule, was combined with the connection control function, which was accomplished by the medium gateway module of IAD. Both signaling gateway module and the medium gateway module achieved the call flow. The medium gateway module of ISDN IAD was designed and implemented. The equip test technique of IAD which test chips by looping channel was used for reference. To combine it with the call flow specified by the Q931 protocol, the equip test scheme of simulating call for ISDN IAD was designed and achieved.