The goal of developing Integrated Mediation Device (IMD) is to reduce digital switching system's (DSS) workload for processing and generating various message, as well as providing a common switching interfaces for back-end application systems. A good application system should not only meet the client's requirements, but also consider the flexibility to meet the changes in the future. IMD is developed under this philosophy. All functions provided by the IMD system follows a popular standard Component Object Model (COM). For application systems and operation people that had to connect directly to the DSS to gather its output data, IMD offers several general IP-based services such as FTP and TELNET to them. In spite of switching system 5 heterogeneous interfaces such as RS-232、 X.25 or IP, the back-end systems just consider general IP interconnections. In other words, a lot of popular IP based software packages can be used to interactive with switching systems transparently via IMD. As for the security management issue, the IMD keeps the conversion log between the back-end application systems and users to switching systems. Basically, the IMD can be connected different types of switching systems by adopting a multi-function routers which have the capabilities of providing V.24、 V35 and RJ45 interfaces for physical layer and RS-232、 X.25 and Ethernet protocols for data link layer. The multi-function router must possess enough ports for connecting various media of DSS to get on backbone network through WAN or IP interface. In this way, it not only simplifies the connection method between the back-end application systems or users to the switching systems but also saves the cost of dedicated line connection for each application system. In addition, the IMD adopts a multiple routing policy for network fault tolerance consideration. The ATM network owned by CHT-L is the primary transmission route, and the CHT-Net is the backup solution. This article describes the IMD system functions, the software and the system architecture. It also explains the IMD system components, such as COM and SOCKET in details.