CAPI Design Of An ISDN Terminal Adapter Driver

This paper describes how to realize COMMON-ISDN-API (CAPI) and the layered driver for ISDN Terminal Adapter. Combined with CAPI specification, two different schemes are provided. At the same time, a specific realization method of each scheme is also introduced. According to CAPI specification, a new method used to realize CAPI is expatiated thoroughly, which lets software module supporting CAPI run in user model of Windows operation system. Also, how to develop Network Driver Interface Specification (NDIS) interface driver based on CAPI is given. Windows Driver Model (WDM) driver is a necessary part of the software based on these two schemes, the paper deals with the architecture of WDM driver according to our understanding of WDM in practice. The communication mechanism between application programs and the driver and the communication mechanism between different layers of the driver, which plays an extremely important role in the scheme, are also discussed at the end of the paper.Using the driver software based on these two schemes, the ISDN TA running with PC can be used to access the Internet with high speed, and to transmit voice and data etc.