Design Of An ISDN Terminal Application Layer Software

The paper is focus on the design of the application layer software of an ISDN TE (Terminal Equipment) for purpose of providing various and flexible application for ISDN users .A scheme is given that the application layer software of an ISDN TE bases on the TAPI(Telephony Application Programming Interface)provided by Microsoft's Windows. And three programs (Data Link Test, State Indication of B Channel and Disposal of Call Waiting) are implemented according to the scheme. Data Link Test checks the link between TE and switch. State Indication of B Channel Software gives notice to user the state of two B channels. Disposal of Call Waiting Software is used in the case that a new call request arrives when the 2B channels are used to access Internet. A new method is adopted in the implementation of Data Link Test Software. This paper gives a presentation on TAPI and the principle of designing application layer software in detail. The reliability, stability and flexible scalability of the software is verified in practice.