Design and Implementation of a Pilot ISDN

Integrated Services Digital Networks (ISDN) will play an increasingly important role in the field of communications in the coming few decades. This paper discusses the design and implementation of a pilot narrowband ISDN. A personal computer (PC) based ISDN user terminal and a time/space switch with the facility for the transmission of voice (at 64 kb/s) and data (at 64 kb/s or 16 kb/s) have been designed and tested. The overall configuration tested includes three PC based user terminals and the time/space switch. The implementation consists of the hardware and software for ISDN layers 1, 2 and 3. The software covers the signalling precedures and Link Access Procedures on the D channel (LAPD). Full implementation is according to the recommendations specified by CCITT in the Red Book [1] and in particular it covers the recommendations I.430, I.440 and I.450.