Pragmatic Introduction of Digital Switching and Transmission in Existing Networks

Introduction of digital Switching and transmission in existing networks depends on a multiplicity of factors, which are either network or system dependent. Digital network planning alternatives are discussed with reference to the introduction techniques (stand alone or integrated switching and transmission) and to the interconnection strategies with the analog network. A pragmatic approach with distributed tandem exchanges is proposed, and various network scenarios are presented with reference to different starting points including toll, local tandem, rural area and local terminal levels. A possible transition scenario for a progressive implementation of Integrated Service Digital Networks (ISDN) is also indicated. Finally, the main features and advantages of the pragmatic approach are presented.