No: 1 ESS System Organization and Objectives

l.i General The continuing expansion of present-day services, the demand for additional types of service, and the anticipation of new service offerings in the future all indicate a need for a new general-purpose switching system for the Bell System. The No. 1 electronic switching system (ESS) has been developed to meet this need. It is a general-purpose telephone switching machine capable of providing either two-wire or four-wire switching for local, toll, or tandem applications. No. 1 ESS provides today's services as well as several new ones, and is sufficiently flexible to provide for the ever-changing need for future services. It is economically competitive for present applications and will provide new services at relatively low cost. The purpose of this paper is to outline the objectives of the system and to provide a brief description as background for the several more 1831 1834 T H E BELL SYSTEM TECHNICAL JOURNAL, S E P T E M B E R 19G4 technical and more detailed papers which follow. Switching systems are, in general, complex and not easy to describe. No. 1 ESS not only entails many new concepts of switching system organization, but the equipment and apparatus used are also different from those of previous switching systems. As a consequence of this, No. 1 ESS is the largest development project ever undertaken by Bell Laboratories for the Bell System. The papers in this issue should give an adequate description of all the major concepts and techniques used in the system.