This paper presents an overview of the 5ESS 7 " system architecture. The administrative, communications, and switching modules are described, together with an overall view of the software architecture. Operations and maintenance aspects and a short discussion of evolutionary trends are covered.

The 5ESS™ switching system is a digital, time-division switching system that is being introduced into a multiplicity of operating environments-local, toll, private networks, and stand-alone applications. Many of these operating environments are currently dominated by analog, space-division switching systems. Furthermore, the 5ESS switching system is being introduced into environments in which there have been increasing trends toward centralization and mechanization of operating procedures through the use of minicomputerbased support systems. The 5ESS switching system has been designed to allow a smooth incorporation into these mechanized operating environments, while still retaining features needed for stand-alone operations in less mechanized environments. This paper describes the operational features, both administrative and maintenance, of the 5ESS switching system. The emphasis is on the features that differ from those of earlier stored program control switching systems. These include features that represent enhancements over those of earlier systems, differences mandated by a digital, time-division technology, and features designed to more readily adapt to operations support systems.