System Design of Digital Telephone Switching System - NEAX 61

This paper describes the design objectives and system structure of the NEAX 61 Digital Telephone Switching System, newly developed by Nippon Electric Co., Ltd. The NEAX 61 is an extremely wide-coverage system in both its application range and capacity range. Furthermore, the system's unique structure allows it to be highly costefficient at any size and in any of its applications. NEAX 61 is distinguished by the following features: (1) Fully stored program controlled, PCM time-division switch, utilizing a 4-stage, T-S-S-T switching network. (2) Modular building-block structure for both hardware and software. (3) Separation between "core" switching subsystem and application subsystem, and interface standardization of the above subsystems. (4) Solid-state four-wire line concentration stage employment for economization and zero intraoffice transmission loss realization. (5) Available in both North American and CEPT configurations, meeting applicable CCITT, REA, and USITA/ATT requirements.