As the hub of multimedia networks in office environment, EPBX (Electronic Private Branch Exchange) systems will need to evolve to support diverse voice and data services and various network and terminal protocols, and also to respond to growing traffic demand. Research has been conducted to enhance CPU performance in order to develop a load-sharing, super-large-capacity EPBX system with more than 4,000 lines which is capable of handling massive volumes of traffic in the multimedia age. This load-sharing, super-large-capacity EPBX system is equipped with a newly developed multiprocessor control system and a higher-speed interprocessor bus control architecture conforming to the industry's de facto standards. This paper discusses the technological aspects -performance and functionality- of the new super-large-capacity multiprocessor EPBX system.