This paper describes the NEAX®2400 Information Management System (IMS), which is no longer a conventional telephone switching system, but is instead a switching hub for various office automation equipment. The NEAX2400 IMS not only provides various circuit-switching functions such as conventional voice communication (telephone) switching, low-speed and high-speed data switching, but also provides stored and forward capabilities for voice (voice mail) and data (text mail, facsimile mail, etc.). This paper especially emphasizes the basic EPBX features and functions of the NEAX2400 IMS. The standard 64 kbit/s PCM technique is used for digitalization of voice signals, and switched through a nonblocking architecture time-division digital network. All digital data signals are transmitted through the same time-division digital network at the 64 kbit/s rate intermixed with digital voice signals. The controls of the switching functions, station service features, and maintenance service are performed by functionally divided distributed microprocessers. The most outstanding attribute of the NEAX2400 IMS is the unique building-block architecture of the equipment configuration. Modules are stacked above the basic module as the number of line and trunk ports, or additional stored and forward features are required. Up to four additional modules can be stacked up as a single module group. This unique arrangement permits the NEAX2400 IMS to be very flexible in its system applications and expandability. Practically, the NEAX2400 IMS will economically service as few as 184 ports (mixture of voice/data, line/trunk) and can be continuously expanded to as many as 23 184 ports.

The Universal Link System belongs to the "loop subsystem" of a local area network (LAN). This system has circuit-switching facilities and packet-switching facilities, and uses a local area network as an integrated switching system. The Universal Link System is well suited for a very wide range of uses, with the merits of both circuit switching and packet switching. The Outline of this system is described below.

This concise paper reports the result of a study on a multiplexing scheme for digital data transmission and switching which can handle both anisochronous and isochronous data traffic of various mix, mainly in one digital channel of PCM primary multiplex level (e.g., 1544 kbits/s) and corresponding time-division switch (TDSW) of data-switching equipment. The study aims to determine a unified scheme which is economical and flexible for intercity heavy-traffic data links, to accommodate a wide range of data speeds. The paper describes various multiplexing schemes and analyzes their features in terms of frame structure, synchronization time, error-correction capability, compatibility with signaling, hardware complexity, etc. A bit-interleaved multiplexing scheme is chosen as suitable and is applied in a laboratory model of a digital data switching system, the DDX-1 System.