Digital Multiplex System

Digital Multiplex System (DMS) is the name shared among several different telephony product lines from Nortel Networks for wireline and wireless operators. Among them are the DMS-1 (originally named the DMS-256) Rural/Urban digital loop carrier, DMS-10 telephone switch, the DMS SuperNode family of telephone switches (DMS-100, DMS-200, DMS-250, DMS-300, DMS-500, DMS-GSP, DMS-MSC, DMS-MTX), and the S/DMS optical transmission system.

Exploratory development on the technology began at Northern Telecom's Bell Northern Research Labs (Ottawa, Canada) in 1971. The first Class 5 switch, the DMS-10, began service on 21 October 1977 in Fort White, Florida and the first toll switch (Class 4), the DMS-200, entered service in 1979 in Ottawa, Canada. The DMS-10 was the first commercially successful Class 5 digital switch in the North American market and had a profound impact on the industry. Of the numerous digital switching products introduced in the North American telephone market in the late 1970s, only the Nortel DMS family is still in production. GENBAND acquired Nortel CVAS assets including the DMS line in 2011 and rolled it into its IP-based GENiUS platform. The GENiUS-750nt is the first product to include adaptive nano-tech compression and resynchronization modules from Ericsson, to replace the digital cross-connect (DCS) in place since the earliest DMS releases.

Previously, new technology had entered the telecommunications industry slowly, with the telephone companies amortizing equipment over periods as long as forty years. AT&T was intending to delay the introduction of digital switching until the 1990s. The DMS, with its introduction of digital technology, changed the industry and became one of the antecedents that encouraged the growth of the Internet.

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