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The DMS-100 is a member of the Digital Multiplex System (DMS) product line of telephone exchange switches manufactured by Northern Telecom. Designed during the 1970s and released in 1979, it can control 100,000 telephone lines. [1] The purpose of the DMS-100 Switch is to provide local service and connections to the PSTN public
DMS-100 (large local digital Class 5) (also known as an SL-100 when used as CPE (Customer Provided Equipment or PBX service) also known as Centrex. A Nortel DMS-100e used by an operator to offer local and long-distance services in France; DMS-100/200 (local/toll digital more than 135,000 lines) DMS-200 (toll digital)
A typical volume of Bell System Practices from the 1970s. The Bell System Practices (BSPs) is a compilation of technical publications which describes the best methods of engineering, constructing, installing, and maintaining the telephone plant of the Bell System under direction of AT&T and Bell Telephone Laboratories. [1]
Centrex is a portmanteau of central exchange, a kind of telephone exchange. It provides functions similar to a PBX, but is provisioned with equipment owned by, and located at, the telephone company premises. [1] Centrex service was first installed in the early 1960s in New York's financial district by New York Telephone.
The 5ESS switch has three main types of modules: the Administrative Module (AM) contains the central computers; the Communications Module (CM) is the central time-divided switch of the system; and the Switching Module (SM) makes up the majority of the equipment in most exchanges.
There are also Model 100 and Model 200 3B2 systems. [1] The 3B2/600, [3] running at 18 MHz, offers an improvement in performance and capacity: it features a SCSI controller for the 60 MB QIC tape and two internal full-height disk drives. The 600 is approximately twice as tall as a 400, and is oriented with the tape and floppy disk drives ...
Also taking advantage of the superior versatility of 5XB, Centrex was invented as a service package. Later stored program control exchanges allowed more extensive service features. Autovon originally used a four-wire version of 5XB, with a more complex marker to implement its nonhierarchical polygrid routing system.
Although POTS provides limited features, low bandwidth, and no mobile capabilities, it provides greater reliability than other telephony systems (mobile phone, VoIP, etc.). Many telephone service providers attempt to achieve dial-tone availability and more than 99.999% of the time, the telephone is taken off-hook.