DMS-100
The DMS-100 is a member of the Digital Multiplex System (DMS) product line of telephone exchange switches manufactured by Northern Telecom.
[1] The purpose of the DMS-100 Switch is to provide local service and connections to the PSTN public telephone network.
Much of the hardware used in the DMS-100, with the possible exception of the line cards, is used in other members of the DMS family, including the DMS-200 toll switch.
[2] The NT1X47 card also contained the 2-digit hexadecimal display to indicate test result codes and the condition of the core.
The NT1X48 processor maintenance card contained a thumbwheel on the faceplate to enable various diagnostic tests of the CPU.
A later modification of these same five circuit boards with faster pin-compatible discrete logic devices enabled the CPU to operate at 40 MHz allowing central offices to improve call throughput capacity by 10 percent.
The Compute Module contains redundant SuperNode CPUs to handle call processing and maintenance functions and, like the NT40 core, can operate in a synchronized mode with its mate.
The Message Switches of the DMS Bus operate in a load-sharing mode and one of them provides the main clock source for the DMS-100 system while the others are synchronized to it.
The operating system used by both generations of the DMS-100 switch was called Support Operating System (SOS) and was written in a high level language called PROTEL which stood for PRocedure Oriented Type Enforcing Language developed at Bell Northern Research (BNR).
[6] Hardware and maintenance are administered locally through cathode-ray terminals, through a multilevel menu system called MAPCI.
LMs were not able to send caller-id information (CLASS services) and became rare late in the century, having been supplemented or replaced by the newer Line Concentrating Module (LCM).
The NT6X18 also has the ability to provide current reversal required for some coin phones and business systems.
The NT6X17B and the NT6X18B is known as the world line card and is software configurable to more than 15 million functional settings to meet almost any signalling and transmission requirement in any market.
Type NT6X21 cards serve P-sets (Meridian Business Sets), a special analogue telephone with a proprietary Nortel data link operating at 8 kHz to provide advanced call handling services.
Back then they needed two 'boxes' to work- a host box called a Central Terminal (CT) that had the dial tone lines wired into it and a remote box called a Remote terminal (RT) where the dial tone 'came out'.
As telcos modernized, these remote boxes were re-configured to work directly from a SMU peripheral at the host DMS.
In 2006 Nortel introduced the Communication Server 1500 (CS 1500) Softswitch based on VOIP to modernize the DMS-based telephone switches.
[9] In 2010, Genband purchased Nortel Networks' Carrier VoIP and Application Solutions (CVAS) business for $182.5 million.
