NTP
                          NTP 297-1001-100                   PAGE 1
                         PREL., ISSUE 01D03
                              79 09 21



  1.   INTRODUCTION


  GENERAL

  1.01   The DMS-100 Family of  digital multiplex switching systems
  consists  of a  series of  modular, software-controlled,  digital
  central office switches, providing local and/or toll service with
  a  variety  of  optional features.   The  particular  package  of
  services and features, specified by the customer, is assembled by
  selecting types and  quantities of hardware and  software modules
  from the DMS-100  Family range of products.   The following basic
  types and capacities of switches are available.

³      (a)  DMS-100.   A local central office, having a capacity of
³           1500 to more than 100,000 subscriber lines.

       (b)  DMS-200.  A  toll central  office, capable  of handling
            from 400 to 60,000 trunks of various types.

       (c)  DMS-100/200.    A   local  and  toll   central  office,
            handling combinations  of subscriber lines  and trunks,
            within the ranges  of (a) and (b), and  as specified by
            the customer.

       (d)  DMS-300.   An International  (Gateway) switching center
            capable of handling up to 25,000 international trunks.


  BASIC CONFIGURATION (Figure 1)

  1.02   All types  of DMS-100 Family switches have  the same basic
  configuration,  consisting of  four  main  functional areas;  the
  Central Control Complex  (CCC) area, the Switching  Network (NET)
  area, the Peripheral  Modules (PM) area, and  the maintenance and
  administration area.

  1.03   The CCC  and NET areas perform the same  functions for all
  DMS-100 Family switches, but the PM  area varies depending on the
  type of switch.  The PM provide interfaces between the  NET and a
  variety of external  facilities, such as analog  subscriber lines
  (DMS-100),  analog trunks  or DS1  digital  trunks (DMS-200),  or
  international   trunks  (DMS-300)   to  the   standards  of   the
  International  Telephone  and  Telegraph  Consultative  Committee
  (CCITT).  The types of PM are selected to meet the specifications
  of the switch.

  1.04   The components of the  maintenance and administration area
  vary depending on  the features required by the  customer and the
  type of switch.






                  DMS-100 FAMILY SYSTEM DESCRIPTION
                 (c) NORTHERN TELECOM LIMITED, 1978


                          NTP 297-1001-100                   PAGE 2
                         PREL., ISSUE 01D03
                              79 09 21



  REFERENCES

³ 1.05   The following  documents contain detailed  descriptions of
³ items mentioned in this practice.

³      (a)  Northern_Telecom_Practices

³           DMS-100 Family Central Control
³           Description                             NTP 297-1001-101
³           DMS-100 Family Switching Network        NTP 297-1001-102
³           DMS-100 Family Peripheral Modules       NTP 297-1001-103
³           Internal Message Handling               NTP 297-1001-104
³           Maintenance System                      NTP 297-1001-106
³           Software System                         NTP 297-1001-108
³           Maintenance and Administration Position NTP 297-1001-110
³           DMS-100 Family Traffic Provisioning     NTP 297-1001-450


³      (b)  General_Specifications

³           Central Processing Unit                 GS1X41
³           Memory Module                           GS3X31
³           Central Message Controller              GS1X32
³           Trunk Module                            GS2X52
³           Digital Carrier Module                  GS2X31
³           Maintenance and Administrative Position GS0X57
³           Line Module                             GS0X45
³           Network Module                          GS0X48
³           Software System Structure               GS1V00
³           I/O Controller                          GS1X61


























                  DMS-100 FAMILY SYSTEM DESCRIPTION
                  (c) NORTHERN TELECOM LIMITED, 1978