AOH :: P19-03.TXT

Digital Multiplexing Systems (Part 2)

                               ==Phrack Inc.==

                     Volume Two, Issue 19, Phile #3 of 8

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|_|                                                                       |_|
|_|              Understanding the Digital Multiplexing System            |_|
|_|                                (Part2)                                |_|
|_|                                                                       |_|
|_|                                   by                                  |_|
|_|                                                                       |_|
|_|                                Control C                              |_|
|_|                                                                       |_|
|_|                                   &                                   |_|
|_|                                                                       |_|
|_|                        The Tribunal Of Knowledge                      |_|
|_|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_|

  Well some of you may recall my file on Digital Multiplexing in Phrack 10.
Well this is part 2 that was promised about a year and a half ago.  I was
finished with this file in May of 87 and I just decided to release it now.
Here it is!

  DMS switches were first introduced in 1979, since then it has been modified
to interface numerous types of switches.  DMS has the ability to interface
with SP-1, #5 XBar, 1ESS, 2ESS, 3ESS, 4ESS, NX1D, NX1E, TSD, SXS, ETS4, NO. 1
EAC, NO. 2 EAX, NO. 3 EAX, TSPS, CAMA/3CL boards, Stromberg Carlson Turret of
ONI and Visual Indicators, Modified North Electric TSD for ONI, Stomberg
Carlson (CAMA operator Position - ONI/ANI), AE #31 Switchboard, Co-located
NT/AE switchboard I/C, O/G, UDC data poller of OM, DACS (Directory Assistance
Charging System), NT #144 LTD, WECO #14 LTD, WECO #16 LTD, CALRS (Centralized
Automated Loop Reporting System), Badger 612A, AE #1 and #21 LTD, AE #30, SC
#14 LTD, Lordel MITS70 line Test System, Porta System Line Test Unit, Pulsar
II IMTS, Teradyne loop test unit, and the WECO MLT 1 (Mechanized Loop Testing

Common Channel Interoffice Signaling

  Common Channel Interoffice Signaling (CCIS) is a way of signaling and a way
of implementing network level services. CCIS provides reliable, crystal clear
data signaling links between the network and the switching offices.  The CCIS
signaling method uses transmission equipment that is separate from voice

Common Channel Interoffice Signaling No. 6

  The basis for the CCIS system is the International Consultative Committee on
Telephone and Telegraph (CCITT) No. 6 international standard, which is brought
to it's fullest capacity for use in the Stored Program Control (SPC) network
of AT&T.

  The CCIS6 network contains a bunch of signaling regions, each having a pair
of interconnected Signal Transfer Points (STP).  The switching systems put
into CCIS6 then connecting to STPs are called Serving Offices (SO).

  Band Signaling (CCIS-BS) is used on trunk signaling for intertoll-type
trunks using the CCIS network.

  Direct Signaling (CCIS-DS) is used for signaling between SPC switching
machines and a Network Control Point (NCP).  At the present time CCIS6 can
handle Enhanced INWATS Originating Screening Office (OSO), Calling Card
Validation (CCV), Mechanized Calling Card Service (MCCS), and Billed Number
Screening (BNS).  CCIS6 is available with DMS-100/200, DMS-200, and
DMS-100/200 or DMS-200 with TOPS.

CCIS6 Diagram:
                                            NSB        ST
                      ------------         - - - - - - - - - - -
          DTC        |            |      |            -------    |
         - - -  DS30 |    IPML    | DS30 |  - - -    | ||    |   |
--------|     |------|- - - - - - |------|-|     |---| ||    |   |
Digital  - - -       |            |      |  - - -    | ||    |   |
Trunks               |            |      |           | ||    |   |
                     |            |      |            -------    |
                     |            |        - - - - - - -|- - - -
          DTC        |            |          TM         |
  DIG    - - -  DS30 |    NUC     |  DS30   - - -      -----
--------|     |------|- - - - - - |--------|     |----|     |
^        - - -       |Network     |         - - -      -----
CCIS         \        ------------                     Modem
Signaling     \            |
           - - -         -----
AN Links--|     |       | CCC |
           - - -         -----


        DIG - Digital
        AN - Analog
        DTC - Digital Trunk Controller
        MSB - Message Switch Buffer
        ST - Signaling Terminal
        TM - Trunk Module
        NUC - Nailed-Up Connection
        IPML - Inter-Peripheral Message Link

Common Channel Interoffice Signaling No. 7

   Common Channel Signaling (CCS) No. 7 or CCIS7 is a CCS system bases on
CCITT No. 7.  CCIS7/CCS7 on the DMS switch consists of two parts the Message
Transfer Part (MTP) and the Interim Telephone user Part.  They are compatible
with DMS-100, DMS-200, DMS-100/200, and DMS-100/DMS-100/200 with TOPS.

   CCIS7 can't tell the difference between banded and direct signaling.  CCIS7
uses Destination/Origination Point Codes (DPC/OPC) to rout back to the switch.

   CCIS7 can handle Automatic Calling Card Service (ACCS), Enhanced INWATS,
Local Area Signaling Services, and Direct Service Dialing Capabilities.

Equal Access

  The DMS-200 Access Tandem (AT) gives a traffic concentration and
distribution function for interLATA traffic originating and a distribution
function for interLATA traffic origination or terminating inside a Local
Access and Transport Area (LATA). This gives the interLATA Carrier (IC) access
to more that one end office inside the LATA.  It can handle InterLata Carrier
access codes (10xxx), 10xxx and 950-yxxx dialing, Automatic Number
Identification (ANI) on all calls, answer supervision, equal access Automatic
Message Accounting (AMA) for both originating and terminating calls, and
operator service signaling.

   The DMS-100 EA gives direct and tandem switched access service inside the
LATA for originating and terminating to interLATA Carriers.  It is available
in the following three ways:

Equal Access End Office (EAEO)

  DMS-100 Equal Access End Office (EAEO) gives a direct interconnection to
interLATA Carriers (IC) and international Carriers (INCs) Point of Presence
(POP) inside the LATA.

Access Tandem with Equal Access End Office

  The DMS-200 Access Tandem (AT) when used with equal access end office (EAEO)
lets trunk tandem interconnect to ICs/INCs POP inside the LATA.

   The connection of the Equal Access End Office (EAEO) to an IC/INC through
the DMS-200 Access Tandem (AT) uses what is called two-stage overlap output
pulsing which makes the time it takes to set up a call quicker.  The AT uses
the digits OZZ + XXX out pulsed  in the first stage to identify the IC/INC
dialed and to pick and outgoing trunk.  Then a connection is established from
the IC/INC to the EAEO through the AT.  The second stage digits, consist of
ANI and the called numbers are passed through the DMS- 200 AT at the IC/INC.

   A AMA terminating record in AT&T format is produced by the DMS-200 for all
the EAEOs.  A per call terminating AMA record is made for calls that get to
the stage where the trunk from the IC/INC has been seized and a "wink" has
been returned by the DMS-200 AT.

Access Tandem with a Non-Equal Access End Office

   DMS-200 AT using a non-equal access end office gives trunk tandem
connection to an IC/INC POP within the LATA.  To set up a call, connection of
Feature Group B (FGB) or Feature Group C (FGC) End Office to an IC/INC through
the DMS-200 AT, uses the standard Bell Central Automatic Message Accounting
(CAMA) signaling.  The Access Tandem uses the XXX digits of the access code
950-YXXX out pulsed from the FGB end office to identify the IC/INC and to
connect to a outgoing trunk.

Mechanized Calling Card Service (MCCS)

   The fraudulent use of calling cards, third number and collect calls and the
increasing movement to automate current operator services has directly led to
the implantation of the Mechanized Calling Card Service (MCCS) to DMS-200/TOPS
and to the remote and host Operator Centralization (OC).

   MCCS uses CCIS to relay queries and responses to and from the DMS-200/TOPS.
Operator handled calling card calls and the direct entry by subscribers of
Calling Cards by DTMF (Touch-Tones) telephones are given special provisions by
the MCCS.  Both, the operator handling and the direct entry of calling card
calls, are decreasing the size operators.

   Billed Number Screening (BNS) gives an enhancement to the operator-handled
collect and third-number billing by using CCIS to screen a number at the
billing validation data base for billing restrictions (i.e. the third number
is a fortress).  This feature naturally will reduce fraudulent use of the
collect call feature.

   Common Channel Interoffice Signalling-Direct Signalling (CCIS-DS), which is
the feature that the MCCS is designed around, is used to transmit messages to
and from many possible Billing Validation Centers (BVCs).  Messages
transmitted to the BVC about MCCS include the billing number and the Personal
Identification Number (PIN).  In BNS the messages have the special billing
number (collect or third number).  The return messages from the BVC include
validity (of the number), billing restrictions (if any), and the Revenue
Accounting Office (RAO) code.

Auxiliary Operator Services System

   The DMS-200 Auxiliary Operator Services System (AOSS) is used primarily for
Directory Assistance and the intercept needs that are not included in the TOPS
package.  The AOSS is similar to TOPS and co-exist with TOPS on the DMS-200
Toll system.

   Major benefits of the AOSS include Directory Assistance is provided with a
modern environment, AOSS position administrative activities are performed by
the DMS-200 toll maintenance system, trunking savings are achieved by
combining trunking for 1+ and 0+, and Directory Assistance traffic, DA
services are managed by using TOPS methods, Creation of a built-in training
system, which does not require additional training equipment and reduces
training costs.

Integrated Business Network

   The Integrated Business Network (IBN) is a revenue-producing concept
designed for small and big businesses to offer modernized PBX and Centrex
features.  The Operating Company can use the IBN to maintain and enhance its
competitive position on a operational DMS-100 and DMS 100/200 switches.
While using the DMS-100 switch, the Operating Company can support varying
business features along with existing local/toll traffic.

   IBN services can be introduced to a Centrex-Central Office (CO) or a
Centrex-Customer Unit (CCU) by additional software modules and minor hardware

   Current IBN features include:  A growing system that can handle 30,000
lines, networking capabilities, city wide service for DMS- 100 switch and
remotes for any one customer station Message Detail Recording (SMDR), which
gives IBN customers call records. The records can be used for system analysis
and control and station charge-back.  SMDR can use LAMA records, if the IBN
host has LAMA equipment, Centralized attendant maintenance and administration
functions and Direct Inward Dialing (DID).

Electronic Switched Network (ESN)

   The Electronic Switched Network is designed to meet the telecommunication
needs of large multi-location corporations. The ESN is made up of a SL-1 or
SL-100 Digital Business Communications System with networking features or a
DMS-100 IBN host.  The SL-1 can handle from 30-5000 lines.  The SL-100 and the
DMS-100 IBN hosts can hold from a few thousands to 30,000 lines.

   A DMS-100 IBN or SL-100 can remotely serve many locations from the host
site.  This is done by a connection through digital transmission facilities
which are set up at remote modules at the subscriber's premises.

Specialized Common Carrier Service (SCCS)

   The DMS-250 Specialized Common Carrier Service (SCCS) provides the
capability of Analog to Digital (A/D) and Digital to Analog (A/D) conversions
which are necessary with analog circuits. The DMS-250 can also switch voice
and data circuits.

   The DMS-250 takes either analog or digitally encoded info and by using time
slot interchange, switches it from any input port to a temporary addressed and
connected exit port.  The info may or may not be converted back to analog.

Normal Private Telecommunications Network Diagram:

           -----               ------
 [Phone]--| SnS |             | SL-1 |-[Phone]
          | PBX |             | PBX  |
           -----               ------
           |  |DOD/DID   DOD/DID|  |
           |   -------   -------   |
           |Tie       | |       Tie|
           |Trunk  ---------  Trunk|
            ------| Class-5 |------
              ----| Centrex |----
             |     ---------     |
             |                   |
             |                   |
             |                   |
           -----  Tie Trunk  ---------
          | SnS | ----------| Class-5 |
          | PBX |           | Centrex |
           -----             ---------
             |                   |
             |                   |
             |                   |
             |                   |
          -------             ------
 [Phone]-| Small |           | SL-1 |-[Phone]
         |  PBX  |           |      |
          -------             ------

Cellular Mobile Radio Service

   A cellular system consists of two main parts a cellular switch and cell
site equipment.

Cellular Switching Systems

   A cellular switch performs three main functions audio switching, cell site
control, and system administration.

   The DMS switches provide three basic implementations for cellular switching
Stand-alone, Combined, and Remote.

   Stand-alone switching is done by a Mobile Telephone Exchange (MTX) which is
interfaced with one or more class 5 end offices.  The connection is made by
DID/DOD trunks.  Depending on the needs of the area, the MTX can be divided as
follows:  MTX which serves urban areas, MTXC which handles suburban areas, and
MTXM which is used for rural areas.

   Combined switching is incorporated into a DMS-100 by some hardware
additions and cellular software.  Combined switching is designed to give a
easy, cost-effective way to install cellular services to an existing host.

   Remote Switching is done by combining Remote Switching Center (RSC) with a
Cell Site Controller (CSC).  This combination is hosted by either a
stand-alone or a combined switch.  Remote Switching is designed for serving
suburban centers, remote areas, or a small community and it gives extra
flexibility for a growing system.

   All of these cellular switches have the ability to balance the workload
among various cell sites.  For example, if one site's workload reaches the
programmable level of congestion, calls would be routed to nearby sites that
can handle the extra calls.

Cell Site Equipment

   Cell site equipment consists of a CSC and radio equipment. The CSC is
controlled by the cellular switch and it controls radio equipment and
maintenance tasks.  The CSC will work on any MTX cellular switch because of
the Remote Cluster Controller (RCC).

   The radio equipment consists of self-contained Radio Channel Units (RCU),
antennas, transmitter multi-couplers and receiver combiners.

   By different program software a RCU can perform voice, control locating,
and test functions.  The self contained nature allows the RCU be remotely
located to the CSC. A RCU has built-in circuitry for extended testing of the
radio part of the system.

           --------                               ----------
[phone]--| Remote |                             | SL-1 PBX |--[phone]
         | Module |                             | ESN Main |
          --------                               ----------
              |                                       |
              |  DS-1 Facility                        |  DS-1 Facility
              |            --------------             |
               -------->  | Local Class 5|  <---------
          [phone]---------|    DMS-100   |
                      ----|    IBN/ESN   |-------------
        2W Loop MFIDP |    --------------             | ESN Trunk Group
           or DS-1    |           |                   |     or DS-1
                      |         -----         ---------------
                      |        | CSC |       | Local Class 5 |
                   --------     -----        |    DMS-100    |
                  | SL-100 | <--- DS-1 ----> |    IBN/ESN    |
                   --------     Facility  Ph  ---------------
                      |                              |
                      |                              |
                      | DS-1 Facility                | DS-1 Facility
                      |                              |
                   --------                      ----------
         [phone]--| Remote |                    | SL-1 PBX |--[phone]
                  | Module |                    | ESN Main |
                   --------                      ----------

<End of File>

If you have any questions contact me or any other member of the T0K!

              Control C
               !T0K! (1987)

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