Bell System Practices

Bell System Practices


This is a random collection of [AT&T/Western Electric/Bellcore/Bell System/Northern Telecom/Nortel] Practices found by digging through garbage (literally) at central office and other telephone company locations around Wisconsin, various acts of undocumented telecommunication network exploration, or temporarily borrowing documents from telephone company vehicles for the good of all mankind.

Some are missing pages or were in poor condition to begin with.

Bell System Practices (BSPs) are documents authorized by AT&T Technologies, Inc., as the recommended instructions and criteria for planning, engineering, installing, operating, and maintaining telecommunications equipment and software products designed and manufactured by AT&T Technologies, Inc.  These practices also play an important part in the training of personnel.

A 9-digit (XXX-YYY-ZZZ) numbering plan is used for Bell System Practices with each practice being assigned a unique 9-digit number in accordance with the subject matter covered.  This plan permits organizing information into various categories to simplify and improve indexing.  This plan also provides a convenient means for ordering, distributing, and filing practices.

In the 9-digit numbering plan, the first three digits, XXX, identify major categories of information and are referred to as division numbers.  The fourth digit, xxx-Y, identifies a subdivision of a given category of information and is referred to as the layer number.  The fifth and sixth digits, xxx-yYY, represent a further breakdown and are referred to as sublayer numbers.  This scheme permits the breakdown of a division into subcategories of information.  The last three digits, xxx-yyy-ZZZ, identify individual practices within a grouping (layers and sublayers) and are referred to as key numbers.

The only key numbers that remain dedicated are the digits 900 through 999 in each division.  These key numbers have been reserved for numbering certain Bell Operating Telephone Company (OTC)-issued Bell System Practices.

Each BSP is assigned as issue number beginning with the number 1.  Each reissue is assigned the next higher number.  When issue 99 has been reached, the next issue will revert to issue 1.  Each BSP is dated and this data indicates the month in which this particular issue was released to the field.

Each BSP is given a rating  This rating appears in the page heading for page 1 and indicates how the Practice is circulated within the Bell System and how its contents must be treated.

To safeguard the Bell System Practice content and to ensure proper distribution, the following ratings are provided:

For example, the 231 division covers "No. 1 and No. 1A ESS Switches."  The second three digits specify the layer (subdivision); for example, 231-048 covers "2-Wire #1 and No. 1A ESS Switches Common Recent Change" practices.  The last three digits specify a particular practice; for example, 231-048-303 covers the "2-Wire No. 1 and No. 1A ESS Switches Trunk Recent Change Formats."

The types of AT&T practices used in a central office are: Descriptions, Operating Procedures, Test and Measurement Procedures, Maintenance Procedures, AT&T Task-Oriented Practices (TOPs), and Feature Documents.

The links in BOLD are black-and-white (300 dpi) scanned and OCRed PDF files of the original documents.

The PDF-to-HTML conversions were done using: "pdftotext -layout -htmlmeta" with pdftotext v0.18.4.

Any created HTML files were NOT edited for layout, formatting, non-text characters, etc. so the they not be very accurate and will probably display funny.

Files marked with (Incomplete) are missing lots of pages.

** = Were found on the Internet, local collections, or provided by others
## =
!! = <- Completely blows away my little collection!
?? =

Easter Eggs

  • No. 1A ESS Input Message: WHO-RU
  • No. 1A ESS Input Message: SPY-NOMORE
  • "We Really Mean It" bit/test.
  • "All-Seems-Well" transformer/circuit.
  • "High-and-Wet" trunk status.
  • BELLMAC-8 microprocessor (BELLMAC 32)
  • "!" is called the "ball bat" when used as an ESS Input Message end-of-message character.
  • "Ø" with a slash through it was used for the Latin character "O" instead of number zero ("0").

Looking For

  • 190-520-XXXX: COSMOS - Network Administration
  • 190-XXX-XXX: Any Practice from this Division
  • IM-6A001-01: No. 1A ESS Input Message Manual (Complete Original))
  • OM-6A001-01: No. 1A ESS Output Message Manual (Complete Original)
  • TG-1A: No. 1A ESS Translation Guide
  • PA-6A001: No. 1A ESS Office Parameter Specification
  • PA-6A002: No. 1A ESS Translation Output Configuration
  • 231-048-001: No. 1A ESS Basic Concepts of Translations
  • 231-048-312: No. 1A ESS RC:LINE
  • COSMOS Currents Newsletters
  • COSMOS Security Recommendations, by B. L. Cruse and E. L. Pinnes
  • COSMOS/FACS: 753-301-XXX, 753-303-XXX, 753-304-XXX, 753-307-XXX, 753-308-XXX, 753-310-XXX
  • LMOS: 660-168-XXX
  • MARCH: 190-537-XXX
  • PREMIS: 753-200-XXX, 753-290-XXX
  • SARTS: 666-610-XXX, 666-615-XXX
  • SARTS 2PC3 General Description: 666-610-100 (Issue #15, July 1993) - Includes craft access system description
  • SOAC: 753-303-XXX
  • SWITCH: 752-101-XX, 752-111-XXX
  • FOMS/FUSA Security Administration: 752-106-910
  • Any related technical/training manuals - COSMOS, SWITCH, FOMS, (L)FACS, WM, SOAC, MIZAR, MARCH, NetMemory, LMOS, MLT, SORD, PREMIS, CRIS, 1-2-3-4-5ESS, DMS100-250-500, etc.



Division 000

AT&T Practices - General Information

Division 005

Abbreviations, Definitions, Drawings, Requirement Tables, Specifications, and Symbols

Division 010

General Methods

Division 081

Outside Plant - Tools and Materials

Division 100

Test Equipment - Electrical Indicating Instruments and Meters (Common Usage) Maintenance, Selection, and Use

Division 105

PBX and Station Test Equipment

Division 106

Outside Plant - Electrical Test Equipment

Division 109


Division 190

Operations Support Systems - Operation, Maintenance, and Administration

Division 201

Central Offices Supplemental Information

Division 231

No. 1 & No. 1A ESS Switches

Division 235

5ESS Digital Switching System

Division 255


Division 363

Transmission and Signaling Systems - Pair Gain Systems

Division 460

General Information - Customer Equipment

Division 461

Wiring and Cable - Customer Equipment

Division 462

Drop and Block Wiring - Dedicated Plant and C Rural Wire

Division 463

Miscellaneous Station Apparatus for use with Station Installations - Customer Equipment

Division 502

Common Battery - Station Sets

Division 506

Coin Station Sets - Common Battery

Division 508

Booths, Shelves, Directories, Mountings, and Public Telephone Signs

Division 590

Data Systems - General Information

Division 620

Outside Plant - General

Division 621

Outside Plant - Pole Lines

Division 626

Outside Plant - Cable, Wire, and Apparatus General

Division 627

Outside Plant - Aerial Block and House Cable

Division 628

Outside Plant - Underground Cable

Division 629

Outside Plant - Buried Plant

Division 631

Outside Plant - Cable Terminals

Division 632

Outside Plant - Cable Splicing

Division 633

Outside Plant - Splice Closures

Division 634

Outside Plant - Electrical Cable Testing and Identification

Division 637

Outside Plant - Cable Pressure Systems

Division 638

Outside Plant - Electrical Protection and Bonding

Division 640

Outside Plant - Carrier Apparatus

Division 644

Outside Plant - Upkeep

Division 649

Outside Plant - Construction Equipment

Division 660

Test Center Operation

Indexes, Equipment Test Lists, and General Information

Division 666

Testboards and Test Positions for Special Services

Division 667

Test Center Operation - Switched Maintenance Access System (SMAS)

Division 752

Integrated Provisioning Mechanized Systems

Division 753

Information Systems - Loop Provisioning Mechanization

Division 936

Northern Telecom (Nortel) Documents

Miscellaneous Local Documents

Random collection of scanned telco documents, mostly for historical purposes.

Some may be Ameritech or Wisconsin specific, but should still be informative to the budding phreak.

Miscellaneous Internet Documents

Random collection of telco documents found on the Internet or provided by others.

Strom Carlson's Document Library

The content of this material is proprietary and constitutes a trade secret.  It is furnished pursuant to written agreements of instructions limiting the extent of disclosure. Its further disclosure in any form without written permission obtained through AT&TCo is prohibited.

Not for use or disclosure outside the AT&T Companies except under written agreement.

Not for use or disclosure outside the Bell System except under written agreement.

This document contains proprietary information of AT&T and is not to be disclosed or used except in accordance with applicable agreements.

This document contains proprietary information that shall be distributed or routed only within Bell Communications Research (Bellcore) and its authorized clients, except with written permission of Bellcore.

AT&T PROPRIETARY - This document contains proprietary information of AT&T and is not to be disclosed or used except in accordance with applicable contracts or agreements.

Pursuant to Judge Greene's Order of August 5, 1983, beginning on January 1, 1984, AT&T will cease to use "Bell" and the Bell symbol, with the exception as set forth in that Order.  Pursuant thereto, any reference to "BELL" and/or the BELL symbol in this document is hereby deleted and "expunged."  :(

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