AT&T DS1, DMi, ISDN-PRI User Manual

AT&T

DEFINITY

AT&T 555-025-101 April 1990

Communications System

Issue 4

and System 75 and System 85

DS1/DMI/ISDN-PRI Reference

NOTICE

While reasonable efforts were made to ensure that the information

in this document was complete and accurate at the time of printing,

AT&T can assume no responsibility for any errors.

Changes or corrections to the information contained in this

document may be incorporated into future issues.

Prepared by

AT&T Technical Publications Department

Denver, Colorado

Printed in USA

CONTENTS

ABOUT THIS DOCUMENT

PURPOSE

INTENDED AUDIENCES

PREREQUISITE SKILLS AND KNOWLEDGE

HOW THIS DOCUMENT IS ORGANIZED

HOW TO USE THIS DOCUMENT

TRADEMARKS AND SERVICE MARKS

RELATED SOURCES

HOW TO MAKE COMMENTS ABOUT THIS DOCUMENT

1. INTRODUCTION

FUNDAMENTALS OF DS1 SIGNALS

Channels

Framing Formats

Signaling Types

Line-Coding Formats

IMPORTANT CONCEPTS

Common-Channel Signaling

Alternate Voice/Data (AVD) Trunks

Bearer Capability (BC)

ISDN Call Processing

CBC Service Selection

Networking Restrictions and ISDN-PRI Limitations

xix

xx xx

xx xxii xxii xxii

xxiii

1-1

1-7 1-10 1-14 1-16 1-22 1-22 1-22 1-23 1-25 1-28 1-29

2. NETWORK CONNECTIONS AND CONFIGURATIONS

NETWORK DIFFICULTIES

Hyperactivity

Glare

2-1

2-2

iii

iv CONTENTS

DS1/DMI PRIVATE-NETWORK CONNECTIONS

Generic 1, Generic 2, System 75, or System 85 to Another System

Host Computer to Another System

IDNX Multiplexer to Another System

IBM

Other Vendor Digital Switch to Another System

Analog Switch to Another System

OPS to Another System Via a D4-Channel Bank

DS1/DMI PUBLIC-NETWORK CONNECTIONS

4ESS to Another System (Special-Access Connection)

5ESS to Another System

DACS to Another System

Analog CO to Another System Via a D4-Channel Bank

DS1/DMI TERMINAL-EQUIPMENT CONNECTIONS

CDM

CEM to a BCM32000

ISDN-PRI PRIVATE-NETWORK CONNECTIONS

System 85 R2 to a System 85 R2V4, Generic 1, or Generic 2

System 85 or Generic 2 ISDN-PRI to Another Vendor’s Digital Switch

ISDN-PRI PUBLIC-NETWORK CONNECTIONS

2-3 2-3 2-3 2-4 2-4 2-5 2-5 2-6 2-6 2-7 2-8 2-8 2-9

2-9 2-10 2-12 2-12 2-13 2-13

System 85 R2V4, Generic 1, and Generic 2 to a 4ESS

Synchronization

System 85 R2V4, Generic 1, or Generic 2 to a DACS

System 85 or Generic 2 ISDN-PRI to a 5ESS

3. DS1 TRANSMISSION AND CABLING

METALLIC CABLING OPTIONS

DSX-1 Distance Limitations

Network Channel Terminating Equipment (NCTE)

On-Premises Cabling

Off-Premises Cabling

NONMETALLIC CABLING OPTIONS

CEM AND CDM CABLING CONFIGURATIONS

LINE EQUALIZER AND COMPENSATION SETTINGS

2-13 2-15 2-15 2-15

3-1

3-2

3-3

3-5

3-6

3-7

3-9

CONTENTS

System 85 Traditional Modules

Generic 1 and Generic 2 Universal Modules

4. THE DIGITAL LOSS PLAN

LOSS-PLAN IMPLEMENTATION AND PROVISIONING

Generic 2

Generic 1

PORT-TO-PORT LOSS VALUES

DS1/DMI/ISDN-PRI PORT LOSSES

TERMINATING A DS1 AT A CHANNEL BANK

Tie Trunk Ports

CO DID Trunk Ports

OPS Ports

5. SYNCHRONIZATION OF DIGITAL FACILITIES

THE NEED FOR SYNCHRONIZATION

SYNCHRONIZATION HIERARCHY

System 85 and Generic 2 Synchronization Architecture

System 85 and Generic 2 Synchronization Software Operation

CHANGES TO THE SCS SOFTWARE MADE AVAILABLE VIA SOFTWARE PATCHES

System 75 and Generic 1 Synchronization Architecture

System 75 and Generic 1 Synchronization Software Operation

The External Synchronization Clock

3-9 3-9

4-1

4-2 4-2 4-3 4-4 4-6 4-6 4-6 4-6 4-7

5-1

5-1 5-3 5-7

5-9 5-11 5-11 5-12 5-14

NETWORK SYNCHRONIZATION AND ENGINEERING

Selecting a Timing Source for the Switch

Internal Reference Selection Rules

External-Reference Selection Rules

AVAILABILITY OF SYNCHRONIZATION SOURCES

CONCLUSIONS ON SYNCHRONIZATION

USE OF GENERIC 2 AS A SYSTEM CLOCK REFERENCE

ISDN-PRI Trunk Facilities (ANN35 or TN767 with TN755)

Line-Only Mode DS1/DMI-BOS (ANN11_ or TN767)

5-18 5-18 5-19 5-27 5-28 5-29 5-29 5-29 5-29

CONTENTS

Line+Trunk Mode DS1/DMI-BOS (ANN35 or TN767 with TN555)

DMI-MOS (ANN35 or TN767 with TN755)

USE OF GENERIC 1 AS A SYSTEM CLOCK REFERENCE

Trunk-Mode ISDN-PRI (TN767)

Trunk-Mode Interface (ISDN-PRI + Robbed Bit) (TN767)

Line-Only Mode DS1/DMI-BOS (TN767)

Trunk-Mode DS1/DMI-MOS (TN767)

6. PORT TYPES/INSTALLATION COMPATIBILITIES

GENERIC 1 DS1/DMI-BOS

Operating Mode

Supported Port Types

GENERIC 1 ISDN-PRI

SYSTEM 85 DS1, TRADITIONAL MODULES (ANN11)

Operating Modes

Line+Trunk Mode Port Grouping Rules

Supported Port Types

SYSTEM 85 DS1 OR DMI-MOS, TRADITIONAL MODULES (ANN35)

Operating Mode

Port Grouping Rules

Supported Port Types

5-30 5-30 5-30 5-30 5-30 5-31 5-31

6-1

6-4 6-4 6-4 6-5 6-5

6-5 6-10 6-10 6-13 6-13 6-14 6-14

7. ADMINISTRATION OPTIONS AND REQUIREMENTS

SYSTEM 85 (R2V1 THROUGH R2V4)

Procedure 275 Word 4:

Procedure 276 Word 1:

Procedure 250 Word 1:

Procedure 260 Word 1:

Procedure 262 Word 1:

Procedure 354 Word 3:

Procedure 000 Word 4:

Procedure 210 Word 2:

ISDN Service — Enable/Disable

Other Feature Groups

DS1 — Carrier Designation

DS1/DMI/ISDN-PRI Physical Interface

ISDN Board Parameters

NPA-NXX Digits Assignment

NPA-NXX Index Designator

LDN, NPA, and NNX Attendant Partition Assignments

7-1

7-3

7-4

7-6 7-16 7-18 7-19 7-20

CONTENTS

vii

Procedure 010 Word 4:

Procedure 100 Word 1:

Procedure 100 Word 2:

Procedure 100 Word 3:

Procedure 101 Word 1:

Procedure 103 Word 1:

Procedure 116 Word 1:

Procedure 012 Word 1:

Procedure 012 Word 2:

Procedure 012 Word 3:

Procedure 309 Word 1:

Procedure 309 Word 5:

Procedure 321 Word 1:

Procedure 321 Word 5:

Procedure 107 Word 1:

Procedure 108 Word 1:

GENERIC 2

Line Side (B-Channel) BC and ISDN Routing Options

Trunk Group Type, Signaling, and Dial Access (ID) Code

Trunk Group Data Translations

ISDN Trunk Group Signaling Options

ISDN Trunk Group, SMDR, Digital Loss Plan, and AVD Assignments

Trunk Group Digit Collection and Trunk-Side BC

DS1/DMI/ISDN-PRI Trunk Assignments

Name Database

ARS Assignments and IXC/ISDN Network Identifier

ARS and ISDN Trunk — Network Characteristics

AAR Assignments and IXC/ISDN Network Identifier

AAR and ISDN Trunk — Network Characteristics

ISDN Trunk Verification by Terminal, Attendant, and ATMS

ISDN Trunk Group Terminating Test Line Number (Digits)

7-22 7-23 7-26 7-27 7-30 7-33 7-35 7-38 7-40 7-41 7-42 7-44 7-46 7-47 7-48 7-49 7-51

Procedure 275 Word 4:

Procedure 276 Word 1:

Procedure 250 Word 1:

Procedure 260 Word 1:

Procedure 262 Word 1:

Procedure 262 Word 2:

Procedure 262 Word 3:

Procedure 280 Word 1:

Procedure 354 Word 3:

Procedure 000 Word 4:

Procedure 210 Word 2:

Procedure 014 Word 1:

Procedure 014 Word 2:

Procedure 010 Word 4:

Procedure 100 Word 1:

Procedure 100 Word 2:

Procedure 100 Word 3:

ISDN Service — Enable/Disable

Other Feature Groups

SC/DS1 — Carrier Designation

DS1/DM1/ISDN-PRI Physical Interface

Additional DMI-MOS/ISDN-PRI Facility Options

ISDN-PRI D-Channel Backup

ISDN-PRI Codeset Map Assignments

ISDN-PRI Receive/Transmit Codeset Mapping

NPA-NXX Digits Assignment

NPA-NXX Index Designator

LDN, NPA, and NNX Attendant Partition Assignments

BCCOS Routing Options

BCCOS Data Options

Line Side (B-Channel) BC and ISDN Routing Options

Trunk Group Type Signaling and Dial Access (ID) Code

Trunk Group Data Translations

ISDN Trunk Group Signaling Options

7-51 7-52 7-53 7-54 7-65 7-67 7-69 7-71 7-72 7-74 7-75 7-76 7-78 7-80 7-81 7-84 7-86

viii

CONTENTS

Procedure 101 Word 1:

Procedure 103 Word 1:

Procedure 116 Word 1:

Procedure 012 Word 1:

Procedure 012 Word 2:

Procedure 012 Word 3:

Procedure 279 Word 1:

Procedure 309 Word 1:

Procedure 309 Word 5:

Procedure 321 Word 1:

Procedure 321 Word 5:

Procedure 107 Word 1:

Procedure 108 Word 1:

SYSTEM 75 (R1V2 AND R1V3)

Network Synchronization Options

Trunk Group/Trunk Group Members

GENERIC 1

Network Synchronization Options — DS1 and ISDN-PRI Applications

Trunk Group/Trunk Group Members — DS1 Trunk Applications

Processor Interface Data Module — ISDN-PRI Applications

Processor Channel Assignments — ISDN-PRI Applications

Interface Links — ISDN-PRI Applications

Trunking Considerations — ISDN-PRI Applications

Network Facilities — ISDN-PRI Applications

Trunk Group — ISDN-PRI Trunk Applications

Trunk Group Usage Allocation — ISDN-PRI Applications

Usage Allocation Plan Assignment Schedule — ISDN-PRI Applications

Trunk Group Member Assignments — ISDN-PRI Trunk Applications

SID Prefix Table — ISDN-PRI Applications

Routing Patterns — ISDN-PRI Applications

Hunt Group — ISDN-PRI Applications

ISDN Trunk Group, CDR, and Digital Loss Plan

Network Trunk Group Translations

DS1/DMI/ISDN-PRI Trunk Assignments

Name Database

Network Facilities Coding

ARS Route Tables

ARS–ISDN BCCOS

AAR Tables (Generic 2)

AAR–ISDN and Other Feature Parameters

ISDN Trunk Verification by Terminal, Attendant, and ATMS

ISDN Trunk Group TTL Number (Digits)

7-88

7-90

7-92

7-94

7-95

7-96

7-97 7-100 7-101 7-102 7-104 7-105 7-106 7-107 7-110 7-112 7-115 7-119 7-121 7-124 7-125 7-126 7-128 7-129 7-130 7-139 7-141 7-143 7-144 7-146 7-149

Terminating Extension Group — ISDN-PRI Applications

7-150

CONTENTS

8. MAINTENANCE AND ALARMS

GENERIC 1 AND GENERIC 2 ISDN-PRI MAINTENANCE PHILOSOPHY

GENERIC 2 MAINTENANCE CAPABILITIES AND CONCERNS

Generic 2 Maintenance Procedures

Summary of Generic 2 Maintenance Capabilities

GENERIC 1 MAINTENANCE CAPABILITIES AND CONCERNS

Generic 1 Maintenance Procedures

Summary of Generic 1 Maintenance Capabilities

ALARMS

Circuit Pack Alarms

Facility Alarms

A. ADMINISTRATION REQUIREMENTS

B. SAMPLE INSTALLATION AND MAINTENANCE PROBLEMS

8-1

8-1 8-1 8-2 8-5 8-6 8-6 8-7 8-7 8-7 8-8

A-1

B-1

TRANSLATIONS-BASED PROBLEMS

TRUNKS AND TRUNK GROUPS

CDMs

CEMs

D4-Channel Banks

SYNCHRONIZATION-RELATED PROBLEMS

Loss of or No Synchronization

Leavenworth Loop

D4 Synchronization Problems

Digital CO Synchronization Problems

DACS

TYPICAL PHYSICAL INTERFACE CONNECTION PROBLEMS

Specific Cabling Options

System 85 DS1/DMI to System 85 DS1/DMI — Colocated Arrangement

System 85 DS1/DMI to System 75 DS1/DMI — Colocated Arrangement

System 85 DMI to Host Computer

System 85 DS1/DMI Direct to a NCTE

B-1 B-3 B-5 B-5 B-7 B-8 B-9

B-9 B-10 B-12 B-12 B-13 B-17 B-18 B-20 B-21 B-22

CONTENTS

System 85 DS1/DMI-BOS to a CEM or CDM

C. ADMINISTRATIVE PROCEDURE SUMMARY

PROCEDURE 000 WORD 3 (Generic 2 Only)

PROCEDURE 000 WORD 4 (System 85 R2V4 & Generic 2)

PROCEDURE 010 WORD 4 (System 85 R2V4 & Generic 2)

ISDN Routing Parameters (System 85 R2V4 & Generic 2)

BC (System 85 R2V4 Only)

PROCEDURE 012 (System 85 R2V4 & Generic 2)

PROCEDURE 100 WORD 1 (System 85 R2V4 & Generic 2)

PROCEDURE 100 WORD 2 (Generic 2 Only)

PROCEDURE 100 WORD 3 (System 85 R2V4 & Generic 2)

PROCEDURE 103

PROCEDURE 107 WORD 1 (System 85 R2V4 & Generic 2)

PROCEDURE 108 WORD 1 (System 85 R2V4 & Generic 2)

PROCEDURE 116 WORD 1 (System 85 R2V4 & Generic 2)

B-22

C-1

C-1 C-3 C-3 C-3 C-4 C-5 C-5 C-6 C-7 C-7 C-8 C-9 C-9

PROCEDURE 210 WORD 2 (System 85 R2V4 & Generic 2)

PROCEDURE 260 WORD 1 (System 85 R2V4 & Generic 2)

PROCEDURE 262 WORD 1 (System 85 R2V4 & Generic 2)

PROCEDURE 262 WORD 3 (Generic 2 Only)

PROCEDURE 275 WORD 4 (System 85 R2V4 & Generic 2)

PROCEDURE 279 WORD 1 (Generic 2 Only)

PROCEDURE 280 WORD 1 (Generic 2 Only)

PROCEDURE 309 WORD 5 (System 85 R2V4 & Generic 2)

Field 4, ISDN Trunk Type

Field 5, Network Service Value

BC (System 85 R2V4 and Generic 2)

PROCEDURE 321 WORD 5 (System 85 R2V4 & Generic 2)

PROCEDURE 354 WORD 3 (System 85 R2V4 & Generic 2)

PROCEDURE 420 (System 85 R2V4 & Generic 2)

C-9 C-9

C-9 C-11 C-11 C-11 C-11 C-13 C-13 C-13 C-16 C-17 C-17 C-18

D. TRUNK TYPE AND SIGNALING TYPE COMPATIBILITY

TABLES

CONTENTS

D-1

ABBREVIATIONS

GLOSSARY

INDEX

AB-1

GL-1

IN-1

xii

CONTENTS

LIST OF FIGURES

Figure 1-1. Figure 1-2. Figure 1-3. Figure 1-4. Figure 1-5. Figure 1-6. Figure 1-7.

Figure 1-8. Figure 1-9. Figure 3-1. Figure 3-2. Figure 3-3. Figure 3-4. Figure 4-1.

Figure 5-1. Figure 5-2. Figure 5-3. Figure 5-4. Figure 5-5.

Figure 5-6. Figure 5-7. Figure 5-8. Figure 5-9.

Figure 5-10. Figure 5-11. Figure 5-12. Figure 5-13. Figure 5-14. Figure 5-15. Figure 5-16.

System 85 R2V4 ISDN Configuration Generic 2 ISDN Network Configuration Generic 1 ISDN Network Configuration D4 Framing DS1 Extended Superframe Format DS1 Signal, Framing Format, and ESF Superframe (24 Frames) Alternate Mark Inversion Example of B8ZS Line Coding ISDN Message Signaling Format On-Premises Metallic-Cable Configurations Off-Premises Metallic Cable Configuration Nonmetallic Cabling Configurations CEM and CDM Cable Configurations End-to-End Loss Configuration Using Combination Tie Trunks Options for Synchronization Synchronization Hierarchy Stratum Levels for the Synchronization Hierarchy SCS (Generic 2) Duplicated Synchronization Architecture and Cross Coupling Tone-Clock Synchronizer (Nonduplicated, Generic 1) Public-Network External Clock External Clock External-Clock Interface External-Clock Duplicated Synchronization External and Internal Reference Levels Nonpublic Network without Digital Switches Proper Use of Backup Facilities Improper Use of Backup Facilities Optimal Diverse Routing Less Than Optimal Diverse Routing

1-5

1-6

1-7 1-11 1-12 1-13 1-17 1-19 1-26

3-5

3-6

3-7

3-8

4-5

5-2

5-5

5-7

5-8

5-9 5-12 5-15 5-16 5-17 5-17 5-19 5-20 5-21 5-22 5-23 5-24

CONTENTS

xiii

Figure 5-17. Figure 5-18. Figure 5-19. Figure 5-20.

Figure 6-1. Figure 6-2. Figure 7-1.

Figure 7-2. Figure 7-3.

Figure 7-4.

Figure 7-5. Figure 7-6. Figure 7-7.

Figure 7-8.

Excessive Cascading Minimized Cascading

Excessive Synchronization from One Node

Minimized Synchronization from One Node Physical and Virtual Carrier Slot Relationships, Line-Only Mode Physical and Virtual Carrier Slot Relationships, Line+Trunk Mode Procedure 275 Word 4:

System COS and Miscellaneous Service Assignments

(System 85 R2V4) Procedure 276 Word 1: Procedure 250 Word 1:

Feature Group COS (System 85 R2V4) System Configuration, Carriers (System 85

R2V4) Procedure 260 Word 1:

System Configuration, Circuit Pack Assignments

(System 85 R2V4) Procedure 262 Word 1: Procedure 354 Word 3: Procedure 000 Word 4:

ISDN Board Parameters NPA–NXX Assignment (System 85 R2V4) NPA–NXX/Partition Assignment (System 85

R2V4) Procedure 210 Word 2:

Attendant Partition Assignments (System 85

R2V4)

5-25 5-25 5-26 5-27

6-8

6-9

7-3 7-4

7-5

7-7 7-16 7-19

7-20

7-21

Figure 7-9.

Figure 7-10. Figure 7-11.

Figure 7-12.

Figure 7-13.

Figure 7-14.

Figure 7-15.

Figure 7-16.

Figure 7-17. Figure 7-18. Figure 7-19.

Procedure 010 Word 4:

Terminal COS Restrictions (System 85

R2V4) Procedure 100 Word 1: Procedure 100 Word 2:

Trunk Group Translations (System 85 R2V4) Trunk Group Data Characteristics (System 85

R2V4)

Procedure 100 Word 3: Translations (System 85

Procedure 101 Word 1:

Trunk Group/Trunk Type — Signaling Type R2V4)

Additional Trunk Group Translations (System 85

R2V4) Procedure 103 Word 1:

Network Trunk Group Translations (System 85

R2V4) Procedure 116 Word 1:

DS1 Trunk Assignments to Equipment/Circuit

Location (System 85 R2V4) Procedure 012 Word 1:

Name Database Establish Key (System 85

R2V4) Procedure 012 Word 2: Procedure 012 Word 3: Procedure 309 Word 1:

Name Database Entry (System 85 R2V4) Name Database (System 85 R2V4) ARS (System 85 R2V4)

7-22 7-24

7-27

7-28

7-31

7-34

7-36

7-39 7-41 7-42 7-43

xiv

CONTENTS

Figure 7-20.

Figure 7-21. Figure 7-22.

Figure 7-23.

Figure 7-24.

Figure 7-25.

Figure 7-26. Figure 7-27. Figure 7-28.

Figure 7-29.

Figure 7-30. Figure 7-31.

Procedure 309 Word 5: ARS and Transit Network Identifiers (System 85 R2V4)

Procedure 321 Word 1: AAR (System 85 R2V4) Procedure 321 Word 5: AAR and Transit Network Identifiers (System 85

R2V4) Procedure 107 Word 1: ATMS Terminating Test Line Assignment (System

85 R2V4) Procedure 108 Word 1: ISDN Terminating Test Line Assignments (System 85

R2V4) Procedure 275 Word 4: System COS and Miscellaneous Service Assignments

(Generic 2) Procedure 276 Word 1: Feature Group COS (Generic 2) Procedure 250 Word 1: System Configuration — Carriers (Generic 2) Procedure 260 Word 1: Additional DMI-MOS/ISDN-PRI Circuit Pack

Assignments (Generic 2) Procedure 262 Word 1: Additional DMI-MOS/ISDN-PRI Facility Options

(Generic 2) Procedure 262 Word 2: ISDN-PRI D-Channel Backup (Generic 2) Procedure 262 Word 3: ISDN-PRI Codeset Map Assignments (Generic

7-44 7-46

7-47

7-49

7-50

7-51 7-52 7-53

7-55

7-65 7-68

7-69

Figure 7-32.

Figure 7-33. Figure 7-34. Figure 7-35.

Figure 7-36. Figure 7-37. Figure 7-38. Figure 7-39.

Figure 7-40. Figure 7-41.

Figure 7-42.

Figure 7-43.

Procedure 280 Word 1: ISDN-PRI Receive/Transmit Codeset Mapping (Generic 2)

Procedure 354 Word 3: NPA-NXX Digits Assignment (Generic 2) Procedure 000 Word 4: NPA-NXX Index Designator Procedure 210 Word 2: LDN, NPA, and NNX Attendant Partition

Assignments Procedure 014 Word 1: BCCOS Routing Options Procedure 014 Word 2: BCCOS Data Options Procedure 010 Word 4: Terminal COS Restrictions (Generic 2) Procedure 100 Word 1: Trunk Group Type Signaling and Dial Access (ID)

Code (Generic 2) Procedure 100 Word 2: Trunk Group Data Translations (Generic 2) Procedure 100 Word 3: ISDN Trunk Group Signaling Options (Generic

2) Procedure 101 Word 1: ISDN Trunk Group, CDR, and Digital Loss Plan

(Generic 2) Procedure 103 Word 1: Network Trunk Group Translations (Generic

7-71 7-73 7-74

7-75 7-77 7-79 7-80

7-82 7-85

7-86

7-89

7-91

CONTENTS xv

Figure 7-44.

Figure 7-45. Figure 7-46. Figure 7-47. Figure 7-48. Figure 7-49. Figure 7-50. Figure 7-51.

Figure 7-52.

Figure 7-53. Figure 7-54.

Figure 7-55.

Figure 7-56. Figure 7-57. Figure 7-58. Figure 7-59. Figure 7-60. Figure 7-61. Figure 7-62. Figure 7-63.

Figure 7-64. Figure 7-65. Figure 7-66. Figure 7-67. Figure 7-68. Figure 7-69. Figure 7-70.

Figure 7-71. Figure 7-72. Figure 7-73. Figure 7-74. Figure 7-75.

Procedure 116 Word 1: DS1/DMI/ISDN-PRI Trunk Assignments (Generic

2) Procedure 012 Word 1: Name Database (Generic 2) Procedure 012 Word 2: Name Database (Generic 2) Procedure 012 Word 3: Name Database (Generic 2) Procedure 279 Word 1: Network Facilities Coding (Generic 2) Procedure 309 Word 1: ARS Route Tables (Generic 2) Procedure 309 Word 5: ARS-ISDN BCCOS (Generic 2) Procedure 321 Word 1: AAR Route Tables (Generic 2) Procedure 321 Word 5: AAR-ISDN and Other Feature Parameters (Generic

2) Procedure 107 Word 1: ATMS TTL Assignment (System 85 R2V4) Procedure 108 Word 1: ISDN Trunk Group TTL Assignment (Generic

2) DS1 Circuit Pack Screen Synchronization Plan Screen Trunk Group Screen, Page 1 Trunk Group Screen, Page 2 Trunk Group Screen, Page 1 (DMI) DS1 Circuit Pack Screen, Common-Channel Signaling DS1 Circuit Pack Screen, ISDN-PRI Signaling Synchronization Plan Screen Trunk Group Screen, Page 1 (Tie) Trunk Group Screen, Page 2 (Tie) Trunk Group Screen, Page 3 (Tie) Data Module Screen Processor Channel Assignment Screen Interface Links Screen Network-Facilities Screen Trunk Group Screen, Page 1 (ISDN-PRI) Trunk Group Screen, Page 2 (ISDN-PRI) Trunk Group Screen, Page 2 (ISDN-PRI) for Cases 1-8 Trunk Group Screen, Page 3 (ISDN-PRI) Trunk Group Screen, Page 4 (ISDN-PRI) Trunk Group Screen, Page 5 (ISDN-PRI)

7-92 7-94 7-96 7-97

7-98 7-100 7-101 7-103

7-104 7-105

7-106 7-107 7-111 7-112 7-113 7-114 7-116 7-116 7-120 7-121 7-123 7-123 7-125 7-126 7-127 7-129 7-130 7-133 7-139 7-140 7-142 7-143

xvi

CONTENTS

Figure 7-76. Figure 7-77. Figure 7-78. Figure 7-79. Figure 7-80.

Figure 8-1. Figure A-1. Figure A-2. Figure A-3. Figure A-4.

Figure A-5. Figure A-6.

Figure B-1. Figure B-2. Figure B-3. Figure B-4. Figure B-5.

SID Prefix Table Screen SID Prefix Table Screen, Sample Application Routing Patterns Screen Hunt Group Screen Terminating Extension Group Screen Facilities Generating the RFA

DS1 Circuit Pack Screen Trunk Group Screen, Page 1 (MEGACOM) Trunk Group Screen, Page 1 (MEGACOM 800) Trunk Group Screen, Page 1 (MEGACOM 800 DNIS) Trunk Group Screen, Page 1 (SDN) Synchronization Plan Screen Incorrect Translations (Procedure 260) Correct Translations (Procedure 260) Incorrect Assignment of Trunks Correct Assignment of Trunks System 75 or System 85 with CDMs

7-144 7-146 7-147 7-150 7-151

8-9 A-1 A-2 A-3 A-4 A-5 A-5 B-2 B-3 B-4 B-4 B-5

Figure B-6. Figure B-7. Figure B-8.

Figure B-9. Figure B-10. Figure B-11. Figure B-12. Figure B-13. Figure B-14. Figure B-15.

Translation Effects on the CEM Arrangement for a Complex CEM Installation System 75/System 85 to a D4-Channel Bank Internal Timing (No Synchronization) Leavenworth Loop on the Primary Reference Leavenworth Loop on the Secondary Reference No Synchronization Reference Assigned at Location A No, Primary, or Secondary Sync Reference Assigned at Location A Compatible Synchronization References Synchronization from DACS Node

B-6 B-7 B-8

B-9 B-10 B-10 B-11 B-11 B-12 B-13

LIST OF TABLES

CONTENTS

xvii

TABLE 1-1. TABLE 1-2. TABLE 1-3. TABLE 3-1. TABLE 4-1. TABLE 4-2. TABLE 5-1.

TABLE 6-1. TABLE 7-1. TABLE 7-2. TABLE 7-3.

TABLE 7-4. TABLE 7-5. TABLE 7-6. TABLE 7-7.

TABLE 7-8. TABLE 7-9.

24th-Channel Signaling Arrangement Data-Module Capabilities BCCOS System 85 Traditional Module Equalizer Settings (Metallic Cable) Digital Loss Plan Encodes Digital Loss Plan (Port-to-Port Losses) SCS References Switches Supported Digital Facilities DS1 Administration — Channel Versus Line Assignments Trunks Supporting Signaling Type 20 DS1/ISDN-PRI Administration — Channel Versus Trunk

Assignments Network Service/Feature Options Administration Summary Equipment Parameters and Permitted Translation Encodes TN767 Compensation Values Codeset Differences Trunks Supporting Signaling Type 20

1-15 1-21 1-25

3-9 4-3 4-5

5-10

6-2 7-14 7-25

7-37 7-45

7-48

7-56 7-64 7-72

7-83

TABLE 7-10.

TABLE 7-11. TABLE 7-12. TABLE 7-13.

TABLE 8-1. TABLE B-1. TABLE B-2.

TABLE B-3. TABLE B-4.

TABLE C-1. TABLE C-2.

DS1/ISDN-PRI Administration — Channel Versus Trunk Assignments

Network Services/Network Features Line Compensation Settings Line Compensation Values Minor/Major Alarm to Errored Seconds Conversions 50-Pin (25-Pair) Connector Configurations System 75 Versus System 85 Cable Comparisons 15-Pin Connector Arrangement (System 75/85 Perspective) 8-Position Modular Jack Pin Assignments (System 75 and System 85

Perspective) Internal Definition Translations System 85 R2V4 to Generic 2 IE Opcode Translations

7-93 7-99

7-108 7-117

8-10 B-14 B-15 B-16

B-17 C-10 C-12

xviii

CONTENTS

TABLE C-3. TABLE C-4. TABLE D-1. TABLE D-2.

TABLE D-3. TABLE D-4.

User-to-User IE Opcodes Codeset Map Number to Incoming and Outgoing Translations Trunk/Signaling Cross References R2V4 Alternate Signaling Type Translations Signaling Type Compatibility Signaling Type Definitions

C-12 C-12

D-2 D-6 D-7 D-8

ABOUT THIS DOCUMENT

PURPOSE

Over the past several years, basic digital signal level 1 (DS1) service has evolved to include new capabilities and thereby support more sophisticated applications. The three prime applications are:

Digital multiplexed interface with bit-oriented signaling (DMI-BOS)

Digital multiplexed interface with message-oriented signaling (DMI-MOS)

Integrated Services Digital Network primary rate interface (ISDN-PRI)

Since these three applications merely build on each proceeding application, and extend basic DS1 service, they are covered in a single document. This document is reissued (as issue 4) to:

Include coverage for the 551V ST network channel-terminating equipment (NCTE) (also called the channel service unit or CSU)

Upgrade System 85 R2V4 administration procedures to include:

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Coverage for issue 7 of the maintenance and administration panel (MAAP) flip charts Additions and corrections to the administration procedures

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Clarifications on the use of trunk type 120 (ISDN-dynamic) and other trunk types for providing Call-by-Call (CBC) Service Selection

Add coverage for DEFINITY

Add coverage for System 75XE DS1/DMI

Communications System Generic 2 ISDN-PRI

Add coverage for DEFINITY Communications System Generic 1 ISDN-PRI

This document describes System 75 and System 75XE DS1/DMIs as well as Generic 1 and Generic 2 ISDN-PRI. It introduces and defines the concepts and terminology that are unique to DS1/DMI/ISDN-PRI. Also included are descriptions of DS1/DMI/ISDN-PRI applications (for both private and public networks), engineering procedures and considerations, cabling and connection

arrangements, and administration requirements, restrictions, and limitations.

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ABOUT THIS DOCUMENT

INTENDED AUDIENCES

Since this document contains information ranging from the brief tutorial to the detailed requirements, it should prove useful to several groups of readers, including:

●

Marketing personnel

●

Technical consultants

●

Network engineers

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Installation personnel

●

System administrators

●

Account teams

●

Customers

PREREQUISITE SKILLS AND KNOWLEDGE

While there are no prerequisite skills assumed in this document, a basic understanding of telephony and networking is required. The GLOSSARY and ABBREVIATIONS appendixes of this document are provided to assist you in understanding the terminology used herein. See the Related Sources heading later in this preface, About This Document, for a list of other documents that discuss similar topics.

HOW THIS DOCUMENT IS ORGANIZED

This document consists of the following chapters:

INTRODUCTION — Provides a high-level functional description of the DS1/DMI/ISDN-PRI

1. channels, available framing formats, signaling options, and line coding formats.

NETWORK CONNECTIONS AND CONFIGURATIONS — Describes functional connection

2. arrangements to private network facilities (private endpoints) and to public network facilities (public endpoints). Included along with the public network discussions are Switched Access connections and services. This section also describes connection arrangements using digital multiplexer transmission equipment.

DS1 — TRANSMISSION AND CABLING — Describes cable distance limitations versus

3. cable size, permitted cable types, the DSX-1 interface specification, the need and function of customer service units, on- and off-premises cable configurations, metallic and nonmetallic cable options, and equalizer and compensation settings.

THE DIGITAL LOSS PLAN — Describes transmission loss concepts, the analog and digital

loss plans and the differences between them, and the user or installer impact (switch settings

and administration values). SYNCHRONIZATION OF DIGITAL FACILITIES — Describes synchronization strategies,

5. objectives, and requirements. This chapter also discusses the availability of synchronization

sources and includes the rules for selecting and assigning primary and secondary references and facilities.

ABOUT THIS DOCUMENT

PORT TYPES/INSTALLATION COMPATIBILITIES — Describes the DS1/DMI circuit pack operating modes, slot restrictions, and administration considerations and restrictions. This section also includes a table that lists the available port types and shows their compatibility on a system, release, version, and circuit-pack suffix basis.

7. ADMINISTRATION OPTIONS AND REQUIREMENTS — Covers the following information:

—

Describes those procedures that are required for DS1 services, what the available field encode options are, and the considerations for choosing the options for System 85

—

Describes those procedures that are required for DS1 services, what the available field encode options are, and the considerations for choosing the options for DEFINITY Generic 2

—

Describes the administration screens that are required for DS1 services, any unusual or special field requirements or considerations, and options for System 75 and System 75XE

—

Describes the administration screens that are required for DS1 services, any unusual or special field requirements or considerations, and options for Generic 1

8. MAINTENANCE AND ALARMS — Describes the diagnostic capabilities and alarms provided by DS1/DMI/ISDN-PRI. This part also provides information on methods of alarm analysis and alarm resolution.

●

APPENDIXES

xxi

ADMINISTRATION REQUIREMENTS — Provides screens showing administration field

examples for System 75 (RlV2 and R1V3) special-access connections. SAMPLE INSTALLATION AND MAINTENANCE PROBLEMS — Describes, with

examples, some of the more typical field problems, such as translation-based, synchronization-related, and physical-interface connection problems.

ADMINISTRATIVE PROCEDURE SUMMARY — Describes the administrative

procedures used on DEFINITY Generic 2 that relate to the ISDN-PRI, including how pertinent administrative fields relate to ISDN-PRI level 3 message contents and general

feature operation. TRUNK TYPE AND SIGNALING TYPE COMPATIBILITY TABLES — Provides

tables that define trunk type to signaling type compatibility for System 85 R2V1, R2V2, R2V3, R2V4, and Generic 2.

ABBREVIATIONS

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GLOSSARY

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INDEX

NOTE: Although this document applies specifically to DS1/DMI and to ISDN-PRI, the Generic 2 Remote Group Interface (RGI) is also a DS1 application. As such, portions of chapter 1, Introduction, chapter 3, DS1 Transmission and Cabling, chapter 4, The Digital Loss Plan, and chapter 8, Maintenance and Alarms, may also apply in a general sense to the RGI. Specific information on the RGI is provided in documents on that subject.

xxii

ABOUT THIS DOCUMENT

HOW TO USE THIS DOCUMENT

How you will use this document will depend on several factors such as the amount of training you have received or your personal preferences for working with something new. You may want to read this document from cover to cover, use it merely as a reference when questions arise, or find that something in between these two extremes will best suit your needs. At the very least, you should

make sure that you are familiar with how the document is organized and what it contains. This can be accomplished by reading this preface, About this Document, and then carefully scanning the document, taking special note of all headings.

The Table of Contents and the Index are provided for those times when you have problems finding

information about a specific topic.

TRADEMARKS AND SERVICE MARKS

●

5ESS, ACCUNET, DATAPHONE, DEFINITY, DIMENSION, MEGACOM, and UNIX are registered trademarks of AT&T.

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ESS is a trademark of AT&T.

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IBM is a registered trademark of International Business Machines Corporation.

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MS-DOS is a registered trademark of Microsoft Corporation.

RELATED SOURCES

The following documents may be referenced to obtain additional information on specific subjects.

DP2 Channel Service Unit User’s Manual AT&T DEFINITY 75/85 Communications System Generic 1 Maintenance AT&T DEFINITY 75/85 Communications System Generic 1 and System 75 and System

999-100-189 555-204-105 555-200-201

75 XE Feature Description AT&T DEFINITY 75/85 Communications System Generic 2 Administration Procedures AT&T DEFINITY 75/85 Communications System Generic 2 Maintenance Procedures AT&T DEFINITY 75/85 Communications System Generic 2 Maintenance Repair

555-104-506 555-104-117 555-104-118

Strategies AT&T Network and Data Services Reference Manual AT&T System 85 Release 2 Version 4 Administration Procedures BCM32000 — Description, Installation, and Maintenance — Digital Transmission

555-025-201 555-103-506 365-287-100

Systems

ABOUT THIS DOCUMENT

xxiii

Channel Division Multiplexer Installation and Maintenance Manual

Channel Expansion Multiplexer Installation and Maintenance Manual D4-Channel Bank Channel Units — Application Engineering DEFINITY Communications System Generic 1.1 to 4ESS Via ISDN PRI Access

DEFINITY Communications System Generic 2 Administration Procedures DEFINITY Communications System Generic 2 Maintenance Repair Strategies DEFINITY Communications System Generic 2.1 to 4ESS Via ISDN PRI Access Digital Multiplexed Interface (DMI) Technical Specification Issue 3.2 ESF T1 Channel Service Unit User Manual ISDN-BRI Reference Manual Performance Quality Analysis System 85 R2V4 to 4ESS Via ISDN PRI Access System 85 R2V4 to DEFINITY Communications System Generic 1.1 via ISDN PRI

Access

365-165-101IS 365-160-101IS 855-351-105 555-037-234 555-104-506 555-104-118 555-037-237 555-025-204 999-100-305 555-025-102 190-404-120 555-037-232

555-037-233

HOW TO MAKE COMMENTS ABOUT THIS DOCUMENT

Reader comment cards are behind the table of contents of this document. While we have tried to make this document fit your needs, we are interested in your suggestions for improving it and urge you to complete and return a reader comment card.

If the reader comment cards have been removed from this document, please send your comments to:

AT&T Technical Publications Department Room 31c32 11900 North Pecos Street Denver, Colorado 80234

xxiv

ABOUT THIS DOCUMENT

1. INTRODUCTION

Digital signal level 1 (DS1) trunks (trunks that carry 24 multiplexed channels on a single 1.544M-bps

stream and use a bit-oriented signaling (BOS) interface) were introduced in 1962 to replace older analog transmission equipment used between toll offices. At the same time, D-type channel banks (channel banks that convert analog data to digital data or vice versa) were also introduced. One

D-type channel bank (D4) is used at both the send and receive ends of a DS1 facility. At the send

end, a D4-channel bank does analog-to-digital conversions on 24 analog channels (trunks) and

multiplexes these channels to the DS1 format. At the recieve end, a D4-channel bank does an inverse operation.

Since System 75, System 85, and DEFINITY

digital switches, the analog-to-digital-to-analog conversions used in D4-channel banks are unnecessary. So in place of this DS1/D4 arrangement, digital switches can use a DS1 and a digital

multiplexed interface or DMI (an interface that multiplexes voice or data onto 23-bearer channels and

either data or signaling onto a twenty-fourth channel). The DS1/DMI arrangement does the same functions as a DS1/D4 arrangement. The signal remains digital and unaltered all the way to the

receive end. At the receive end, appropriate loss is added according to the digital loss plan if the

signal is converted back to analog. Further discussion on the subject of loss adjustments is contained in chapter 4, The Digital Loss Plan.

Some of the reasons for the recent exponential growth in the use of digital transmission facilities on

customer premises are:

Communications System Generic 1 and Generic 2 are

Advances in integrated circuit (IC) technology that permit DS1/DMI circuitry to be placed on one

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circuit pack

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Merging of mature digital carrier capabilities with those of new digital PBX capabilities in the move toward an all-digital network

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Growth of customer-premises switch size to a level comparable to that of a central office (CO)

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Congestion of trunking facilities

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High costs associated with analog copper tip-and-ring facilities

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Acceptance of and movement to the Integrated Services Digital Network (ISDN)

For these and other reasons, DS1/DMIs are revolutionizing private branch exchange (PBX) facility

interfaces by reducing their costs, increasing their function, and permitting new applications.

FUNDAMENTALS OF DS1 SIGNALS

The DS1 protocol is the lowest level for multiplexing digital voice and digital data signals. This

protocol consists of 24 64K-bps channels (each known as a DS0 channel or a digroup) plus framing bits. The 24 DS0 channels and framing bits are multiplexed together to form a 1.544M-bps signal.

1-1

1-2

INTRODUCTION

The bit stream of the DS1 protocol (1s and 0s) is transported over a DS1 line in a special way. The

1s are represented as alternating positive and negative pulses (called an alternate mark inversion (AMI) or bipolar signal); the 0s are represented as the absence of pulses. Two formats known as a DS1 line-coding formats can be used for encoding 1s into the bipolar bit stream. The DS1 channels, signaling, framing, and line-coding formats are all described in this section.

Two applications of DS1 service, known as DMI with bit-oriented signaling (DMI-BOS) and DMI with message-oriented signaling (DMI-MOS), are actually two different types of DMI interfaces. The term DMI-BOS is used when a DS1/DMI is optioned to provide BOS and when the interface is used to transport:

Data modes 0, 1, and 2 of 64K-bps digital data between the switch and a BOS-compatible computer (also mode 3 if calls are circuit switched)

Both 64K-bps data and voice between two customer-premises switches

Both 64K-bps data and voice between customer-premises switches and the public network

The term DMI-MOS is used when a DS1/DMI is optioned to provide message-oriented signaling and when the interface is used to transport:

64K-bps digital data (modes 0 through 3) between the switch and a MOS-compatible computer over private network facilities

64K-bps digital data between two customer-premises switches

Both DMI-BOS and DMI-MOS have the same channel structure, framing formats, and line-coding considerations, as well as metallic-cable considerations. Two significant differences between DMIBOS and DMI-MOS are:

a. The way signaling information is encoded into the 24th channel b. DMI-MOS bearer channels can transmit link-access procedure on the D-channel (LAPD) data

(mode 3)

NOTE: The DMI-BOS and DMI-MOS are two separate, incompatible DS1 interfaces. Communication between the two is permitted by the switch interworking functions, which are described later.

A DMI uses 24 channels in a 23B + 1D arrangement. This means that a DMI uses 23 channels to carry either voice or data (called the bearer or "B" channels) and one channel to carry either data or signaling (called the data or “D” channel). The DMI is also the forerunner of the ISDN-PRI. The term ISDN-PRI, when used alone, refers exclusively to ISDN-PRI features or capabilities.

Over the past few years, ISDN has emerged as a powerful driving force in the evolution of business communication products and services. The increased demand for products that contain internationally sanctioned (CCITT) standard interfaces exists because of:

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Widespread confusion in the market place about multiple vendor/multiple proprietary interfaces

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Growing customer dissatisfaction with proprietary equipment interfaces

INTRODUCTION

1-3

The term ISDN refers to the collection of international recommendations that are evolving toward adoption as a CCITT telecommunications standard. These recommendations are based on the following objectives:

To provide the user with end-to-end digital connectivity (which in theory will be independent of

1. the network provider)

To use the end-to-end digital connections as shared (integrated) facilities, thus permitting the

2. same channel to be used alternately for voice, data, or imagery/video

To permit users access to these new services by a limited set of multipurpose customer

3. interfaces (each interface being CCITT approved)

The long-range goal is to provide the full set of ISDN services and features on digital customerpremises switches, digital COs, and to provide these services end-to-end through the public digital network.

The CCITT ISDN recommendations define two (functionally different) types of communication interfaces. They are known as the ISDN primary rate interface (ISDN-PRI) and the ISDN basic rate interface (ISDN-BRI). ISDN-PRI recommendations (like DS1) are associated with trunk access, while ISDN-BRI recommendations are associated with line (or user terminal) access.

Initially, the CCITT recommendations were identified by their standardization committee as the “I” series documents (I.412, I.431, I.441, and I.451). Later, another CCITT development committee used the I-series documents to develop another series of documents called the "Q" series (Q.921 or Q.931). Recommendations are designed to be compatible with the Open Systems Interconnection (OSI) 7-layer model. Both ISDN-PRI and ISDN-BRI include recommendations for layers 1, 2, and

3. Recommendations for the PRI are similar in function but not identical to those for the BRI. The BRI and the PRI are compared as follows.

Layer 1 PRI defines functions provided by the physical layer. It requires use of a DS1

and is based on recommendations I.211, I.412, and I.431. These layer 1 functions include the physical connector, the creation of the bit stream by multiplexing the information B-channels and signaling D-channel, the orderly sharing of the D-channel, timing, synchronization, framing, and line coding.

Layer 2

PRI defines the signaling-channel (data-link) protocol. This layer includes the LAPD protocol (the focus of the Q.921 recommendations). The LAPD protocol permits many logical links to be multiplexed into one D-channel. It also provides flow control and error recovery for each logical link.

Layer 3

PRI defines the network-layer protocol, which consists of the Q.931 recommendations. It provides the methods (messages) to establish, maintain, and terminate network connections between communicating ISDN applications. The message set includes over 200 messages, which provide many services/features that are not available without ISDN. Some of these include:

Call establishment messages (alerting, call proceeding, connect, setup)

●

Call information phase messages (resume, suspend)

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Call disestablishment messages (disconnect, release)

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Miscellaneous messages

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1-4

INTRODUCTION

The BRI terminates at a subscriber’s residence or office. There, it connects either to an ISDN compatible terminal or to a conventional terminal via a terminal adapter. The BRI channel structure consists of a 2B + 1D format. Each B or bearer channel provides a 64K-bps information channel. Each D-channel provides a 16K-bps signaling channel.

NOTE: Specific descriptions for BRI layers 1, 2, and 3 are not included here. Another document that fully describes ISDN-BRI architecture, specific administration requirements, and service provisioning is being developed. (Refer to ISDN-BRI Reference Manual (555-025-102) for more information.)

When connecting customer-premises switches to the public network, consider the features and services supported on each end of the connection. At the time of this publication, the AT&T public network supported the following services:

● Switched digital service

● MEGACOM

● MEGACOM 800

●

Call-by-call (CBC) Service Selection

● Automatic number identification (ANI)

System 85 R2V4 supports ISDN-PRI but not ISDN-BRI. However, System 85 R2V4 uses the lineside digital communications protocol (DCP) to provide end-to-end digital connectivity. The DCP channel structure consists of 2I + 1S channel format. Each I-channel provides a 64K-bps information (voice/data) channel, while the S-channel provides an 8K-bps signaling channel. The DCP is similar to ISDN-BRI, both in structure and in function. The DCP was AT&T’s early attempt to offer (what at that time was) the evolving BRI standard. Figure 1-1, System 85 R2V4 ISDN Configuration, shows various trunk-side and line-side connections to a System 85 R2V4.

INTRODUCTION

1-5

Figure 1-1. System 85 R2V4 ISDN Configuration

Generic 2 provides a signaling method called nonfacility-associated signaling (NFAS). NFAS allows a D-channel on one PRI facility (sometimes called a PRI pipe) to provide signaling for B-channels on another PRI pipe. With NFAS, if two or more PRI pipes are present, an optional D-channel backup feature is available. One D-channel is administered as the primary D-channel on one DS1 and the secondary D-channel on another DS1. Only one D-channel per primary-secondary pair can be active at a time. If the primary D-channel fails, the signaling function is switched automatically to the secondary (sometimes called the backup) D-channel. Without D-channel backup, D-channel failure

results in loss of service for all calls passing through a PRI pipe.

Generic 2 offers ISDN-BRI, however, some BRI capabilities are not initially available. Figure 1-2, Generic 2 ISDN Network Configuration, shows a Generic 2 switch in a sample network.

1-6

INTRODUCTION

Figure 1-2. Generic 2 ISDN Network Configuration

Generic 1 and Generic 2 provide ISDN-PRI but do not support wideband channels. Additionally, ISDN-BRI is not currently supported in Generic 1. However, end-to-end digital connections are permitted via line-side DCP-interface voice terminals and DCP-interface data modules. Figure 1-3, Generic 1 ISDN Network Configuration, shows a Generic 1 in a sample network.

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