Paradyne COMSPHERE 3920PLUS Series User manual

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Paradyne product document.
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AT&T. Any reference to AT&T Paradyne is
amended to read Paradyne Corporation.

April 1995
COMSPHERE
392x
Plus Modems
Models 3920
Plus and 3921 Plus
Installation and Operation Manual
Document No. 3920-A2-GN31-10
P a
r
a dyn e
Printed on recycled paper

COMSPHERE 392xPlus Modems
AApril 1995 3920-A2-GN31-10
COMSPHERE
392x
Plus Modems
Models 3920
Plus and 3921 Plus
Installation and Operation Manual
3920-A2-GN31-10
2nd Edition (April 1995)
Changes and enhancements to the product and to the information herein will be documented and issued as a new release or
a Firmware Update Description document to this manual.
A customer opinion card is provided at the front of this publication and your comments are appreciated. If the form has
been removed, address comments to AT&T Paradyne Corporation, Technical Publications, 8545 126th Ave. N., P.O. Box
2826, Largo, Florida 34649-2826. AT&T Paradyne may use or distribute any of the information supplied, as appropriate,
without incurring any obligation whatsoever.
For the 3920Plus standalone modems, the Universal Service Order Code (USOC) for Permissive mode is RJ11C. The
Canadian equivalent to RJ11C is CA11A. For 392xPlus carrier-mounted modems, the USOC for Permissive mode is
RJ21X. The Canadian equivalent to RJ21X is CA21A.
For regulatory approval, refer to the product labeling or contact your local AT&T Paradyne representative.
COMSPHERE is a registered trademark of AT&T.
DATAKIT is a registered trademark of AT&T.
IBM is a registered trademark of International Business Machines Corporation.
Microcom Networking Protocol is a registered trademark of Microcom, Inc.
Sun Workstation is a registered trademark of Sun Microsystems, Inc.
UNIX is a registered trademark of Novell in the United States and other countries, licensed exclusively through X/Open Limited.
COPYRIGHT E 1995 AT&T Paradyne Corporation. All rights reserved.
Thispublicationisprotectedby federalcopyrightlaw.No partofthispublication maybecopiedor distributed,transmitted,transcribed,stored inaretrievalsystem,
ortranslatedintoanyhumanorcomputerlanguageinanyformorbyanymeans,electronic,mechanical,magnetic,manualorotherwise,ordisclosedtothirdparties
without the express written permission of AT&T Paradyne Corporation, 8545 126th Avenue North, P.O. Box 2826, Largo, Florida 34649-2826.
AT&T Paradyne Corporation makes no representation or warranties with respect to the contents hereof and specifically disclaims any implied warranties of
merchantability or fitness for a particular purpose. Further, AT&T Paradyne Corporation reserves the right to revise this publication and to make changes from
time to time in the contents hereof without obligation of AT&T Paradyne Corporation to notify any person of such revision or changes.

Safety Instructions
B3920-A2-GN31-10 April 1995
Important Safety Instructions
1. Read and follow all warning notices and instructions marked on the product or
included in the manual.
2. This product is intended to be used with a three-wire grounding type plug – a plug
which has a grounding pin. This is a safety feature. Equipment grounding is vital to
ensure safe operation. Do not defeat the purpose of the grounding type plug by
modifying the plug or using an adaptor.
Prior to installation, use an outlet tester or a voltmeter to check the ac receptacle for
the presence of earth ground. If the receptacle is not properly grounded, the
installation must not continue until a qualified electrician has corrected the problem.
If a three-wire grounding type power source is not available, consult a qualified
electrician to determine another method of grounding the equipment.
3. Slots and openings in the cabinet are provided for ventilation. To ensure reliable
operation of the product and to protect it from overheating, these slots and openings
must not be blocked or covered.
4. Do not allow anything to rest on the power cord and do not locate the product where
persons will walk on the power cord.
5. Do not attempt to service this product yourself, as opening or removing covers may
expose you to dangerous high voltage points or other risks. Refer all servicing to
qualified service personnel.
6. General purpose cables are provided with this product. Special cables, which may be
required by the regulatory inspection authority for the installation site, are the
responsibility of the customer.
7. When installed in the final configuration, the product must comply with the applicable
Safety Standards and regulatory requirements of the country in which it is installed. If
necessary, consult with the appropriate regulatory agencies and inspection
authorities to ensure compliance.
8. A rare phenomenon can create a voltage potential between the earth grounds of two
or more buildings. If products installed in separate buildings are interconnected, the
voltage potential may cause a hazardous condition. Consult a qualified electrical
consultant to determine whether or not this phenomenon exists and, if necessary,
implement corrective action prior to interconnecting the products.
In addition, if the equipment is to be used with telecommunications circuits, take the
following precautions:
– Never install telephone wiring during a lightning storm.
– Never install telephone jacks in wet locations unless the jack is specifically designed
for wet locations.
– Never touch uninsulated telephone wires or terminals unless the telephone line has
been disconnected at the network interface.
– Use caution when installing or modifying telephone lines.
– Avoid using a telephone (other than a cordless type) during an electrical storm.
There may be a remote risk of electric shock from lightning.
– Do not use the telephone to report a gas leak in the vicinity of the leak.

COMSPHERE 392xPlus Modems
CApril 1995 3920-A2-GN31-10
Notices
                 
              
           
             
            
              
              
  
            
             
    


      
               
            

 "  " "    " "  
   "        !  
 " ""   !    

i3920-A2-GN31-10 April 1995
Table of Contents
Preface
Objectives and Reader Assumptions vii. . . . . . . . . . . . . . . . . . . . . . . . . . .
How to Use This Manual vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related Documents viii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ordering Information viii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. Introduction
Overview 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Multipoint Applications 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual-Leased Backup Applications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
MSD Application 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Bridge Application 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMSPHERE 392xPlus Models 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Government Requirements and Equipment Return 1-6. . . . . . . . . . . . . . . .
Equipment Warranty and Support 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Specifications 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Modem Installation
Overview 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
392xPlus Modem Package 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model 3920Plus Modem Installation 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTE Connection 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model 3920Plus 4-Wire/2-Wire Leased-Line Network Connection 2-4. . .
Dial Network Connection 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model 3920Plus Dial Backup Connection 2-4. . . . . . . . . . . . . . . . . . . . . .
Model 3920Plus Leased Backup Connection 2-5. . . . . . . . . . . . . . . . . . . .
Network Management System Connection 2-5. . . . . . . . . . . . . . . . . . . . . .
Power Supply Connection 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modem Power-Up 2-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selecting Factory Configuration Options 2-6. . . . . . . . . . . . . . . . . . . . . . .
Removing and Replacing Model 3920Plus Modems 2-8. . . . . . . . . . . . . .
Model 3921Plus Modem Installation 2-8. . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing and Replacing Model 3921Plus Modems 2-11. . . . . . . . . . . . . .

COMSPHERE 392xPlus Modems
ii April 1995 3920-A2-GN31-10
3. DCP Operation
Overview 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Control Panels 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Indicators 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Control Panel Operation 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . .
Menu Structure 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Branch 3-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configure Branch 3-30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Poll List Branch 3-30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Branch 3-35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Branch 3-53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sub-Network Health and Status Branch 3-63. . . . . . . . . . . . . . . . . . . . . . . .
Call Setup Branch 3-64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Talk/Data Branch 3-72. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Security Branch (Mux Disabled) 3-74. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Branch 3-75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. DCP Configuration
Overview 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configure Branch 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Tables 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mux Enabled 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mux Disabled 4-31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. AT Command Set and S-Registers
Overview 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Modes 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Command Guidelines 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AT Command List 5-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S-Register List 5-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. Dial Access Security
Overview 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Security Branch 6-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Security Configuration Options 6-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Security Password Entry Techniques 6-15. . . . . . . . . . . . . . . . . . . . . . . . . . .
Database Table Examples 6-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
iii3920-A2-GN31-10 April 1995
Appendices
A. Menu Tree A-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B. Troubleshooting B-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C. Pin Assignments C-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D. CCITT V.25bis Dialing Commands and Response D-1. . . . . . . . . .
E. ASCII Character Table E-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F. Default Configuration Options F-1. . . . . . . . . . . . . . . . . . . . . . . . .
G. Sample Configurations G-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
H. Equipment List H-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glossary
Index

COMSPHERE 392xPlus Modems
iv April 1995 3920-A2-GN31-10
List of Figures
Figure Page
1-1 Model 3920Plus 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2 Model 3921Plus 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-1 Model 3920Plus Rear Panel and Power Supply 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-2 Installing a Model 3921Plus Modem 2-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-3 Circuit Pack Lock 2-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1 Model 3920Plus DCP 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-2 Optional SDCP and Model 3921Plus Faceplate 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-3 392xPlus LCD and Keypad 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-4 Local Analog Loopback 3-56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-5 Remote Digital Loopback 3-57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-6 Local Digital Loopback 3-59. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-7 Pattern Test and Local Analog Loopback Test 3-60. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-8 Pattern Test and Digital Loopback Test 3-61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-9 End-to-End Pattern Test 3-61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-10 Dial Backup 3-67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1 DCP Configuration Process 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-1 VF Pin Orientation C-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-2 Wiring Diagram — “Y” Cable for External Telephone C-4. . . . . . . . . . . . . . . . . . . . . . .
C-3 Wiring Diagram — 8-Position to 6-Position Crossover Cable C-5. . . . . . . . . . . . . . . . .
C-4 Wiring Diagram — 25-Position Crossover Cable C-6. . . . . . . . . . . . . . . . . . . . . . . . . . .
G-1 Sample Configuration — Point-to-Point G-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-2 Sample Configuration — Extended Point-to-Point G-4. . . . . . . . . . . . . . . . . . . . . . . . . .
G-3 Sample Configuration — Extended Multipoint G-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-4 Sample Configuration — Point-to-Point with Automatic Dial Backup G-8. . . . . . . . . .
G-5 Sample Configuration — Point-to-Point with Network Management G-10. . . . . . . . . . .
G-6 Sample Configuration — Carrier with Network Management G-12. . . . . . . . . . . . . . . . .
G-7 Sample Configuration — Extended Diagnostics G-14. . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-8 Sample Configuration — Digital Bridging G-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-9 Sample Configuration — Point-to-Point MSD G-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-10 Sample Configuration — Multipoint MSD G-20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
v3920-A2-GN31-10 April 1995
List of Tables
Table Page
1-1 Technical Specifications for 392xPlus Modems 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1 Model 3920Plus and Model 3921Plus DCP LEDs 3-5. . . . . . . . . . . . . . . . . . . . . . . . . .
3-2 SDCP LEDs 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-3 Top-Level Menu Status 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-4 Common Operational Messages 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-5 Dial Access Security Messages 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-6 Health and Status Messages 3-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-7 Backup Status Screens 3-27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-8 Valid Ranges for VF Thresholds 3-52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-9 Valid Dial Command Modifiers 3-71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1 DTE Interface Configuration Options — Mux ENABLED 4-10. . . . . . . . . . . . . . . . . . .
4-2 Line Dialer Configuration Options — Mux ENABLED 4-19. . . . . . . . . . . . . . . . . . . . . .
4-3 Dial Line Configuration Options — Mux ENABLED 4-22. . . . . . . . . . . . . . . . . . . . . . .
4-4 Leased Line Configuration Options — Mux ENABLED 4-24. . . . . . . . . . . . . . . . . . . . .
4-5 Test Configuration Options — Mux ENABLED 4-27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-6 Miscellaneous Configuration Options — Mux ENABLED 4-28. . . . . . . . . . . . . . . . . . .
4-7 DTE Interface Configuration Options — Mux DISABLED 4-32. . . . . . . . . . . . . . . . . . .
4-8 DTE Dialer Configuration Options — Mux DISABLED 4-40. . . . . . . . . . . . . . . . . . . . .
4-9 Line Dialer Configuration Options — Mux DISABLED 4-45. . . . . . . . . . . . . . . . . . . . .
4-10 Dial Line Configuration Options — Mux DISABLED 4-49. . . . . . . . . . . . . . . . . . . . . . .
4-11 Leased Line Configuration Options — Mux DISABLED 4-52. . . . . . . . . . . . . . . . . . . .
4-12 V.42/MNP/Buffer Configuration Options — Mux DISABLED 4-57. . . . . . . . . . . . . . . .
4-13 Test Configuration Options — Mux DISABLED 4-63. . . . . . . . . . . . . . . . . . . . . . . . . . .
4-14 Miscellaneous Configuration Options — Mux DISABLED 4-65. . . . . . . . . . . . . . . . . . .
5-1 Result Codes 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2 392xPlus AT Commands 5-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3 392xPlus S-Registers 5-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-1 Edit Password Table Group Options 6-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-2 Set Answer Security Group Options 6-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-3 Set Originate Security Group Options 6-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4 Security Configuration Options 6-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-5 Security Database Table Using VF-Side Passwords 6-16. . . . . . . . . . . . . . . . . . . . . . . . .
6-6 Security Database Table Using DTE-Side Passwords 6-17. . . . . . . . . . . . . . . . . . . . . . . .
6-7 Security Database Table Using Both VF-Side and DTE-Side Passwords 6-17. . . . . . . . .
B-1 Modem Health B-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-2 Leased-Line Operation B-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-3 Dial Backup Operation B-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-4 Modem — DTE Connection B-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-5 Modem — VF Connection B-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-6 Online Operation B-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COMSPHERE 392xPlus Modems
vi April 1995 3920-A2-GN31-10
Table Page
B-7 Mux Operation B-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-1 EIA-232-D Pin Assignments C-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-2 VF Connector Pin Assignments C-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-1 V.25bis Commands D-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-2 V.25bis Response Messages D-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E-1 ASCII Characters E-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F-1 Factory Default Configuration Options F-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vii3920-A2-GN31-10 April 1995
Preface
Objectives and Reader Assumptions
This manual describes how to install and operate the COMSPHERE r 3920Plus standalone and
3921Plus carrier-mounted modems. This manual assumes that you have a basic understanding of
modems and their operation.
How to Use This Manual
Chapter 1 provides technical specifications, information about the 3900Plus modems’ features, and
the government requirements for using these modems.
Chapter 2 provides instructions for installing the 3900Plus modems.
Chapter 3 provides the information required to operate the Model 3920Plus using the diagnostic
control panel and the Model 3921Plus using the COMSPHERE 3000 Series Carrier’s shared
diagnostic control panel (SDCP).
Chapter 4 provides the information required to set configuration options in the 392xPlus modems
using the modem’s diagnostic control panel.
Chapter 5 provides instructions for using AT commands and S-Registers.
Chapter 6 provides instructions for using the Dial Access Security feature.
Appendix A provides a menu tree for the 392xPlus modems.
Appendix B provides instructions for performing diagnostic tests when data communication
problems occur.
Appendix C provides EIA-232-D and VF TELCO pin assignments.
Appendix D provides V.25bis dialing information.
Appendix E provides an ASCII translation chart.
Appendix F provides a list of all default configuration options available for the factory preset
configurations.
Appendix G provides diagrams of sample configurations for the 392xPlus modems.
Appendix H provides an equipment list for the 392xPlus modems.
The Glossary provides a description of terms used throughout this manual.

COMSPHERE 392xPlus Modems
viii April 1995 3920-A2-GN31-10
Related Documents
3000-A2-GA31 COMSPHERE 3000 Series Carrier, Installation Manual
3610-A2-GZ45 3600 Hubbing Device, Feature Number 3600-F3-300, Installation
Instructions
3920-A2-GK41 COMSPHERE 392xPlus Modems, Models 3920Plus and 3921Plus,
Installation Instructions
3920-A2-GK40 COMSPHERE 3900 Series Modems, Model 3921Plus, Ferrite Choke
Installation Instructions
Ordering Information
To order AT&T Paradyne documentation, please call 1-800-545-2354, extension 2222.

1-13920-A2-GN31-10 April 1995
Introduction
Overview 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Multipoint Applications 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual-Leased Backup Applications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MSD Application 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Bridge Application 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMSPHERE 392xPlus Models 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standalone Model 3920Plus 4-Wire/2-Wire Modem 1-4. . . . . . . . . . . . . . . .
Carrier-Mounted Model 3921Plus 4-Wire/2-Wire Modem 1-5. . . . . . . . . . . .
Government Requirements and Equipment Return 1-6. . . . . . . . . . . . . . . . . . . .
United States 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment Warranty and Support 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment Service 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Out of Warranty 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enhanced Support Services 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Canada 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Specifications 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview
The COMSPHERE r 392xPlus modems include an integral time division multiplexer (TDM) with
a modem sharing device (MSD) as standard equipment. The TDM provides time division
multiplexing of up to four independent ports over point-to-point lines using the V.34 family or
V.32 family modulation. The MSD allows multiple physical ports on a tributary modem to share a
single communication channel using the V.34 family, V.32 family or TMp modulation. These
modems operate over leased-line or dial networks. The multiplexer (mux) can be enabled or
disabled to allow a greater degree of application flexibility.
The modem’s compatibility with a number of modulations and the user-friendly diagnostic control
panel (DCP) permit the 392xPlus modem to be used in a variety of applications and environments
while also allowing control over modem configuration, dialing, and diagnostics.
Features
The 392xPlus modems have a wide variety of features.
•With the mux enabled, four-port time division multiplexer (TDM) operation.
•With the mux enabled, Modem Sharing Device (MSD).
•With the mux enabled, Digital Bridging.
•Additional VF parameters under the V.32 family modulations in 4-wire mode.
1

COMSPHERE 392xPlus Modems
1-2 April 1995 3920-A2-GN31-10
•International Support to correctly detect the call progress signals (dial tone, busy, fast busy,
ringback) for a variety of countries.
•Extended data circuits with diagnostics.
•With the mux enabled, four-wire/two-wire leased-line modulations: V.34 (33,600, 28,800,
24,000, 19,200, 16,800, 14,400, 12,000, 9600, 7200, 4800, and 2400 bps), V.32 terbo
(19,200 and 16,800 bps), V.32bis (14,400, 12,000, 9600, 7200, and 4800 bps), V.32 (9600
and 4800 bps), and Trellis Multipoint (TMp) (19,200, 14,400, 9600, 7200, 4800, and
2400 bps).
•With the mux enabled, dial-line modulations: V.34 (33,600, 28,800, 24,000, 19,200, 16,800,
14,400, 12,000, 9600, 7200, 4800, and 2400 bps), V.32 terbo (19,200 and 16,800 bps),
V.32bis (14,400, 12,000, 9600, 7200, and 4800 bps), V.32 (9600 and 4800 bps).
•With the mux disabled, four-wire/two-wire leased-line modulations: V.34 (33,600, 31,200,
28,800, 26,400, 24,000, 21,600, 19,200, 16,800, 14,400, 12,000, 9600, 7200, 4800, and
2400 bps), V.32 terbo (19,200 and 16,800 bps), V.32bis (14,400, 12,000, 9600, 7200, and
4800 bps), V.32 (9600 and 4800 bps), Trellis Multipoint (19,200, 14,400, 9600, 7200, 4800,
and 2400 bps), V.22bis (2400 bps), V.27bis (4800 and 2400 bps), V.33 (14,400 and
12,000 bps), and V.29 (9600, 7200, and 4800 bps).
•With the mux disabled, dial-line modulations: V.34 (33,600, 31,200, 28,800, 26,400, 24,000,
21,600, 19,200, 16,800, 14,400, 12,000, 9600, 7200, 4800, and 2400 bps), V.32 terbo
(19,200 and 16,800 bps), V.32bis (14,400, 12,000, 9600, 7200, and 4800 bps), V.32 (9600
and 4800 bps), V.22bis (2400 bps), V.22 (1200 bps), V.23 (1200 and 600 bps), V.21
(300 bps), Bell 212A (1200 bps), and Bell 103J (300 bps).
•Channel adaptive Trellis-Coded Modulation, AT&T Paradyne’s advanced Trellis-Coded
transparent forward error correction for Trellis multipoint and high-speed point-to-point
applications.
•Convenient migration to new or optional features through software downloading.
•Extended data circuits with diagnostic capabilities.
•Network management system (NMS) support through the COMSPHERE 6800 or
6700 Series NMS using Advanced Diagnostic protocol (ADp).
•Automatic and manual backup with standby capabilities for 4-wire/2-wire leased-line
applications. (The backup facility may be either a 2-wire dial line or a 2-wire leased line.)
Multipoint Applications
In multipoint applications, leased-line circuits are used for time sharing the same front-end
processor (FEP) port with multiple remote locations. The FEP (via the control modem) regulates
traffic on the line by continuously polling the tributary DTE(s) in a predefined sequence. Only one
tributary can communicate with the control modem at a given time. Modems configured for Trellis
Multipoint (TMp) cannot be used in a point-to-point, constant carrier application. (Refer to the
Leased Line — Mux Enabled or the Leased Line — Mux Disabled section in Chapter 4 for
configuration options.)

Introduction
1-33920-A2-GN31-10 April 1995
Dual-Leased Backup Applications
In dual-leased backup applications, a 2-wire leased line is used as the backup facility instead of the
normal 2-wire dial line. Plug the leased line into the jack labeled DIAL on the rear panel of the
modem (see Figure 2-1 in Chapter 2), and enable the Dual_Leased_Ln configuration option. (Refer
to the Leased Line — Mux Enabled or the Leased Line — Mux Disabled section in Chapter 4 for
configuration options.) Except for dialing, ring indication, and call progression functions, you
control the backup function as if it were a normal dial backup.
MSD Application
The Modem Sharing Device allows from 2 to 4 physical ports to share a communication channel.
When the Mux Mode option is set to TDM/MSD on a tributary, and at least one port has the MSD
mode setting enabled, then MSD is enabled. For more information, refer to the Mux Enabled
section of Chapter 4 for configuration options or the Point-to-Point MSD and Multipoint MSD
sample configurations in Appendix G.
When MSD mode is enabled:
•The MSD Control configuration option is added at the end of the Mux Sub-Group.
•The EIA Port Sub-group includes the RTS Antistream configuration option.
Digital Bridge Application
The Digital (DTE) Bridge provides the ability for dial backup of a multipoint configuration by
bridging the signal on the digital side of the FEP end modems. In this configuration, only two ports
(both on the FEP side) are used on the control and backup modems. Data received on Port 1 is
transmitted across the communication link, as well as looped back out of Port 2. Data received
across the communication link and on Port 2 are sent out of Port 1. For more information, refer to
the Mux Enabled section of Chapter 4 or the Digital Bridging sample configuration in Appendix G
for sample configurations.
When the Digital Bridge is enabled, a new menu is present with the following conditions:
•TDM capability is disabled when DTE Bridge mode is enabled, therefore the rate of Port 1
is forced to run at the line rate.
•Configuration options are provided for Port 1 only; Port 2 cannot be configured.
•Ports 3 and 4 are not available.
•Port-related tests, such as digital loopbacks and Pattern tests, are available for Port 1.
•DTE Status, Health and Status, and LED control are available for both Ports 1 and 2.

COMSPHERE 392xPlus Modems
1-4 April 1995 3920-A2-GN31-10
COMSPHERE 392x Plus Models
The 392xPlus family is available in two models: the Model 3920Plus, a 4-wire/2-wire standalone
modem, and the Model 3921Plus, a carrier-mounted version of the standalone unit.
Standalone Model 3920 Plus 4-Wire/2-Wire Modem
The standalone Model 3920Plus modem (Figure 1-1) is capable of either 4-wire/2-wire leased-line
or dial operation. The modem is controlled using the diagnostic control panel (DCP). The DCP
consists of a liquid crystal display (LCD), three function keys, four directional keys, and a row of
13 LED status indicators. For a better understanding of DCP operation, refer to Chapter 3, DCP
Operation.
The rear panel of the modem contains an ON/OFF power switch, a low voltage dc power
connector, an 8-pin modular connector (LEASED) for leased-line connection, an 8-pin modular
connector (DIAL) for dial-line or leased-line backup, a 4-pin modular connector (NMS) for
network management, and a DB-25-S DTE connectors.
Figure 1-1. Model 3920 Plus

Introduction
1-53920-A2-GN31-10 April 1995
Carrier-Mounted Model 3921 Plus 4-Wire/2-Wire Modem
The carrier-mounted Model 3921Plus modem (Figure 1-2) installs into a COMSPHERE 3000
Series Carrier. The Model 3921Plus modem’s faceplate covers two slots in the carrier. It has
20 LED status indicators for displaying modem activity and an audio speaker jack for the carrier’s
optional speaker.
The Model 3921Plus modem’s rear panel has four edge card connectors that mount into two
connector plates. Each connector plate has two DB-25-S connectors providing four EIA-232-DTE
interfaces.
Figure 1-2. Model 3921 Plus

COMSPHERE 392xPlus Modems
1-6 April 1995 3920-A2-GN31-10
The Model 3921Plus derives ac power from the COMSPHERE 3000 Series Carrier’s backplane,
which is a common bus to all devices installed in the carrier. The user interface to any
Model 3921Plus is through the shared diagnostic control panel (SDCP), an optional feature which
operates in a manner similar to the DCP on the Model 3920Plus. For a better understanding of
DCP operation, refer to Chapter 3, DCP Operation.
The COMSPHERE 3000 Series Carrier has a total of 17 slots. The first slot, Slot 0, is reserved for
the shared diagnostic unit (SDU) while the remaining 16 slots can house up to 8 Model 3921Plus
modems, or a combination of Model 3921Plus modems and other units. For more details on the
COMSPHERE 3000 Series Carrier, refer to the COMSPHERE 3000 Series Carrier, Installation
Manual.
Government Requirements and Equipment Return
Certain governments require that instructions pertaining to modem connection to the public
switched telephone network be included in the installation and operation manual. Specific
instructions are listed in the following sections.
United States
NOTICE TO USERS OF THE PUBLIC SWITCHED TELEPHONE NETWORK
1. This equipment complies with Part 68 of the FCC rules. On the equipment is a label that
contains, among other information, the FCC registration number and ringer equivalence
number (REN) for this equipment. The label is located on the bottom of the
Model 3920Plus modem. This label is located on the Model 3921Plus modem’s circuit
card assembly. If requested, this information must be provided to the telephone company.
2. Page A of this manual contains the Universal Service Order Codes (USOC) associated with
the services on which the equipment is to be connected.
3. An FCC compliant telephone cord and modular plug is provided with this equipment. This
equipment is designed to be connected to the telephone network or premises wiring using a
compatible modular jack which is Part 68 compliant. See Installation Instructions for
details.
4. The ringer equivalence (REN) is used to determine the quantity of devices which may be
connected to the telephone line. Excessive RENs on the telephone line may result in the
devices not ringing in response to an incoming call. In most, but not all areas, the sum of
the RENs should not exceed five (5.0). To be certain of the number of devices that may be
connected to the line, as determined by the total RENs, contact the telephone company to
determine the maximum RENs for the calling area.
5. If the 392xPlus modem causes harm to the telephone network, the telephone company will
notify you in advance that temporary discontinuance of service may be required. But if
advance notice is not practical, the telephone company will notify the customer as soon as
possible. Also, you will be advised of your right to file a complaint with the FCC if you
believe it is necessary.
6. The telephone company may make changes in its facilities, equipment, operations, or
procedures that could affect the operation of the equipment. If this happens, the telephone
company will provide advance notice in order for you to make the necessary modifications
in order to maintain uninterrupted service.

Introduction
1-73920-A2-GN31-10 April 1995
7. The user is not authorized to repair or modify the equipment.
8. This equipment cannot be used on public coin service provided by the telephone company.
Connection to Party Line Service is subject to state tariffs. (Contact the state public utility
commission, public service commission or corporation commission for information.)
Equipment Warranty and Support
AT&T Paradyne’s Customer Assistance Center is available 24 hours a day to help you place an
installation request, report a hardware or software problem, or place a trouble report. The center
provides technical support and remotely diagnoses equipment problem. You can also call the center
if you participate in the on-site support program (refer to the Enhanced Support Services section)
or if you would like to request support on a time and materials basis.
Call the following toll-free number to reach the Customer Assistance Center:
1-800-237-0016
Equipment Service
To obtain service under your warranty, call the Customer Assistance Center at the number listed
above. Please have the following information available before you call:
Company Name and Address
Contact Name and Telephone Number
Shipping Address, if different from the company address
Billing Address, if different than the shipping address
Model Number and Serial Number of the unit
A brief description of the problem
The Customer Assistance Center will verify that the equipment is in need of repair. You are
provided a Return Materials Authorization (RMA) number to help expedite the repair request.
Once you receive an RMA number, pack the unit securely and ship the package insured and
postage prepaid to:
AT&T Paradyne Corporation
Customer Support
Attn: Repair Center
8550 Ulmerton Road, Building B
Largo, Florida 34641
Make sure the RMA number is in a visible location on the outside of the package.
Out of Warranty
If your equipment is out of warranty and you do not have a maintenance support agreement,
factory repair support is available.
To send equipment to AT&T Paradyne’s Repair Center, call the following toll-free number
Monday through Friday, between the hours of 8 a.m. and 5 p.m. EST, excluding holidays:
1-800-772-7691
Please have your purchase order number and the information listed in the Equipment Service
section ready when you call for your RMA number. Package and ship the equipment to the Repair
Center as described, making sure the RMA number is clearly visible on the outside of the package.