CSCO-1007
`Cisco v. TQ Delta
`Page 1 to 186
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`

`
`ANSI T].-Ll].3 ‘l5 — |J?E'-iL5D B52506‘! BEE —
`
`ANSl®
`11.413-1995
`
`American National Standard
`
`for Telecommunications —
`
`Network and Customer Installation Interfaces —
`Asymmetric Digital Subscriber Line (ADSL) Metallic Interface
`
`Secretariat
`
`Alliance for Telecommunications Industry Solutions
`
`Approved August 18, 1995
`
`American National Standards Institute, Inc.
`
`Abstract
`
`This standard presents the electrical characteristics of the Asymmetric Digital Subscriber Line
`(ADSL) signals appearing at the network interface. The physical interface between the network
`and the customer installation is also described. The transport medium for the signals is a single
`twisted-wire pair that supports both Message Telecommunications Service (POTS) and tull-duplex
`(simultaneous two—way) and simplex (from the network to the customer installation) digital ser-
`vices.
`
`This interface standard provides the minimal set of requirements for satisfactory transmission
`between the network and the customer installation. Equipment may be implemented with addition-
`at functions and procedures.
`
`Copyright American National Standards institute
`No reproduction or networking permitted without license from lHS
`Provided by IHS under license with ANSl
`
`829754
`
`'
`Order lvumber. W1
`N0‘ f°" 555 Ev
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`

`
`American
`National
`Standard
`
`ANSI T]i.ll]i3 ‘I5 — I372‘-lI|i5iJ UEEEDHD EMT —
`
`Approval of an American National Standard requires verification by ANSI that the
`requirements for due process, consensus, and other criteria for approval have
`been met by the standards developer.
`
`Consensus is established when, in the judgment of the ANSI Board of Standards
`Fteview, substantial agreement has been reached by directly and materially
`affected interests. Substantial agreement means much more than a simple
`majority, but not necessarily unanimity. Consensus requires that all views and
`objections be considered, and that a concerted effort be made toward their
`resolution.
`
`The use of American National Standards is completely voluntary; their existence
`does not
`in any respect preclude anyone, whether he has approved the
`standards or not. from manufacturing, marketing, purchasing, or using products,
`processes, or procedures not conforming to the standards.
`
`The American National Standards Institute does not develop standards and will in
`no circumstances give an interpretation of any American National Standard.
`Moreover, no person shall have the right or authority to issue an interpretation of
`an American National Standard in the name of the American National Standards
`Institute. Requests for interpretations should be addressed to the secretariat or
`sponsor whose name appears on the title page of this standard.
`
`CAUTION NOTICE: This American National Standard may be revised or
`withdrawn at any time. The procedures of the American National Standards
`Institute require that action be taken periodically to reaffirm, revise, or withdraw
`this standard. Purchasers of American National Standards may receive current
`information on all standards by calling or writing the American National Standards
`Institute.
`
`NOTE — The user's attention is called to the possibility that compliance with this standard may require use of
`an invention covered by patent rights.
`By publication of this standard, no position is taken with respect to the validity of this claim or of any patent
`rights in connection therewith. The patent holder has, however, filed a statement of willingness to grant a
`license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring
`to obtain such a license. Details may be obtained irom the publisher.
`
`Published by
`
`American National Standards Institute
`11 West 42nd Street, New York, New York 10036
`
`Copyright ©1995 by Alliance for Telecommunications Industry Solutions
`All rights reserved.
`
`No part of this publication may be reproduced in any
`form, in an electronic retrieval system or otherwise,
`without prior written permission of the publisher.
`
`Printed in the United States of America
`
`APS3C1295/135
`
`Copyright American National Standards institute
`Provided by IHS under license with ANSl
`No reproduction or networking permitted without license from lHS
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`Order Number: W1829'/E4
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`Page 3 of 186
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`

`
`ANSI Tl-‘+1.3 ‘I5 — El?E'-l]i5U lJ5Bl:aD‘i]i BEE. —
`
`Contents
`
`Page
`Foreword ........................................................................................................... ..vii
`
`Scope and purpose .............................................................................. ..1
`
`Scope ................................................................................................... ..1
`Purpose ................................................................................................ ..1
`
`Normative references ........................................................................... ..2
`
`Definitions, abbreviations, acronyms and symbols ............................... ..3
`
`Definitions ............................................................................................. ..3
`
`Abbreviations, acronyms and symbols ................................................. ..3
`
`Reference models ................................................................................ ..6
`
`System reference model ....................................................................... ..6
`ATU-C transmitter reference model ...................................................... ..7
`ATU-Ft transmitter reference model ...................................................... ..8
`
`Transport capacity ................................................................................ ..9
`
`Simplex bearers .................................................................................... ..9
`Duplex bearers ................................................................................... ..13
`Combined options............................................................................... ..14
`ADSL system overheads and aggregate data rates ........................... ..17
`Classification by ATM options ............................................................ ..21
`
`ATU-C functional characteristics ........................................................ ..22
`
`ATU-C input and output V interfaces .................................................. ..22
`Framing .............................................................................................. ..23
`Scramblers ......................................................................................... ..35
`Fonivard error correction ..................................................................... ..35
`Tone ordering ..................................................................................... ..36
`Constellation encoder — with trellis coding ......................................... ..37
`Constellation encoder — without trellis coding .................................... ..45
`Gain scaling ........................................................................................ ..45
`Modulation .......................................................................................... ..46
`Cyclic prefix ........................................................................................ ..47
`Transmitter dynamic range ................................................................. ..48
`Transmitter spectral response ............................................................ ..48
`Transmit power spectral density and aggregate power level ............. ..49
`ATU-Fl functional characteristics ........................................................ ..51
`
`ATU-R input and output data interfaces ............................................. ..51
`Framing .............................................................................................. ..52
`Scramblers ......................................................................................... ..57
`Fonivard error correction ..................................................................... ..57
`Tone ordering ..................................................................................... ..57
`Constellation encoder — with trellis coding ......................................... ..57
`Constellation encoder — without trellis coding .................................... ..57
`Gain scaling ........................................................................................ ..58
`Modulation .......................................................................................... ..58
`Cyclic prefix ........................................................................................ ..59
`Transmitter dynamic range ................................................................. ..60
`Transmitter spectral response ............................................................ ..61
`Transmit power spectral density and aggregate power level ............. ..62
`
`1
`.2
`
`1 1 1 2
`
`3
`
`3.1
`
`3.2
`
`4
`
`4.1
`4.2
`4.3
`
`5
`
`5.1
`5.2
`5.3
`5.4
`5.5
`
`6
`
`6.1
`6.2
`6.3
`6.4
`6.5
`6.6
`6.7
`6.8
`6 9
`
`Copyright American National Standards institute
`provided by "45 unde,..ce,,5e.i/ith ANsi
`No reproduction or networking permitted without license from lHS
`
`Order Numbefi W1329754
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`Page 4 of 186
`
`

`
`ANSI T];-'-t]i3 ‘I5 — |J?E|-lI|i5lJ U5Bl:i|J'=lE‘ LIE —
`
`Page
`
`ADSL — POTS splitter functional characteristics ................................ ..63
`
`ATU-Fl to service module (TSM) interface requirements .................... ..64
`
`TA intertace definitions........................................................................ ..64
`TB interface definitions........................................................................ ..65
`
`Electrical characteristics ..................................................................... ..67
`
`dc characteristics ................................................................................ ..67
`Voice-band characteristics ................................................................. ..67
`ADSL band ......................................................................................... ..69
`ADSL noise the interference into circuit POTS ................................... ..70
`
`Operations and maintenance ............................................................. ..71
`
`Embedded operations channel (eoc) requirements ............................ ..71
`In-service performance monitoring and surveillance .......................... ..78
`Metallic testing .................................................................................... ..84
`Out-of-service testing ......................................................................... ..84
`Requirements to support OAM of the segment between
`ATU—R and SM ................................................................................... ..84
`
`Initialization ......................................................................................... ..87
`
`Overview............................................................................................. ..87
`Activation and acknowledgment — ATU-C .......................................... ..89
`Activation and acknowledgment — ATU-Ft .......................................... ..92
`Transceiver training — ATU-C ............................................................. ..93
`Transceiver training — ATU-R ............................................................. ..96
`Channel analysis — ATU-C ................................................................. ..98
`Channel analysis - ATU-R ............................................................... ..102
`Exchange — ATU-C ........................................................................... ..105
`Exchange — ATU-R ........................................................................... ..108
`
`On-line adaptation and reconfiguration ............................................ ..112
`
`The ADSL overhead control (aoc) channel ...................................... ..112
`High-level on-line adaptation — Bit swapping .................................... ..112
`Changes to data rates and reconfiguration ...................................... ..115
`
`Signaling requirements ..................................................................... ..115
`
`Loop plant, impairments, and testing ................................................ ..116
`
`Test loops ......................................................................................... ..117
`Impairments and their simulation in testing ...................................... ..119
`Test procedures................................................................................ ..121
`
`Physical characteristics .................................................................... ..127
`
`Wiring polarity integrity ..................................................................... ..127
`Connector ......................................................................................... ..127
`Wiring requirements for a remotely located POTS splitter/ATU—R .....128
`Maximum distance for a remotely located unit ................................. ..128
`Environmental conditions ................................................................. ..129
`
`Protection ......................................................................................... ..129
`
`Electromagnetic compatibility ........................................................... ..129
`
`Copyright American National Standards institute
`Provided by IHS underiicense with ANsi
`No reproduction or networking permitted without license from lHS
`
`order Number; W132g754
`Sold to:HAYN ES AND EOONE LLP [o5o4931ouoo1]— DAVID BADER@HAVNESEOONE COM
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`
`

`
`ANSI T1.-'-ll3 ‘I5 — D'?B'-ll5E| U5El::E|‘l3 D5‘? —
`
`Page
`
`ADSL sub-channel rate restrictions for default bearer rates ............... ..10
`
`ADSL sub-channel rate restrictions 2.048 Mbit/s (optional) ............... ..11
`
`Downstream ATM data cell bit rates................................................... ..12
`
`Maximum optional duplex bearer channels supported by
`transport class .................................................................................... ..14
`
`Optional duplex ATM data cell bit rates for LS2 ................................. ..14
`
`Bearer channel options by transport class for bearer rates based on
`downstream multiples of 1.536 Mbit/s ................................................ ..15
`
`Bearer channel options by transport class — Optional bearer rates
`based on downstream multiples of 2.048 Mbit/s ................................ ..16
`
`Bearer channel options by transport class for optional ATM
`bearer rates ........................................................................................ ..17
`
`Internal overhead channel functions and rates ................................... ..18
`
`Determination of aggregate downstream bit rate. .............................. ..19
`
`Determination of aggregate upstream bit rate .................................... ..20
`
`Determination of aggregate bit rate for ATM transport ....................... ..21
`
`Interface data rates for duplex channels (default configurations) ....... ..23
`
`Definition of indicator bits, ATU-C transmitter .................................... ..25
`
`eoc frame stucture .............................................................................. ..26
`
`Default fast and interleaved data buffer allocations for ATU-C
`transmitter — Configurations for bearers based on multiples
`of 1.536 Mbit/s .................................................................................... ..27
`
`Default fast and interleaved data buffer allocations for ATU-C
`transmitter — Optional configurations for bearers based on
`multiples of 2.048 Mbit/s ..................................................................... ..28
`
`Default FEC coding parameters and interleave depth for ATU-C
`transmitter — Default configurations for bearers based on multiples
`of 1.536 Mbit/s .................................................................................... ..30
`
`Default FEC coding parameters and interleave depth for ATU-C
`transmitter - Optional configurations for bearers based on
`multiples of 2.048 Mbit/s ..................................................................... ..31
`
`Fast byte format.................................................................................. ..32
`
`Synch byte format, interleaved data buffer ......................................... ..33
`
`Convolutional interleaving example for N = 5, D = 2 .......................... ..36
`
`Forming the binary word u .................................................................. ..37
`
`Relation between 4-dimensional and 2—dimensional cosets ............... ..42
`
`Determining the top 2 bits of X and Y................................................. ..44
`
`Default FEC coding parameters and interleave depth — ATU-R
`transmitter........................................................................................... ..54
`
`Copyright American National Standards lnstitute
`provided by IHS under heel-‘$5 i/llllh ANSl
`No reproduction or networking permitted without license from lHS
`
`Ofdf‘-l’ NW“b5"5 V‘/1329754
`Sold IDIHAYN ES AND EOONE LLP [U5U49B‘l UUUU1] ' DAVID BADER@HAVNESEOONE.CON|,
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`Page 6 of 186
`
`

`
`ANSI Tl.‘-I]i3 ‘I5 — lJ?2l-l1.5E| E|5EbEl"l‘-l T"l5 —
`
`27
`
`28
`
`29
`
`30
`
`31
`
`32
`
`33
`
`34
`
`35
`
`36
`
`37
`
`38
`
`39
`
`40
`
`41
`
`42
`
`43
`
`44
`
`45
`
`46
`
`47
`
`48
`
`49
`
`50
`
`51
`
`52
`53
`
`54
`
`55
`
`Figures
`1
`
`Page
`
`Fast byte format tor synchronization — Fast data buffer ..................... ..56
`
`Synch byte format for synchronization — Interleaved data buffer ....... ..57
`
`Minimum voice-band return losses at PTSN and POTS interfaces .... ..68
`
`eoc bit functions.................................................................................. ..71
`
`eoc opcode messages ........................................................................ ..74
`
`ATU-Ft data-registers.......................................................................... ..75
`
`Sync and no sync interpretation (downstream) .................................. ..85
`
`Sync and no sync interpretation for single SM ................................... ..85
`
`Sync and no sync interpretation for multiple SMs .............................. ..86
`
`Assignment of 48 bits of C—MSGS1 .................................................. ..100
`
`Assignment of 48 bits of R-MSGS1 .................................................. ..103
`
`Assignment of 48 bits of C-MSGS2 .................................................. ..106
`
`Bit pattern for C-RATES2 ................................................................. ..107
`
`Assignment of 32 bits of Ft-MSGS2 .................................................. ..109
`
`Bit pattern for R-RATES2 ................................................................. ..110
`
`aoc message headers ...................................................................... ..112
`
`Bit swap request commands ............................................................ ..113
`
`Extended bit swap request ............................................................... ..114
`
`ATU classification by category ......................................................... ..117
`
`Loop sets and maximum rates for category I and category ll testing....117
`
`Crosstalk tests for category I ............................................................ ..123
`
`Crosstalk tests for category ll ........................................................... ..123
`
`Test loops, interferers, and data rates for impulse tests for category I.....124
`
`Test loops, interferers, and data rates for impulse tests for category II....124
`
`Test loops, interferers, and data rates for POTS tests for category I ....125
`
`Test loops, interferers, and data rates for POTS tests for category II ...125
`Minimum test time for crosstalk ........................................................ ..126
`
`Pin assignments for 8—position jack and plug (RJ 31 X) at U-R ......... ..127
`
`Pin assignments for 8—position jack and plug at remote location ...... ..128
`
`ADSL functional reference model ......................................................... ..6
`
`ATU-C transmitter reference diagram .................................................. ..7
`
`ATU-Ft transmitter reference diagram .................................................. ..8
`
`ATU-C V interfaces (rates for default configuration) ........................... ..22
`
`ADSL supertrame structure — ATU-C transmitter ............................... ..24
`
`Copyright American National Standards institute
`Provided by IHS underiicense with ANsi
`No reproduction or networking permitted without license from lHS
`
`Order Number: W1829'/E4
`Sold to:HAYN ES AND BOONE LLP [U5049B‘l ouoo1]— DAVID BADER@HAYNESEOONE.COlV|,
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`Page 7 of 186
`
`

`
`ANSI 1'i..Li1.3 as I ci7aLi1.5iJ El5i':‘E.El‘l5
`
`'=lEl -
`
`Page
`“Fast” byte format — ATU-C transmitter — fast data buffer .................. ..25
`
`“Synch” byte format — ATU-C transmitter — interleaved data buffer .....26
`Fast data butter — ATU-C transmitter ................................................. ..28
`
`Interleaved data butter — ATU-C transmitter....................................... ..29
`
`Conversion of u to vand w ................................................................. ..38
`
`Finite state machine for Wei‘s encoder .............................................. ..39
`
`Trellis diagram .................................................................................... ..40
`Constituent 2-dimensional cosets for Wei’s code ............................... ..41
`
`Constellation labels for b = 2 and b = 4 .............................................. ..43
`
`Constellation labels for b = 3 .............................................................. ..44
`
`Constellation labels for b = 5 .............................................................. ..45
`
`ATU-C transmitter PSD mask............................................................. ..48
`
`ATU-C transmitter PSD mask: pass band detail ................................ ..50
`ATU—Ft data interfaces ........................................................................ ..51
`
`Fast data buffer — ATU-Ft transmitter ................................................. ..53
`
`Interleaved data buffer — ATU-F1‘ transmitter....................................... ..54
`
`ATU-Ft transmitter PSD mask ............................................................. ..61
`
`ADSL entrance unit block diagram ..................................................... ..66
`
`Test setup for transmission and impedance measurements .............. ..67
`
`Measurement method for longitudinal output voltage ......................... ..69
`
`Measurement method for longitudinal balance above 25 kHz ............ ..70
`
`ln-service surveillance of the ADSL link shown from the standpoint
`of the ATU-C ....................................................................................... ..79
`
`OAM capabilities for the segment between ATU-Fl and the service
`module ................................................................................................ ..84
`
`Overview of initialization ..................................................................... ..87
`
`Timing diagram of activation and acknowledgment (12.2-12.3) ......... ..89
`
`Timing diagram of transceiver training (12.4-12.5) ............................. ..93
`
`Timing diagram of channel analysis (12.6-12.7) ................................. ..98
`
`C-RATES1 and Fl-FlATES1 (12.62 and 12.7.4) ................................. ..99
`
`Timing diagram of exchange (12.8-12.9) .......................................... ..105
`
`Format of the bit swap request message ......................................... ..113
`
`Format of the bit swap acknowledge ................................................ ..114
`
`Overview of test setup ...................................................................... ..1 16
`
`Test loops ......................................................................................... ..118
`
`Test impulse #1 ................................................................................ ..120
`
`Copyright American National Standards institute
`Provided by IHS under license with ANSl
`No reproduction or networking permitted without license from lHS
`
`Order Number: W1829'/E4
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`Page 8 of 186
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`

`
`ANSI T]..l+]i3 ‘I5 — E|'?i':’Ll];5E|
`
`lJ5El=l3°ll:i BEE —
`
`Page
`Test impulse #2 ................................................................................ ..120
`
`Laboratory test setup for measuring performance margins .............. ..121
`
`High impedance crosstalk injection circuit ........................................ ..122
`
`lntertace on the customer premises side of the U-Ft ........................ ..127
`
`40
`
`41
`
`42
`
`43
`
`Wiring for a remotely located POTS splitter/ATU-R ......................... ..128
`44
`Annexes
`
`ATU-C and ATU—R state diagrams .................................................. ..130
`
`Power spectral density of crosstalk disturbers ................................ ..137
`
`Characteristics of test impulse waveforms ...................................... ..147
`Vendor identification numbers ......................................................... ..153
`
`Resistance and insertion loss characteristics of typical telephone
`cables ............................................................................................... ..154
`
`Overvoltage, surge protection, and EMC ........................................ ..156
`
`Examples of ADSL services and applications ................................. ..157
`
`Aspects of ADSL systems based 2048 Mkbit/s ............................... ..160
`
`Items for further study....................................................................... ..169
`
`Bibliography ...................................................................................... ..17O
`
`A
`
`B C
`
`D E
`
`Copyright American National Standards lnstitute
`Provided by IHS under license with ANSl
`No reproduction or networking permitted without license from lHS
`
`Order Number: W1829'/E4
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`Page 9 of 186
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`

`
`ANSI T].-I-l]i3 ‘I5 — D?El"1I5U U5El:U‘l? ?Tl-l -
`
`Foreword (This foreword is not part of American National Standard T1 .413-1995.)
`
`This specification of the layer 1 characteristics of the Asymmetrical Digital
`Subscriber Line (ADSL) interface to metallic loops was initiated under the
`auspices of the Accredited Standards Committee on Telecommunications,
`T1. The specification should be of interest and benefit to network providers
`and customers using multimedia services.
`
`A single twisted pair of telephone wires is used to connect two ADSL units:
`one at the central office end (an ATU-C) and one at the remote end (an
`ATU-Fl). This standard has been written to define the transport capability
`of these units on a wide variety of wire pairs and with typical impairments,
`and to help ensure proper interfacing and interworking when the two units
`are manufactured and provided independently.
`
`The ADSL simultaneously conveys all of the following: a downstream simplex
`bearer, a duplex bearer, a baseband analog duplex channel, and ADSL line
`overhead for framing, error control, operations, and maintenance. Nominal
`downstream bearer rates from 1.536 to 7 Mbit/s may be programmed. Duplex
`bearer aggregate rates from 16 to 640 kbit/s may be programmed.
`
`Two categories of performance are specified. Category I performance is
`required for compliance with this standard; performance enhancement
`options are not required for category I equipment. Category II
`is a higher
`level of performance (i.e., longer lines and greater impairments). Category
`II characteristics are not required for compliance with this standard. Three
`optional enhancements — trellis coding, transmit power boost, and echo
`cancellation — are defined for Category II equipment.
`
`A future issue of this standard may address the items listed in annex J.
`
`There are nine annexes to this standard; four are normative, and are con-
`sidered part of the standard; five are informative, and are provided for
`information only.
`
`Suggestions for improvements of this standard are welcome. They should
`be sent to the Alliance for Telecommunications Industries Solutions, 1200
`G Street, NW, Suite 500, Washington, DC 20005.
`
`This standard was processed and approved for submission to ANSI by
`Accredited Standards Committee on Telecommunications T1. Committee
`approval of the standard does not necessarily imply that all committee
`members voted for its approval. At the time it approved this standard, com-
`mittee T1 had the following members:
`
`A. K. Reilly, Chairman
`G. H. Peterson, Vice-Chairman
`O. J. Gusella, Jr., Secretary
`
`R. Welborn, Senior Editor
`J. Bingham, Technical Editor
`
`Organization Represented
`EXCHANGE CARRIERS
`
`Name of Representative
`
`Ameritech Services, Inc. .................................................. ..Laurence A. Young
`Stephen P. Murphy (A|t.)
`Bell Atlantic Corporation .................................................. ..John W. Seazholtz
`Roger Nuoho (A|t.)
`
`Copyright American National Standards Instituteprovided by [HS under rice.-we I/illth ANSI
`
`No reproduction or networking permitted without license from IHS
`
`Order l\-lumber: W1829754Sold tD.HAYN ES AND EOONE LLP [U5U49B‘l UUUU1] — DAVID BADER@HAYNESEOONE.CON|,
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`Page 10 of 186
`
`

`
`ANSI T]..lI]i3 “I5 — l'.l?E'-I150 |J5El:U‘lB E30 —
`
`Name of Representative
`Organization Represented
`Bellcore ........................................................................... ..James C. Staats
`E. R. Hapeman (Alt.)
`Bellsouth Telecommunications, Inc. ................................ ..William J. McNamara, Ill
`Malcolm Threlkeld, Jr. (Alt.)
`Cincinnati Bell Telephone ................................................ ..Thomas C. Grimes
`Renee W. Cagle (A|t.)
`GTE Telephone Operations ............................................. ..Bernard J. Harris
`Richard L. Cochran (Alt.)
`National Telephone Cooperative Association ................... ..Joseph M. Flanagan
`NYNEX ........................................................................... ..James F. Baskin
`Jim Papadopoulos (Alt.)
`Pacific Bell ...................................................................... ..Sa| R. Tesoro
`Puerto Rico Telephone Company ..................................... ..Segundo Ruiz
`Alberto E. Morales (A|t.)
`Southwestern Bell Corporation ........................................ ..C. C. Bailey
`Joseph Mendoza (Alt.)
`Sprint - Local Telecommunications Division ..................... ..Robert P. Mccabe
`Harold L. Fuller (AIL)
`US Telephone Association (USTA) .................................. ..Dennis Byrne
`Paul K. Hart (Alt.)
`US WEST ........................................................................ ..James L. Eitel
`Darryl Debault (AIt.)
`
`INTEREXCHANGE CARRIERS
`AT&T Communications .................................................... ..Charles A. Dvorak
`Dennis Thovson (AIL)
`Comsat Corporation ........................................................ ..Mark T. Neibert
`Thanos Kipreos (AIt.)
`MCI Telecommunications Corporation .............................. ..Jim Joerger
`Peter Guggina (A|t.)
`Sprint -— Long Distance Division ....................................... ..Tom G. Croda
`Peter J. May (A|t.)
`Stentor Resource Centre, Inc ........................................... ..Michel Duchesne
`B. Sambasivan (A|t.)
`Unitel Communications, Inc. ............................................ ..David H. Whyte
`George Tadros (Alt.)
`Wiltel, Inc. ....................................................................... ..Robert Bentley
`Howard Meiseles (Alt.)
`
`MANUFACTURERS
`ADC Telecommunications, Inc. ........................................ ..Ron Weitnauer
`Don Berryman (AIt.)
`Alcatel Network Systems, Inc ........................................... ..Bob Cubbage
`Dale Krisher (A|t.)
`AMP, Inc. ........................................................................ ..George Lawrence
`Jack Bradbery (AIt.)
`Apple Computer. Inc ........................................................ ..David Michael
`Ascom Timeplex, Inc. ......................................................