Divestiture: A -Record
`of Technical
`Achievement
`Frederick T. Andrews, Jr.,
`Vice President- Technology Systems,
`Bell Communications Research
`
`This adicle touches on some of the
`technical accomplishments that have
`occurred at Bell Communications
`Research and throughout the industry,
`as the result of divestiture
`
`T he two years preceding the divestiture of the Bell
`
`A major aspect of this task has been the design and
`of speculation about the
`System was a time
`introduction of software in telephone switching systems
`perilous journey we were all about to undertake. From
`to implement the new switching and transmission
`equal access [2]. This has been a
`my current vantage point in
`Bell Communications
`features needed for
`Research (Bellcore) almost two years after divestiture, I
`major challenge and
`is being accomplished in the
`a large-scale
`shortest intervals yet achieved for such
`can say that the telecommunications technologists in
`software deployment. Of course, planning for this work
`this country can justifiably
`feel proud of
`their ac-
`was already underway in response to the negotiations
`complishments these past several years.
`involving AT&T and the competing interexchange
`Just some of the technical accomplishments of which I
`am aware are: the division of the Bell System network
`carriers (at a series of Federal Communications Com-
`mission run meetings titled “Exchange Network Fa-
`and the separation of the Bell Operating Companies’
`cilities for Interstate Access” (ENFIA)) and in response
`(BOCs’) operations systems databases into inter- and
`to then anticipated legislation, in particular Senate Bill
`intra-LATA portions; the excellent progress being made
`in the implementation of equal access facilities, a
`S.898). The MFJ converted a high-priority commitment
`massive job; the network growth
`of the interexchange
`carriers to take advantage of the opportunities afforded
`by equal access; the reconfiguration and rebuilding of
`the BOC networks; the creation of active industry-wide
`standards activities; and the successful creation
`of a
`common technical resource by the BOC’s (that is, Bell
`I won’t
`Communications Research). In this article
`describe all these accomplishments, but I will touch on
`several which I have been able to observe firsthand. .
`
`. . . telecommunications
`technologists in this country can
`justifiably feel proud of their
`accomplishments these past
`several years.
`
`Equal Access Considerations
`When considering the many technical issues intro-
`duced by the massive restructuring
`of the telephone
`industry which took place on January
`1, 1984, the
`foremost is the requirement for equal access as spelled
`[I]. The
`out in the Modified Final Judgment (MFJ)
`divested BOC’s are committed by the MFJ to provide
`exchange access service to
`all interexchange carriers,
`equal in type and quality to that provided to AT&T. By
`September 1, 1984, each BOC began its equal
`access
`service and the implementation program
`is now well
`along. It is expected that by September 1, 1986, equal
`access will be offered in all 164 Local Access and Trans-
`port Areas (LATA’S).
`
`to implement equal access arrangements to a definite
`schedule of deployment which was part of the agree-
`ment. The MFJ negotiations also brought about more
`rapid closure on the dialing features to be provided than
`had been possible in the negotiations among the parties
`involved u p x t i l that time.
`An importarkt goal of the equal access requirement is
`to enable telephone subscribers to make a per call
`specification of interexchange carriers. This requires
`modification of switching systems to accept and use a
`three-digit carrier designation to route calls to different
`on every
`interexchange carriers. Dialing extra digits
`inter-LATA call would be a burden for those who gen-
`erally use the same carrier for every inter-LATA call.
`
`December 1985-Voi. 23, No. 12
`IEEE Cornmunicatlons Magazine
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`In fact, the principle of minimizing the effect of equal
`access on service has affected more of the software and,
`hardware in the involved end offices and access tandems
`than might
`be imagined. For instance, software for
`vertical features
`and business features all had
`to be
`modified to work properly in the new environment.
`A second major aspect of equal access has been the
`development and introduction
`of a two-level hier-
`archical network design for the LATA'S that provides
`transmission quality for all interexchange carriers equal
`to that provided to AT&T [3]. T h e upper-level switching
`machines of the hierarchy are called access tandems, and
`the reason for having them is to allow small volumes of
`traffic to be economically routed
`to various inter-
`exchange carriers. When the volume of traffic between a
`particular equal
`access end office and a particular
`interexchange carrier warrants, direct trunk groups may
`be established. The network design is shown in Fig. 2.
`Access to the interexchange carrier at its point
`of
`termination (POT) can be provided three ways: 1) by
`routing traffic directly from an end office, 2) by routing
`3) by
`traffic via a concentrating access tandem, or
`
`establishing a high-usage direct route with overflow via
`the access tandem. Calls via the access tandem include an
`extra link, raisihg the question
`of whether the trans-
`mission performance can
`be equal. After the trans-
`mission design was developed, which assigned zero loss
`(see Fig.
`to the tandem inter-LATA connecting trunks
`2), the expected voice performance
`of the plan was
`modeled and the quality of service was estimated [4].
`This modeling was possible only because'
`the
`of
`extensive work over the past two decades in modeling the
`subjective effects of network transmission parameters.
`. -..
`-."
`TO INTEREXCHANGE NETWORK-
`..-"I
`
`~ I "I
`
`I-
`
`t
`
`I "
`
`".. ."
`
`Fig. 1 . Dialing patterns for access to
`interexchange carriers.
`
`So the switching systems are being modified to accept
`a presubscribed carrier for each customer.
`This is
`a feature that emerged
`in negotiations leading to the
`MFJ. After presubscribing, the customer can dial all
`cails which involve their presubscribed carrier in the
`same manner as AT&T calls
`were dialed before
`divestiture.
`To use a different carrier than the presubscribed one, a
`customer prefixes the call with the digits "10" and the
`three-digit carrier identification code for the specific
`interexchange carrier that is desired. T h e presubscrip-
`tion approach is a sensible way to minimize the effects of
`divestiture on the service provided to network users. T h e
`dialing patterns used to access interexchange carriers
`that are using this feature are illustrated in Fig. 1.
`Another example of minimizing the effects on the user
`is the forwarding of the calling station number to the
`interexchange carriers who want this supplemental
`information for billing purposes. This was essential to
`eliminate the need for manual entry of an identification
`number by the customer after reaching the chosen
`interexchange carrier, which was also only possible from
`tone-dialing telephone stations. To provide the calling
`subscriber identity without adding perceptible delay in
`toll set-up took some real ingenuity.
`was to extend
`T h e technical solution arrived at
`automatic ' number identification (ANI)
`by sending
`as
`forward the calling station identification number
`soon as the chosen carrier and destination central office
`were known by the originating central office. Hence,
`i
`ANI transmittal overlaps I.he entry of the last four dialed
`j
`i
`digits from the customer, eliminating any extra delay in
`all but very exceptional c;ases.
`
`1
`
`f
`
`HtGH .TRAFFIC
`LOW TRAFFIC
`
`EQUAL ACCESS
`EQUAL ACCESS
`END' OFFICE
`END OFFICE
`.-. .x^_ .. -~~
`.
`"^ I. ..__ .
`".__I .
`I .___^I. I
`Fig. 2. Equal access network design.
`
`_ ~ I "
`
`~~
`
`;
`
`'
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`55
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`December 1985-Vol. 23, NO. 12
`IEEE Communications Magazine
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`T h e customer opinion model used was the Long Toll
`Model [ 5 ] , based on the opinions of over 10,000 Bell
`System customers who had just completed calls
`over
`long toll connections.
`T h e predictions showed that
`performance would meet the underlying objective
`of
`equal quality. Experience with actual equal
`access
`implementation is confirming these conclusions.
`
`system was
`more, a completely functioning PICS
`AT&T Communications to manage
`replicated for
`equipment added to their inventory by the intra/inter-
`LATA split.
`In the case of the TIRKS system, the work to support
`divestiture is still continuing within Bellcore. T h e 21
`TIRKS systems deployed in the BOC’s are
`used for
`circuit provisioning.
`T h e databases of each system
`contain the detailed records on about a million circuits
`each. T h e data from these records had to be combined
`with data resident in other automated systems to build a
`complete record of circuits and inventory. This data
`gathering effort was followed by the determination o f
`asset ownership and circuit control. Next, points
`of,
`interface on each circuit were determined. Finally the
`
`Looking back, we can now
`recognize that it was
`telecommunications technologists
`who unleashed the forces that led
`to the revolutionary changes that
`have rocked the industry.
`
`Partitioning of the Network
`T h e division of a single, interconnected Bell System
`into 164 LATA networks and an inter-LATA network
`occasioned major technical challenges’
`beyond equal
`access implementation. AT&T Communications
`was
`assigned 80 percent of the then existent 4ESS large toll
`switching systems, all the TSPS operator service posi-
`tion systems for toll
`and assistance, and the extensive
`common channel signaling network interconnecting
`the higher levels of the switching hierarchy. On the other
`
`hand, the BOC’s retained all those switching offices then
`being used for local service.
`Interfacing of the long distance common channel
`signaling with local switching offices was in the very
`earliest stages of evolution at the time of divestiture. T h e
`fundamental goal of networking all stored-program
`controlled (SPC) switching systems with data links was
`deferred until a new plan in which all interexchange
`carriers could participate was available. While of great
`to be
`data were separated into two partitions, one
`long-term importance, the evolution of the SPC network
`retained. by the BOC and the other to be handed off to
`has been second in priority to the immediate need
`to
`.AT&T Communications. The process will not be fully
`restructure the LATA networks.
`completed until 1986.
`Each BOC had
`to develop a plan for interexchange
`Having split the ownership and control of the existing
`
`access tandems as well as for tandems to’ carry intra-
`
`network, many network planning and service provision-
`LATA traffic. In many cases the functions have been
`ing processes had to be changed so that the networks
`combined. Tightly integrated facilities had to be sorted
`would continue to work together. For example, pre-
`
`out; the MFJ does not allow facilities to be jointly owned
`divestiture, the design
`of a switch-to-switch message
`by the BOC’s and AT&T Communications (although
`trunk was always the responsibility of a single company,
`sharing of facilities is allowed for a transitional period).
`either one of the BOC’s or A T & T Long Lines, regardless
`This sorting out of facilities involved another massive
`of equipment ownership. In the post-divestiture environ-
`software development effort, this time centered about the
`
`ment, design responsibility for switched exchange access
`operations support systems called PICSIDCPR and the
`services goes hand-in-hand with equipment ownership,
`TIRKSTM system. Both of these systems are maintained
`and the ownership of an end-to-end circuit is now split
`and enhanced by Bellcore. PICS/DCPR’ is short for
`
`between BOC’s and interexchange carriers. This creates a
`Plug-in Inventory Control System with Detailed Con-
`to meet the
`need for trunk segment design methods
`tinuing Property Records, and TIRKS stands for Trunks
`demanding requirements
`of
`the equal
`access trans-
`Integrated Records Keeping System.
`mission plan [6].
`T h e types of
`trunk segments that
`comprise a BOC
`to interexchange connection are
`illustrated in Fig. 2.
`A most important result is that characteristics which
`were always handled implicitly now have
`to be made
`explicit. New codes have been specified which now
`enable two companies, a BOC and an interexchange
`carrier, to design their trunk segments so that the overall
`trunk will meet specified performance objectives. Soft-
`ware has been developed in the TIRKS system to support
`the message trunk design process.
`As mentioned earlier, .divestiture interrupted the
`progress that was being made towards a stored-program
`controlled network. Not only were the BOC’s left with no
`common channel signaling (CCS), but
`they were
`left
`wi’th no 800 Service database since this established
`service was assigned to AT&T. The BOC’s are now
`planning to provide equal access 800 Service for all
`
`well established mechanized
`PICWDCPR is the
`system that the Bell Companies have been using for
`plug-in equipment inventory and materials manage-
`ment. Part of the PICS system is a detailed investment
`database supporting the accounting
`records for all
`central office equipment (not just plug-in equipment).
`These records, in
`19 separate installations which
`contained a total combined central
`office investment
`base of $53 billion worth of equipment, had to be sorted
`into intra- and inter-LATA segments by January 1,1984
`-... so that each company would begin its post-divestiture
`life with a proper set of investment records for regulatory
`purposes.
`new
`This tremendous effort, which required major
`features in PICSIDCPR, was completed on time with
`minimal disruption to regular BOC functions. Further-
`
`December 1985-Voi. 23, No. 12
`IEEE Communlcatlons Magazine
`
`56
`
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`

`lease
`
`intra-LATA 800
`as well as.
`interexchange carriers
`Service. They are planning to implement CCS systems
`...
`and databases for translating 800-numbers to actual
`network terminating numbers. The Signaling System 7
`protocol established by the International Telegraph and
`Telephone Consultative Committee (CCITT) will
`be
`used by the BOC’s since ic is best suited to the long-term
`
`evolution of their LATA networks. Once CCS is in place
`
`in a BOC network it will be useful for many new network
`capabilities including future integrated services digital
`network (ISDN) services.
`Another important function which was split between
`the BOC’s and AT&T Communications was operator
`services. AT&T retained toll and assistance operations
`and the associated TSPS systems. T h e BOC’s retained
`directory assistance and intercept operations and the
`systems which support these functions. T h e BOC’s are
`implementing plans to replace the intra-LATA toll and
`assistance operator services functions now leased from
`AT&T Communication!; with their own operator
`systems. This process has already begun.
`In this first phase, the BOC’s will continue to
`access to AT&T’s CCS and their Billing Validation
`Application for calling card
`service. Later each BOC
`may deploy its own dat,abases and
`use its own CCS
`networks for intra-LATA calling card service. A major
`technical challenge that BOC’s are attacking with the
`technical support of Bellcore is to .establish a modern
`system and network structure on which they can build
`future services.
`Network Compatibility
`An important requirement of the MFJ was that the
`newly established region’s move as rapidly as possible
`toward the procuremenl: of products
`to meet their
`internal network needs independent of AT&T and of
`each other. T h e key to this is the development of generic
`requirements and modular interfaces unrelated
`to any
`specific manufacturer’s products. These generic require-
`ments and modular interfaces promote compatibility in
`the exchange networks. In the high technology, high
`risk areas o f the BOC nel.works, Bellcore has provided
`technical support throwgh a structure
`of Technical
`Advisories, Technical References and Technology Re-
`quirements Industry Forums [7]. This information flow,
`chronicled in the Bellcore Digest of Technical Informa-
`tion [8] and positioned to:represent the best view of BOC
`common needs, recognizes that there will be individual
`BOC variations to meet
`Itheir individual network and
`service strategies. While much remains to be done, the
`process appears to be working well in providing
`telecommunications industry vendors with the informa-
`tion needed to be effective entrants into the markets of
`their choice.
`
`New Standards Environment
`T h e restructuring of thc telecommunications industry
`into customer,
`exchangle carrier and interexchange
`carrier subindustries has had a profound
`effect on the
`awareness and importancle of telecommunications stan-
`dards in the U S . T h e role that AT&T played for over a
`century in planning the national telecommunications
`
`network ended with divestiture.
`In the months preceding the divestiture, the FCC
`published a Notice of Proposed Rulemaking in which it
`expressed concerns for network continuity and the need
`to provide the intercon-
`for a planning mechanism
`nection and interoperability standards
`necessary to
`assure the viability of public telecommunications made
`u p of multiple networks.
`T h e notice evoked broad industry support for a new
`national telecommunications committee which
`was
`proposed by the Exchange Carriers Standards Associa-
`tion (ECSA), an association of the major telephone
`operating companies.
`ECSA proposed a committee
`which would operate under the rules of the American
`National Standards Institute (ANSI) and
`be open in
`membership to all interested parties.
`T h e ECSA-sponsored committee was initiated in
`February 1984 as Committee T 1 [9]. T h e interest in
`telecommunications standards was such that T1 im-
`mediately attracted a membership which made it the
`largest ANSI-affiliated committee.
`T l ’ s membership
`currently numbers more than 120 member organizations
`representing exchange carriers, interexchange carriers
`and resellers, manufacturers and vendors, user groups,-
`government agencies and consultants- With the growth
`in multinational companies, Tl’s members represent
`companies with affiliations in countries such as Canada,
`Japan, Sweden, FR Germany, and France.
`T l ’ s focus is on interconnection, interoperability and
`performance standards, which are major concerns to the
`of
`U.S. network. However, in addition
`to its goal
`deriving American National Standards, T1 has been the
`principal source of contributions to the U S . CCITT
`Study Groups on matters such as ISDN and
`CCS.
`Acceptance of U S . positions in this arena is in -the best
`U.S.
`the U.S. network providers and
`interests of
`manufacturers seeking world markets.
`T 1 is organized into six Technical Subcommittees (see
`Fig. 3) and more than 20 specialized Working Groups.
`All the entities resulting from divestiture, particularly
`Bellcore as the BOCs’ technical resource, figure promi-
`of
`nently in the Working Groups. Some
`the draft
`standards o n which T 1 has worked are listed in Fig. 4.
`
`Fig. 3. Committee TI Technical Subcommittees.
`
`57
`
`December 1985-Voi. 23, No. 12
`IEEE Communications Magazine
`
`000004
`
`

`

`T1 ’s success is a compliment to an industry which has
`undergone such major changes within a short period of
`
`time. T1 has brought all interested elements together in a
`cooperative industry forum for the purpose of develop-
`ing mutually beneficial industry standards. T l ’ s success
`and its acceptance b y the industry prompted the FCC
`t o
`give T1 its vote of confidence as the source of network
`standards in March 1985.
`- ... ”. .. -
`. - -- I.- - .-. -. - ”.
`.. . il.
`. I
`
`
`
`ISDN User-Network Basic Access Signaling
`Specification
`
`,I
`j
`
`I
`
`(
`
`
`
`I
`‘2.
`!
`
`Standard For ISDN Basic Access lnterface For
`Application At The Netviork Side
`
`Of The NT1
`
`”
`
`~
`
`’3.
`
`. <
`
`US Standard For Common
`
`Channel” Signaling
`
`14.
`
`A Switched Access
`Compatibility Standard For
`lnterface Between An Exchange Carrier And An
`Interexchange Carrier
`
`5.
`
`i
`
`lnterconn,ection Of Cellular Radio Service Systems
`Exchange Wireline Systems
`
`.6.
`
`Digital Networks Synchronizltion Standards
`
`7 .
`
`I
`
`’ 8.
`
`I
`
`32 KBPS ADPCM (Low Bit Rate Voice Algorithm And:
`Line
`
`A User-System Language For Telecoinniunicatlon
`. .-. - -
`..hl_et_v_vorks.”_..-.
`.. __ _- __ . ” .” -. . -” . .- - ””.”
`Fig. 4 . Examples of work toward draft standards
`by Committee T I .
`
`‘
`
`
`
`I
`i
`I
`
`^;
`
`i
`!
`
`I
`
`‘
`
`I
`i
`j
`1
`e
`- 1
`To;
`i
`I
`
`I
`
`I
`
`!
`,
`i
`
`” ”.~.
`
`Challenges Met and Remaining
`it was
`Looking back, we can now recognize that
`telecommunications technologists who unleashed the
`forces that led to the revolutionary changes that have
`rocked the industry. At this critical time, telecommunica-
`tions technologists have risen
`of
`to the challenge
`implementing the networks thatdivestiture required on
`a n extremely rapid schedule. T h e voids which many had
`feared in the post-divestiture structure have been partly
`fiiled by the establishment
`of Bellcore, an effective
`technical resource to supplement the technical staffs of
`the BOC’s, and the creation of ECSA and its Committee
`T1 to deal with network interface issues. Perhaps most
`telling, the test of keeping the U.S. network functioning
`through the transition has been met.
`This is not to say that all problems have been solved. A
`key question that remains
`is, “How can the
`U.S.
`maintain a position of leadership in providing new
`capabilities in a public network that has such divided
`responsibility?” Technical plans for the public network ,
`must be responsive to user needs, and users are concerned
`with end-to-end solutions
`to their communications
`problems. Now a typical domestic long-distance call can
`involve two providers of customer premises equipment,
`two exchange
`access carriers, and an
`interexchange
`
`December 1985-Vol. 23, No. 12
`IEEE Communications Magazine
`
`carrier. Not only is it difficult to resolve problems with
`existing services, but there is no single driving force for
`new public network services o n a national basis. ISDN
`standards will provide a framework for digital services
`but not the detailed service definitions. Unless. some
`solution can be found to this problem of driving new
`pubiic network services, it is hard to imagine how the
`full benefits of ISDN capabilities can be achieved in the
`U.S. environment.
`References
`[I] R. A. Mercer, “What equal access means to the Telcos,”
`Telephone Engineer Q Management, pp. 99-101, Nov. 1,
`1983.
`[2] J. W. Dougias and G. Profili, “Inside the switch to equal
`access,” Bell Communications Research Exchange, Sept.1
`Oct. 1985.
`[3] D. M. Mardon, “Plan for access, tandem and trunking,”
`Telephone Engineer& Management, pp. 140-142, Nov. 15,
`1983.
`[4] B: Manseur, H. S. Merrill, T. C. Spang, and M. E: Vitella,
`“Estimated voice transmission performance of equal access
`service,” Conference record, ICC ’85, pp. 347-353, 1985.
`[5] J. R. Cavanaugh, R. W. Hatch, and
`J. L. Sullivan,
`“Transmission rating model for use
`in planning of
`telephone networks,” Conference record, Globecom ’83,
`pp. 683-688, 1983.
`[6] R. M. Fredericks, “Design ,of switched exchange access
`service,” Conference record, Globecom
`’85, to be pub-
`lished.
`[7] G. T. Hawley, S. K. O’Brien, and L. R. Benke, “What in the
`world is a TRIF?,” Telephony, pp. 100-106, May 6, 1985.
`[8] Bellcore Digest
`published
`of Technical Information,
`monthly by Bell Communications Research.
`[9] I. M. Lifchus, “StandardsCommitteeTl-Telecqmmunica-
`tions,” IEEE Communications Magazine, pp. 34-37, Jan.
`1985.
`
`Frederick T. Andrews received a B.S.E.E. from Penn State in
`1948. In that same year he joined Bell Laboratories where he did
`research in the field of switching circuits and systems. In 1958,
`he became Department Head of a systems engineering group
`responsible for transmission objectives
`and maintenance
`procedures for both telephone and data transmission. In 1962,
`he became Director
`of a Center working on telephone
`transmission systems. In subsequent assignments, he had
`responsibility for military communications, and development
`of electronic systems for subscriber loops. In 1979 he became
`Executive Director-Switching Systems Engineering Division,
`where he was responsible for resolving the systems issues
`behind the evolution of
`the network
`of stored-program
`controlled switching systems. In March 1983 he became
`Executive Director-Technology Systems Planning Division’
`with the responsibility for assembling the systems engineering
`organization for the divested Bell Operating Companies. Mr.
`Andrews is now Vice President-Technology Systems for Bell
`Communications Research, Inc. He has been an IEEE Fellow
`since 1973. He has served as IEEE ComSoc Technical Affairs
`Vice President 1982-1983 and is now ComSoc Vice President.
`In 1980, he was the recipient of ‘the Edwin Howard Armstrong
`achievement award and in 1985 he received the IEEE Award in
`International Communication.
`
`000005
`
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