ith solid-state circuitry, time-division switching, and stored-program control, the
`lMENSION* PBX furnishes a host of innovative features. The new Maintenance and
`dministration Panel adds flexibility in choice of services and helps locate troubles.
`
`The DIMENSION* PBX:
`A New All-Electronic
`Customer Switching System
`
`ALLAN M. GERRISH, ROY V. LOHMILLER, AND GEORGE E. SALTUS
`
`IRST CUT INTO COMMERCIAL SERVICE in Min-
`neapolis in late January of this year, the
`Dimension PBX (Private Branch Exchange)
`has been very favorably received by its initial
`customers. The new system offers a number of
`advantages.
`For business customers, many new and use-
`ful features are included, such as call waiting
`with distinctive tones and outgoing trunk
`queuing (for automatically placing a call via
`the next free outgoing trunk). In addition,
`customers have almost unlimited flexibility
`in choosing their dialing plans and class of
`service assignments (see table, page 318).
`The new system is small, attractively styled,
`and color-matched to varying office decors. It
`is compactly housed in one or two cabinets for
`serving up to about 400 lines.
`In addition, trouble-free installation and
`reliable service are ensured by two series of
`tests performed during manufacture of the
`
`'''Trademark of AT&T Co.
`
`316
`
`new PBX: exhaustive computer-controlled
`tests of the hardware, and final tests of the
`complete system including the attendant con-
`sole and the program that implements the
`customer's chosen features.
`Finally, but certainly not the least impor-
`tant advantage of the Dimension PBX is its
`low cost. In spite of its feature capability and
`operational flexibility, the Dimension PBX
`competes very favorably in total installed
`price.
`These advantages result from putting var-
`ious advanced technologies together in the
`right combination and applying them to the
`design of a small PBX system. For example,
`the Dimension PBX has a time-division switch-
`ing network using new custom integrated cir-
`cuits. The resulting switch is low in cost, small
`in size, and high in performance. It has a ca-
`pacity of about 1700 ccs (hundred call-seconds
`per hour), sufficient for systems of about 400
`lines. System functions are controlled by
`stored programs executed by a special-pur-
`
`Bell Laboratories Record
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 1
`
`

`

`At the console. Judy Paulson, receptionist for Twin City Bottle Company in Minneapolis, talks to a caller using the Dimension PBX.
`
`pose minicomputer optimized for telephone
`call processing. This common control handles
`well over 2000 calls per hour under typical
`business conditions, a capacity that is more
`than adequate for systems up to about 400
`lines. Standard trunk circuits link the PBX to
`the Bell System network, but a variety of other
`circuits are available for connection of inter-
`location tie trunks, WATS (Wide Area Tele-
`phone Service) lines, and foreign exchange
`lines to distant exchanges.
`To make this new design a reality, a major
`tri-company effort went into the planning,
`design, and manufacture of the Dimension
`
`PBX. Work on formulating design objectives
`under the guidance of Bell Labs systems en-
`gineers at Holmdel, New Jersey began with
`market studies by AT&T Marketing and with
`Operating Company workshops conducted by
`AT&T Engineering. Western Electric and
`Bell Labs engineers worked side by side to
`scrutinize the manufacturing aspects of pre-
`liminary design, and Operating Company rep-
`resentatives contributed feedback from both
`employees and customers. Cooperation was
`also necessary in working out the manufactur-
`ing tests required for successful production.
`This close working relationship among Bell
`
`September 1975
`
`317
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 2
`
`

`

`Alphanumeric Display for
`Attendant Position
`
`Call Forwarding
`
`SELECTED OPTIONAL FEATURES OF THE DIMENSION PBX *
`Feature Package 1 (Basic Business Features)
`Provides a visual display on an attendant's console of four symbols used to
`identify the calling number, etc.
`Automatically routes to a designated extension either all calls or all calls directed
`to an extension that is busy or doesn't answer
`Allows use of a code to hold an ongoing call in order to return to a call or to
`originate another call or feature
`Allows use of a code to answer calls to other extensions within a preset pickup
`group
`Automatically holds calls to a busy extension; the called party is signaled that a
`call is waiting
`Allows attendant-seeking calls to be reassigned to selected lines and the
`assignment to remain in effect night-to-night until changed
`Provides automatic queuing of calls when all trunks are busy and automatic
`ringback when a trunk is available
`Allows an extension user to dial in a third party while the second party is held; the
`user can also hang up or drop the third party from the call
`Provides a visual indication on the attendant console when only a preset number
`of trunks remain unused in a trunk group
`Additional Features in Feature Package 2 (Centrex and Deluxe Business Features)
`
`Call Hold
`
`Call Pickup
`
`Call Waiting
`
`Night Station Service-
`Full Service
`
`Outgoing Trunk Queuing
`
`Three-Way Conference
`Transfer
`Trunk Group Warning
`Indicators
`
`Automatic Callback
`
`AIOD
`
`Automatically connects an extension to a formerly busy called number when the
`line becomes idle
`Automatically identifies extensions on outgoing calls-which permits direct
`billing to extensions for toll calls
`
`Code Restriction
`
`limits the office and area codes that can be dialed from certain extensions
`
`DID
`
`Allows direct dialing to extensions from the DOD network without attendant
`assistance
`
`loudspeaker Paging-
`Deluxe
`Remote Access to PBX
`Services
`
`Tandem Jie Trunks
`
`Trunk-to-Trunk
`Connections
`
`Provides access for attendants and extension users to voice paging equipment
`
`Allows a user calling from outside the PBX to access the PBX services via an
`exchange network connection
`Permits a caller at a distant PBX to direct-dial tie trunk calls through the switching
`system
`Allows an incoming or outgoing trunk call to be extended via the attendant to
`another outgoing trunk
`Additional Features in Feature Package 3 (Hotel /Motel Features)
`
`Calling Number Display
`to Station
`Controlled Station-to-
`Station Restriction
`
`Allows the number of a calling extension to be displayed at a called extension in
`the same PBX
`Allows an attendant to prevent certain extensions from receiving calls from other
`extensions
`Allows callers from predesignated extensions to place calls automatically without
`dialing; these calls can be directed to extensions or trunks
`Station Message Register
`Automatically records message unit information for local calls made from each
`extension
`Service (Electronic Display)
`*In addition to the standard features available to all customers.
`
`Hot-line Service
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 3
`
`

`

`Behind
`Mike
`folio w
`and A
`tool fo
`memory
`top) lin
`line ca
`and ass
`(Custo
`Labs' I
`Set to
`
`the scenes. To place a station-to-station test call,
`ckle(abol'e) of Northwestern Bell's Plant department
`he pricedures specified on a flipchart of the Maintenance
`nist ration Panel (MAAP), the Dimension PBX's new
`iagnosinq troubles and entering information into
`I: 1 h in d the MAAP is the PBX cabinet containing (from the
`I runkand processor "carriers." To the right of the
`is the Alarm Panel, with alarm and fault indicators
`ated controls. At right, Tom Cannon of the css
`Switching System) Field Support department at Bell
`t r r laboratory uses the Software Trouble Locating
`ify proper operation of a Dimension PBX program.
`
`System companies made it possible to ship the
`first system within 18 months of the start of
`the design program.
`Switching and Control
`A time-division switching network allows
`many conversations to be switched simul-
`taneously onto a common switching bus. In
`the pulse-amplitude modulation switching
`network of the Dimension PBX, portions of
`each analog speech signal are sampled at reg-
`ular intervals and switched onto a common
`bus conductor in allocated time slots. Portions
`of speech signals from other lines occupy the
`intervening time slots. Thus, a common bus
`
`with a capability of about 400 lines is time-
`shared among various conversations in prog-
`ress. Operating by means of an integrated cir-
`cuit custom-designed, for switching the analog
`signals onto the electronic bus, this system
`results in an economical, easy to engineer, and
`physically compact switching network.
`The design also permits a number of addi-
`tional advantages. For example, it eliminates
`the need for the call transfer circuits usually
`required for three-party connections, and be-
`cause of the nature of the electronic bus fur-
`nishes a high-performance four-wire switch-
`ing interface for tie trunk connections. In ad-
`dition, since many of the signaling character-
`
`September 1975
`
`319
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 4
`
`

`

`Strict environmental testing-
`essential in developing
`a sturdy, reliable PBX ...
`
`..
`
`. .. . ' ............ .
`.... .... ..... .. ..
`. ... . . . . . .. . ... . .
`.. . . ... . .... ... ..
`.. . . . . . . . . . . . . . . .
`. .. . ..... .. . . . . . .
`.................
`... . . . . . . . . . . . . .
`.................
`. . . . . .. . . . . . . . . . .
`... . .. . . . . . . . . . . .
`.. .. . ..... . . . . . ..
`. ...
`....
`
`. ........
`... .... .
`. ..... .. .
`
`Rough treatment. At Bell Labs' Denver location, members of
`the Customer Switching Physical Design department perform
`environmental tests on components and subassemblies being
`developed for the Dimension PBX. At upper left, Mas Yoshida
`sets up a test to simulate the vibration occurring during truck
`or rail transportation, and above, he controls a test setup
`simulating the shock that might occur during handling. Dan
`Arvizu, left, operates a PBX thermal simulator.
`
`320
`
`Bell Laboratories Record
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 5
`
`

`

`istics required for the various kinds of trunk
`circuits are contained in software, only four
`types of hardware trunk circuits are required.
`The choice of control circuits is one of the
`most critical elements in the design of a small,
`economical PBX. For the Dimension PBX, ad-
`vances in integrated circuit technology al-
`lowed stored-program control to be extended
`from larger electronic switching systems to
`small customer-premises switching equipment
`for the first time.
`The minicomputer designed for the system
`is a small, 16-bit machine tailored to the cost,
`physical space, and maintenance objectives of
`the Dimension PBX. It incorporates both West-
`ern Electric and commercial integrated cir-
`cuits. The main memory device is a commer-
`cial metal-oxide semiconductor (MOS) device
`containing 4096 bits of storage. Each circuit
`pack containing 17 of these devices has a ca-
`pacity of 4096 16-bit (plus one parity bit)
`words. The maximum configuration of 16 cir-
`cuit packs thus allows a maximum memory
`capacity of about 64,000 words. However, for
`each installation, the size of the memory (the
`number of circuit packs used) directly reflects
`the number of the features ordered.
`A high-performance magnetic tape cart-
`ridge is used to load the feature programs into
`the main memory. This secondary or backup
`memory contains several million bits of stor-
`age-sufficient for the main program and a
`large number of off-line programs used to
`diagnose troubles and to input or revise infor-
`mation pertaining to a particular installation.
`Software
`The assembly language used to translate a
`user's instructions for the processor is based
`on a language developed previously at Bell
`Labs for use in small electronic switching of-
`fices. A complete software support system was
`available for this language--including ed-
`itors, loaders, extensive simulation capabil-
`ities, operating system programs, and debug-
`g-ing programs (see right-hand photo, page
`319). The language offers a repertory of ap-
`proximately 150 sixteen-bit instructions tai-
`lored to call-processing applications.
`Based on this software assembly language,
`an efficient, high-level programming lan-
`guage, easy to understand and write, was de-
`veloped. Several new instructions were added
`to simplify the scanning and maintenance op-
`erations required for the Dimension PBX.
`The organization of the software programs
`
`for use in the PBX makes extensive use of
`tables to store the state of calls in progress.
`This orderly method of organizing the call
`processing programs helps to minimize the
`interaction of software with peripheral hard-
`ware units, such as the memory, network, and
`console circuits. This structure also leads to
`convenient control of various tasks, such as
`line and trunk scanning, and allows the sys-
`tem to modify task priorities under varying
`traffic conditions.
`For the initial installation of the Dimension
`PBX on a customer's premises, the class-of-
`service information (the dialing plan, direc-
`tory number translations, and system fea-
`tures) is generated by Western Electric for
`the tape cartridge provided with the cus-
`tomer's machine. This information corres-
`ponds to the features requested on the original
`order form by the customer.
`Another requirement, however, is for an
`easy-to-use method of adding or revising cus-
`tomer information on an in-service basis on
`the customer's premises. The Maintenance
`and Administration Panel (MAAP) was de-
`signed to meet this need (see left-hand photo
`on page 319). The MAAP unit also furnishes
`diagnostic information for locating trouble
`conditions and doing other maintenance tasks.
`Console
`The console for the Dimension PBX was de-
`veloped at Bell Labs in Holmdel, New Jersey.
`It is a new all-electronic design using light-
`emitting diode (LED) displays (see the illus-
`tration on page 317). Electronic design allows
`the console to be connected by a small cable
`(12 pairs of wires), which improves appear-
`ance and makes installation easy.
`A number of new features were developed
`for the console. For example, the busy or idle
`condition of the extension numbers is dis-
`played on the DSS (Direct Station Selection)
`and busy lamp field on the top panel of the
`console. A set of "grQup select" keys under
`the DSS and busy lamp field is used for select-
`ing different hundreds groups for display.
`Just above the dial pad is a set of buttons
`and lamps used for supervising the console's
`switched loops. The use of five lamps for in-
`dicating the state of a call on the switched
`loop allows flashing indicators to be reserved
`for alerting attendants and eliminates the
`need to distinguish between various lamp
`flashing rates, as is frequently required in
`many present systems.
`
`September 1975
`
`321
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 6
`
`

`

`Physical Design
`To minimize costs and to smooth the transi-
`tion from development and early production
`to high volume manufacturing required ex-
`amination of various facets of design and
`manufacturing:
`Design documentation practices were re-
`viewed to ensure that both current and new
`technology could be converted rapidly into
`manufacturing information.
`The standard and planned photographic,
`plating, fabricating, soldering, assembling,
`and testing equipment and processes were re-
`viewed to locate those that would reduce man-
`ufacturing intervals and minimize new capital
`investment.
`After evaluating the factors involved, de-
`sign engineers established equipment features
`for two important elements of the system, the
`printed wiring boards (PWBs) and the printed
`wiring backplanes (the backplanes into which
`the PWBs connect). The PWBs are about the size
`of a page of this magazine, a size that was in-
`fluenced by the desired characteristics of the
`line and trunk circuits. For example, the more
`circuits per PWB, the lower the cost per circuit.
`However, this factor had to be balanced by
`a concern for the number of circuits taken out
`of service when a PWB is removed to clear
`trouble. In this case, the best answer was four
`line circuits packaged per PWB.
`The PWBs are constructed by a photo-
`graphic, chemical-etching process. This pro-
`duces a pattern of copper conductors over-
`laid on an insulated support plane and inter-
`connected by plated-through holes. Compo-
`nent leads are inserted into the holes and
`soldered to the PWB to form a functional cir-
`cuit pack. At one end are gold contact fingers
`for interconnection to a printed wiring back-
`plane to form a "carrier," or shelf, of the Di-
`mension PBX equipment cabinet.
`The carrier backplane is also a two-sided
`printed wiring board with copper conductors
`etched on epoxy glass. The backplane meas-
`ures about 8 by 22 inches. Coaxial and tape
`cable interconnect the carriers, and 26-gauge
`connector-ended cables connect the carriers
`to the external cross-connect field.
`Line, trunk, and processor carriers are used
`in the system, and each cabinet contains up
`to five carriers. Fully equipped line carriers
`contain enough circuit packs for about 60
`lines. Fully equipped trunk carriers handle
`about 30 trunks. Line and trunk carriers may
`
`be assembled in various combinations to fur-
`nish 60, 120, or 180 lines in a single cabinet,
`or 240, 360, or 420 lines in two cabinets, de-
`pending upon traffic (the number of trunks
`needed) and customer requirements.
`Adding to the capacity of an installation is
`a simple matter of rolling in a second cabinet,
`uncrating it, and placing it in location. A
`loaded cabinet weighs a maximum of 750
`pounds and can be handled easily on its own
`rollers. By interconnecting 25 cables, installa-
`tion personnel can double the capacity of the
`system in less than an hour.
`The packaging density resulting from the
`use of high-level integrated circuits caused
`one concern in cabinet design. Could the sys-
`tem operate at the required maximum external
`ambient temperature of 120· Fahrenheit?
`Both thermal analysis and simulation were
`used to assess the rate of heat accumulation
`and to determine the combination of fans,
`baffles, and cabinet openings required to dis-
`sipate the heat. Final tests verified the proper
`operation of the PBX in an external ambient
`of 120• Fahrenheit.
`Transportation and handling tests were
`also conducted in the laboratory. Results of
`these tests were incorporated into the struc-
`tural design to ensure that the PBX would ar-
`rive factory-fresh at the customer's premises.
`Maintenance
`The long-range maintenance objective of a
`highly reliable, easy to maintain PBX called for
`the following:
`Built-in maintenance aids to help craft per-
`sonnel understand machine operation.
`Methods of isolating faults so that circuit
`packs would be replaced only as a repair pro-
`cedure with 90 percent accuracy on the first
`replacement.
`A coordinated package of maintenance hard-
`ware, software, documentation, and training
`that allows a craftsperson to solve 95 percent
`of the problems encountered in an average of
`one-half hour or less.
`The Alarm Panel on the cabinet contains
`alarm and fault indicators and associated con-
`trols. Major and minor, fuse, over-tempera-
`ture, and functional alarms are displayed on
`the panel. The functional alarms indicate
`faults in the processor, memory, network, and
`facility (such as tone generators and con-
`soles). Specific off-line programs associated
`with these alarms are paged in from the tape
`
`322
`
`Bell Laboratories Record
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 7
`
`

`

`presentation. Bob Dybevik (left) and Tony Krzmarzick
`Feat1
`f Northwestern Bell Marketing explain a novel feature
`(righ
`of the )imension PBX to Jim Wasserman, vice president of Twin
`City 1 tle Company-the product's first customer.
`
`Plan ng session. John Lees (seated), test engineer at Western
`De nver plant, goes over details of a Dimension PBX
`Elect
`test ,,
`h 'left to right) Rick Klosterman, Jim Wetsel, and
`Felix
`arciia. also of Western Electric.
`
`cartridge with the aid of the Maintenance and
`Administration Panel. The Alarm Panel also
`contains switches for a number of manually
`operated processor diagnostics and for con-
`trol of emergency power transfer.
`The Maintenance and Administration Panel
`functions in conjunction with the Alarm Panel
`and supporting TOP (Task Oriented Practices)
`documentation. Observing fault indications
`on the alarm panel, a craftsperson consults
`the TOP documentation to determine which
`MAAP procedures to use. Equipped with flip-
`charts corresponding to specific procedure
`numbers, the MAAP unit directs the craftsper-
`son in carrying out the procedures and helps
`interpret results.
`Additional maintenance aids include fuses
`for system and circuit protection, visual lamp
`displays indicating system and circuit status,
`circuit test points, and access points for mak-
`ing test calls. Audit programs and error re-
`covery procedures are also used to minimize
`the effect of ac power disturbances, low volt-
`age conditions, transient electrical disturb-
`ances, and many other potential sources of
`trouble.
`
`The best insurance of trouble-free opera-
`tion, however, is the thorough program of
`manufacturing tests instituted at the Western
`Electric plant in Denver, where the Dimension
`PBX is made (see right-hand photo, this page).
`Specific tests cover circuit packs, wiring, and
`software and include the use of "x-ray" pro-
`grams to self-test hardware and diagnose
`faults. Customized system tests cover all the
`features specified on each customer's order.
`As these tests continue to improve in speed
`and thoroughness, they should help ensure
`even more that Bell System customers receive
`the best and most reliable service that is eco-
`nomically feasible.
`To date, about 100 systems have been
`shipped from the Western Electric factory in
`Denver, and the field experience has been good
`for all concerned. Customers are discovering
`that the Dimension PBX's comprehensive pack-
`age of features offers them new ways of using
`the telephone, and Operating Company people
`are finding that the systems are easy to install
`and use. The Dimension PBX promises more
`satisfied customers as shipments increase in
`the coming months.
`0
`
`September 1975
`
`323
`
`Bell Laboratories Record Vol 53
`
`BLACKBERRY EX. 1010, pg. 8
`
`