Implementing Isdn In The United States

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Missouri University of Science and Technology Scholars' Mine Faculty Research & Creative Works 1-1-1986 Implementing ISDN in the United States Robert Mitchell University of Missouri--Rolla Follow this and additional works at: http://scholarsmine.mst.edu/faculty_work Part of the Electrical and Computer Engineering Commons Recommended Citation Mitchell, Robert, "Implementing ISDN in the United States" (1986). Faculty Research & Creative Works. Paper 1731. http://scholarsmine.mst.edu/faculty_work/1731 This Article is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in Faculty Research & Creative Works by an authorized administrator of Scholars' Mine. For more information, please contact [email protected]. 398 IEEE ON JOURNAL AREAS SELECTED COMMUNICATIONS, IN VOL. SAC-4, NO. 3, MAY 1986 Implementing ISDN in the United States Abstract-Planning for implementation of ISDN is proceedingata rapid rate throughout the United States. Planning for nationwide deployment of common-channel signaling to support database access, as well as internode signaling for ISDNis also underway. This paperdescribes planning for trialsandinitialapplications of ISDN andcommon-channel signaling for service starting in late 1986 throughearly 1988, as well as ISDN demonstrations, some already in operation. In addition, this paper discusses the network and regulatory environment for ISDN implementation in the United States, standards for the U S . environment, and trials of transition services. INTRODUCTION I. I MPLEMENTATION of ISDN is proceeding rapidly in the United States in response to business needs of both users and network providers. First, from the users’ perspective, users are not only experiencing growing needs for information technology, butare increasingly concerned about costs for their telecommunications needs. They see ISDN as a possible means for controlling their costs as well as providing the new capabilities needed. These new capabilities include nonvoice, digital telecommunications for information access, distribution, and processing, as well as increasingly sophisticated voice telecommunications needs. ISDN can provide the framework for satisfying their multifaceted telecommunications needs through standard digital interfaces with separate-channel signaling. Users also want greatercontrol over their telecommunications services. ISDN can provide this in the areas of service provisioning and maintenance. From the network providers’ perspective, ISDN provides a framework for meeting user needs effectively in a telecommunications industry structure that supports the procompetitive United States telecommunications policy that is discussed in Section 11-B. The ISDN standard user-network interfaces can support a wide range of services, and can serve to decouple evolution of technology in the network and in users’ terminal equipment. In addition, providers will be able to reduce and control costs of provisioning since, with ISDN,an operating telephone company need no longer deploy equipment specialized for various services. Thispaper discusses the network and regulatory environment for ISDN implementation in the United States, standards for the U.S. environment, transition service trials, goals of ISDN trials, ISDN architecture evolution, and Manuscript received October 1, 1985. Theauthoris with Bell Communications Research, Livingston, NJ 07920. IEEE Log Number 8407256. ISDN trials and early implementations in the local exchange carriers and other carriers. 11. UNITEDSTATES ENVIRONMENT A . DigitalCapabilities Digital capabilities are widely deployed in the United States networks. Digital technology was introduced starting in 1962 with T1 Carrier Systems for interoffice transmission. T1 is a 1.544 Mbit/s transmission system that carries 24 voice channels on a copper twisted pair in each direction. Throughout the 1960’s, 1 9 7 0 ’ ~and ~ into the 1980’s, other digital capabilities were deployed for economic reasons including a family of digital transmission systems on copper pairs, coaxial cables, microwave radio, and, finally, in multimode and single-mode optical fiber systems. Stored-program-control space- and time-division switches with digital capabilities and integrated digital interfaces were deployed with synergistic effect on deployment of both interoffice and loop digital-carrier systems. More than 20 years of digital deployment has resulted in the wide base of digital capabilities depicted in Fig. 1 [l]. It should be noted that the percentage of loops shown with digital capability represents nonloaded loops that are suitable for applying digital transmission technology. In some cases, bridged taps may need to be removed. The relatively low digital deployment in intercity transmission facilities reflects the economic’attractiveness of high-capacity analog transmission facilities that existed for many years for long-distance voice services. This situation is now changing due to the deployment of long-haul high-capacity digital transmission systems using optical fiber technology. B. Legal and Regulatory Impacts ISDN is envisioned by CCITTas national integrated networks evolving from telephony networks. However, in the United States, the pro-competitive public policy that has been established for the telecommunications industry has had theeffect of fragmenting the national network into subnetworks that must be interconnected. Changes in regulatory policy that are continuing to occur will have an ongoing effect on ISDN implementation. One major impact resulted from the historic final agreement between theDepartment of Justice and American Telephone and Telegraph (AT&T) referred to as the modification of final judgment (MFJ). The MFJ resulted in the 0733-8716/86/0500-0398$01.00 01986 IEEE 399 MITCHELL: IMPLEMENTING ISDN I N THE UNITED STATES INFORMATION USER NETWORKS NETWORKS ENHANCED MONITORING SERVICES ACCESS LOCAL INTEROFFICE INTERCITY INTERCITY LINES SWITCHING TRANSMISSION SWITCHINQ TRANSMISSION Fig. 1. Estimated potential digital capability in the United States. Shows for each element of the national networks the 1984 and 1990 estimates. BELL OPERATING COMPANIES Fig. 3. Local exchange telephone company erspective of the environment for ISDN implementation in tie United States. _-_---------r---------- INTEGRATED FCC IDENTIFIED CUSTOMERPREMISES EOUIPMENT (CPE) NorthwesternBe11 Paclflc Nonhwest Bell TE2 TE1 NTl NT2 S REFERENCE REFERENCE POINT PO1NT ISDN TERMINAL TE1 NON-ISON TERMINAL TE2 ADAPTER TERMINAL TA NETWORK TERMINATIONS NTI 6 NT2 EXCHANGE TERMINATION NT1 L ---------- Fig. 2. Map of United States showing the seven regions formed after divestiture of the operating telephone companies by AT&T. BOC‘s in each region are listed below the name of each regional company. Fig. 4. Depicts ISDN components and interfaces, and indicates equipment designated by the FCC as customer-premises equipment (CPE). divestiture by AT&T of the local operating telephone companies, andthe creation of seven independent regional holding companies consisting of 22 Bell Operating Companies (BOC’s) as shown in Fig. 2. These companies provide exchange telephone services within geographical areas defined as local access and transport areas (LATA’s) (intraLATA services), exchange access to competing longdistancecarriers who offer telecommunications services between LATA’s (inter-LATA services), and access to information service providers. Bell Communications Research (Bellcore) was created to furnish technical support for the B0C”sin the seven regions. Other major impacts on how ISDN is being implemented result from regulatory actions by the Federal Communications Commission (FCC) based on its second computer inquiry (CI-11). The CI-I1 decision allows BOC‘s to provide only basic transmission services,’ interconnection with customer-premises equipment (CPE), and access to enhanced services.* BOC‘s are not allowed to provide enhanced services or CPE except through a separate subsidiary unless otherwise granted a waiver from the FCC rules. The United States telecommunications environment results in an ISDN implementation from a local exchange carrier’s perspective as depicted in Fig. 3. Withn each LATA, the local exchangecarrier’s ISDN will provide basic and primary-rate access to users’ terminal equipment as shown on the left side of Fig. 3. In addition, the local exchange carrier’s ISDN .may interconnect with interexchangecarriers for connection to subscribers located in other LATA’s, as well as with inter-LATA and enhanced packet networks (value-added networks), and non-ISDN networks. In addition, subscribers can access, through the ISDN, enhanced services requiring storage of information such as database services and security monitoring services. In the FCC notice of inquiry on ISD (Docket 83-841), theFCC identified NT1as digital network channel terminating equipment, a category of customer-premises equipment that cannot be supplied by the regulated telephone companies except under a waiver. The impact of this decision on ISDN is shown in Fig. 4. Thus, in addition to the standard interfaces defined by CCITT at the S and T reference points, a’new interface is required on the network side of NT1 for ISDN’s in the United States. This interface depends on the technology chosen for the digital subscriber line in the loop. However, in its notice of proposed rulemaking, Docket 85-229 (referred to as CI-III), theFCC has proposed options which would permit’ BOC provision of NT1 without structural separation. A final decision by the FCC will be made subsequent to receipt of public comment on the options. ‘Basic services are defined as pure transmission capabilities over communications paths virtually transparent in terms of interaction with customer-supplied information. 2Enhanced services are defined as any services that em loy computer processing applications that act on the format, content, C O ~ protocol, ,, or similar aspects of the subscriber’s transmitted information; provide the subscriberadditional, different, or restructured information; or involve subscriber interaction with stored information. SERVICE 400 IEEE JOURNAL ON AREAS SELECTED C. Standards Because of the multiple interfaces that now exist in the U.S. telecommunications networks, as shown in Fig. 4, it is clear that availability of standards is of utmost importance for ISDN implementation. These standards are important for both customers and network providers to support interconnection of customers’ terminals with the network, and interconnection of different carriers’ networks, to ensure adequate network transmission performance, and to facilitate operations. Standards for the United States environmentare developed through the ANSI-accredited3 T1 Committee of the Exchange Carrier Standards Association. Based on the C C I n Recommendations and T1 standards, Bellcore has issued technical advisories detailing switch requirements for ISDN basic access [2] and primary-rate access [3] which are being used to specify digital switches for ISDN implementations in the BOC‘s. These requirements detail call-setup procedures and supplementary services. IN COMMUNICATIONS, VOL. NO. SAC-4, 3, MAY 1986 Bell/BellSouth). Servicesbeing trialed are based ondelivery to the called party of. the calling number. CLASS trials are also underway in other locations such as Austin, TX, in Southwestern Bell. -Network management and reconfiguration service. Several BOC‘s are introducing this service that will allow customers with private transmission networks to allocate transmission bandwidth from their own premises to accommodate varying voice, data, and video needs, and to reconfigure connections of up to 56 kbits/s between computers, peripherals, and digital gateways to data networks (Flexserve in BellSouth, and Customer-Controlled Network Management(CCNM) in Pacific Bell.’ This servicewill allow 56 kbit/s conference bridge applications for multipoint, one-way video, or two-point, two-way video. -Simultaneous voice and data. Several BOC‘s are providing simultaneous voice and 9600 bit/s.data to Centrex customers. Northwestern Bell is providing this service over existing phone lines to its first customer, Control Data, in Minneapolis. This service is also being provided in Philadelphia in the Bell Atlantic region. SERVICE TRIALS 111. TRANSITION Starting in. late 1986, the ISDN architecture will form a framework for providing a wide range of telecommunicatioqs services. During the transition toISDN, some of these services are being implemented in some form on today’s networks before availability of ISDN capabilities in network and terminal systems. They are being provided in response to customers’ needs, and to test public acceptance of these services. They include end-to-end digital services, such as, circuit- and packet-switched digital services, as well as private-line services and signaling services. Other services offer users control of reconfiguration of a fixed-bandwidth digital pipe. Some of these transition services are described briefly in t h s section. -Circuit-switched digital service. This service, referred toas public switched digital .service (PSDS), was first offered by Illinois Bell to trial customers in banking and merchandising using AT&T’s circuit-switched digital capability onthe 1A-ESS switch for high-speed printerand facsimile applications. A second trial of PSDS is currently underway in BellSouth, with testing by Bellcore, utilizing Northern Telecom’s Datapath capability on the DMS-100 Digital Switch. Tariffs for PSDS have been filed in Illinois Bell and Pacific Bell for data, graphics, and slow-speed video applications. -Packet-switched digital service. Most of the Bell Oper-. ating Companieshave announced plans for packet-switched service. Southern Bell, in the BellSouth region, initiated an exchange public packet-switched service (PulseLink4) in South Florida onJuly 1, 1983 [4]. -Signaling services. Trials of custom local area signaling services (CLASS) have been in progress for more the one year in Harrisburg, PA(Bell of Pennsylvania/Bell Atlantic), and as Touchstar [3] in Orlando, FL (Southern 3ANSI is the American National Standards Institute. 4Pul~elinkand Touchstar are service marks of BellSouth Corporation. IV. GOALS OF EARLYISDN IMPLEMENTATIONS As the first set of CCITT Recommendations on ISDN were being finalized in mid-1984, it became evident that the next step in the evolution toward ISDN was validation of these Recommendations through early implementations. Early implementations. provide the opportunity to design and test new network architectures thatincorporate the principles embodied in the CCITT Recommendations. Initial implementations will utilize single ISDN nodes, loopaccess systems, and terminals. Later implementations will extendto multiple ISDN nodes and require interoffice transmission and common-channel signaling capabilities. A major impact of early implementations is the stimulation of technology development by systems suppliers for all elements of the network and customer-premises equipment, such as: switchng systems, loop-access systems, interoffice transmission systems, common-channel signaling, network terminations, and user terminals. The process of specification and development of systems conforming to the CCITT Recommendations provides an opportunityto verify the applications of standards in the United States, and, in fact, has already identified areas of the standards needing further definition. Early implementations also offer the opportunity to study how services are provided within the ISDN framework, and what newservice opportunities exist to meet user needs. In addition, they offer the opportunity to verify the interworking of services provided via ISDN with services provided via existing networks, and to study how to take advantage of the potential operations efficiencies and savings. Operations procedures that will be studied inthe implementations are the testing and maintenance of ISDN Flexserve and CCNM are service marks of BellSouth and Pacific Bell, respectively. EMENTING MITCHELL: 401 IN THE UNITED STATES Fig. 5. ISDN architecture for a single switching node showing a remote switching module and remote office. loops, loop qualification, provisioning, administration, and collection of traffic data. Some of the new operations functions required by ISDN will be mechanized in operations systems. Fig. 6 . ISDN archtecture showing two ISDN switching nodes. Common-channel signaling is required. V. ARCHITECTURE EVOLUTION ISDNis initially being introduced assingle ISDN switching nodes. Subsequently, other nodes will be added as interoffice facilities and common-channel signaling capabilities are implemented that allow ISDN calls between nodes. ISDN calls betweenswitching nodes in different LATA’s will be interconnected through interexchange carriers’ networks. Fig. 7. ISDN architecture for inter-LATA service showing access to interexchange carriers. A . Single Nodes Single ISDN switching nodes supporting both basic and primary-rate access to userswill form islands of ISDN capabilities. Users will have ISDN connectivity within each node. Their services will interwork with services of users connected to existing networks. A variety of serving archtectures is possible within a single ISDN node as depicted in Fig. 5. Basic and primary-rate access interfaces can be served either out of the host switch located at the ISDN switching node, from a remote switching module located in a nearby office, or through a remote office connected via digital facilities to the node. Business customers can be served by business groups of basic-access interfaces from either the host switch ora remote module (shown as a Centrex group on the ISDN switching node in Fig. 5). Alternatively, business customers with PBX’s on their premises can access ISDN services through primary-rate interfaces via T1 lines from the ISDN nodeorremote switching module (shown at the ISDN switching node in Fig. 5). Small-business customers and residential customers can be served viasingle or multiple basic-access interfaces either from the node or remotely as shown in Fig. 5. and require common-channel signaling for interoffice signaling as shown in Fig. 6 . The local exchange company’s ISDN can be extended to multiple ISDN nodes to provide ISDN connectivity throughout the LATA. C. Connecting LA TA’s In order to provide ISDN connectivity to users in other LATA’s, an interexchange-carrier access node must be provided, as shown in Fig. 7. VI. LOCALEXCHANGE CARRIERS’ ISDN’s The first steps in the evolution of the telephone networks in the United States to ISDN are underway [ 5 ] , [6]. Trials and early implementations of the basic- and primary-rate interfaces are currently being planned in all seven regions with technical support for implementation planning by Bellcore. Announcements of ISDN trials, demonstrations, andinitial installations in the United States have been made by several BOC‘s. This section includes descriptions of these trials, demonstrations, and initial applications. A . Early Centrex ISDN Trials B. MultipleNodes Illinois Bell: The first announcement of an ISDN trial Another ISDN switching node can be added within the in the United Stateswas made in February 1985 by Illinois LATA, or, as more ISDN users are added to the remote Bell in the Ameritech region and AT&T-Network Systems. switching module, the remote module may be upgraded to This trial will utilize an AT&T 5ESS digital switch serving a second ISDN switch to form a second ISDN switching McDonald’s Corporation in Oak Brook, IL, a suburb of node. These two nodes will be linked via digital facilities Chicago, with ISDN basic-access interfaces in a Centrex 402 IEEE JOURNAL ON business group [7], [8]. Approximately 300 ISDN terminations will beprovided within the 2000-lineCentrex for integrated voice and data applications. The schedule for the trial is: installation of the ISDN switch to begin in the third quarter of 1986; terminal-to-central office testing to begin in September 1986; service to McDonald’s expected to begin in late 1986; and ISDN supplementary services turn-up planned for November 1987. The architecture for the trial is that of a single ISDN node as depicted by the Centrex group in Fig. 5. Three McDonald’s buildings within a three-mile area included in the trial-the headquarters (1500 ft from the central office), Hamburger University (8000 ft), andaccounting center (5000 ft)-will be served out of a 5ESS in Oak Brook. ISDN terminals in the trial will receive integrated voice anddata services and business-group services for both voice and data calls. Intra-Centrex packet-switched data will be available over the D channel. Applications depend on switch and terminal development. Probableapplications include: integrated personal computer and voice; modem pooling; coaxial cable elimination for new terminal-tohost connections; and key equipment replacement. The trial will also demonstratethat the ISDN architecture can provide functionality that compares favorably with a local area network in the provision of voice and data services. Intenvorking of these ISDN serviceswillbe provided with packet networks, and with circuit-switched 56 kbit/s data available in the Illinois Bell network as public switched digital service (PSDS). The Bellcore Technical Advisory [2] was used as switch requirements for the trial. The technology used in the trial will include provision of a two-wire digital subscriber line employing echo cancellation. AT&T is supplying network termination devices (NT1) for the trial, but has also provided interface specifications at the T reference point and planstoprovide interface specifications on the network side of the NT1 (seeFig.4), for other manufacturers of network terminations and ISDN terminals. A request for information was issued to suppliers of terminals in December 1984. A request for proposal (RFP) wasissued for terminals and terminal adaptors in June 1985. This included AT&T’s T-interface specification, reference to the Bellcore technical advisory, [2] and customer requirements for specific applications. Aforum for information exchange was held with terminal manufacturers in July 1985. Bellcore and AT&T have established facilities for network-compatibility testing of terminals. Upon successful completion of the trial, Illinois Bell expects to expand the number of ISDN linesserving McDonald’s, and to add additional customers to this ISDN switch. Beyond the trial, Illinois Bell has a deployment program for introduction of additional digital technologies andISDN capabilities intoits network. In the Chicago LATA, a significant number of digital switcheswill be installed by the end of 1987, allowing customers to be at most only one office away from a digital switch.All of these digital offices will be interconnected bv oDtical fiber AREAS SELECTED IN COMMUNICATIONS, VOL. NO.SAC-4, 3, MAY 1986 systems. In the future, these switches will also beconnected with Signaling System No. 7 (SS7) for interoffice ISDN signaling. (See Section VII.) Access to inter-LATA services will be provided through a digital access tandem switch. Pacific Northwest Bell: Pacific Northwest Bell (PNB) in the USWest region is also planning a Centrex business group ISDN trial starting in the same time frame as Illinois Bell’s. PNB willutilize a Northern TelecomDMS-100 digital switch at a single switching node in the configuration of Fig. 5. This node is located in the Portland Capitol central office (CO) in Portland, OR, to provide 200 basicaccess connections on a 2200-line Centrex for the U.S. National Bank of Oregon. The DMS-100switchwill be installed for initial (non-ISDN) service in July 1986. The trial will start with ISDN service provided in November 1986, and .will last for 12 months in a phased implementation. Some lines will be provided for ISDN applications in PNB’s business office in downtown Portland. U.S. Bank has 188 branches and an extensive automated teller networkthroughout the state of Oregon. Thirteen branch locations are served by the Portland’ Capitol CO. Several electronic customer services will be trialed in the U.S. Bank application. Potential bankcustomer benefits from ISDN include: improvedspeed of automated teller transactions, electronic customer account verifications for merchant check guarantees and debit card transactions, and easier and faster customer access to computerized account and rate information. Integrated workstations will be tested by executive personnel both at bank locations andat their residences.Benefits to the bank include elimination of coaxial cable to the IBM 3270 terminals. Proposed applications to be tested include: -multiple terminal to host-database access on an interactive basis utilizing B- or D-channel transmission; -transaction transmission over a B or D channel to the host-database; -group four high-speed facsimile transmission; -multiple personal-computer access to a host-database, other terminals, and personal computers, to transfer, share or store data; and -utilization of an integrated voice/data terminal device with touch screen activation and file storage capability. Future services to be tested include: -videotex library access; -electronic consumer services; -voice, data, and videoservices that utilize multiple modes of transmission simultaneously; and -enhanced security services that address encryption, audit trails, and access security using ISDN capabilities. The technology to be tested in the trial includes two-wire digital-subscriber lines using echo cancellation. . The customer’s main branch is approximately 1000feet from the central office. Different loop lengths will be tested by tying in’both automatic teller machines and branch offices at different locations accessedby the Portland DMS-100 switch. Northern Telecom is providing interface specifications at the T reference point and on the network side of the NT1. PNB used the Bellcore technical advisorv 121 as MITCHELL: IN IMPLEMENTING ISDN 403 THE UNITED STATES switch requirements for the trial. An RFP for obtaining ISDNterminals wasissued in September 1985, and a forum for information exchange with terminal suppliers was held in October 1985. Pacific Northwest Bell has a wide deployment of digital switches and optical fiber technology planned. In addition to the business applications in this trial, PNB is reviewing ISDN applications for home users. B. Mountain Bell Another USWest company, Mountain Bell, will conduct a trial of ISDN basic access in Phoenix, AZ. This trial will runfrom November 1986 through April 1987, and will provide service to three Phoenix firms-Honeywell Information Systems, Inc., Arizona State Departmentof AdministrationandDepartment of Transportation,and Telegroup, a videotex firm. Mountain Bellwill demonstrate ISDN capabilities attheInternational SwitchmgSymposium to be held in Phoenix in March 1987. The initial phase of the trial will provide ISDN out of fourcentral officesusing a singleswitching node atthe Phoenix Main central office equipped with a Northern Telecom DMS-100 digital switch as host, and three remote CHANDLERline-concentrating modules located in the Phoenix North, Northwest, and Greenway central offices using the architecture shown in Figs. 5 and 8. Phoenix has a high concentration of digital- facilities including optical fiber and digital central offices. Initially, the ISDN host-remote links will be served on copper wires. The three firms have multiple locations throughout Phoenix, and have different applications for ISDN. Mountain Bell will participate in the trial as a fourth user. Two of them utilize the Mountain Bell “Centron” business-group service. Applications based on combinations of services, and including high-speed data transmission, are, being defined by Mountain Bell in conjunction with the customers. There will be no charge tothe customers during the six-month trial period. One of the objectives of the trial is to determine costs to establish charges for ISDN services following the trial. In October 1985, Mountain Bell issued an RFP to suppliers to provide information on ISDN-compatible terminal equipment. The trial may include connection through an interexchange carrier to an ISDN central office in another city utilizing the architecture of Fig. 7. In a separate phase of the trial, Mountain Bell and GTE will test ISDN capabilities of the GTE GTD-5 EAX central-office switch as a host switch near the PhoenixNorth central office as shown in Fig. 8. Several ISDN modules will be utilized to provide ISDN basic and primary-rate access capabilities for GTEand Mountain Bell applications. The primary-rate access will provide an ISDN connection between the GTD-5 and an ISDN-capable GTE PBX. This trial will run concurrently with the trial of the DMS-100 ISDN, from late 1986 through early 1987. ISDN capabilities provided by the GTD-5 will also be demonstrated by Mountain and GTE at the International Switching Symposium. I I I . MT. BELL I I I RLCM PHOENIXNORTH PHOENIX-NORTHWEST I CUSTOMER I 1 PHOENIXMAIN ISDN DISPLAY LINES 1 WEST Fig. 8. Configuration for the Mountain Bell ISDN trials in Phoenix, Az. A third trial will also take place in Phoenix utilizing the AT&T 5ESS local digital switch. ISDN capability will be added to an existing 5ESS at the Chandler-West central office with an optical remote module (ORM) placed in Phoenix-Main. The 5ESS ISDN lines will have full interworking with the voice network. Cutover of the ISDN capability will take place in February 1987, and the trial will run through June 1987. In a later time frame, Mountain Bell is planning to interconnect other ISDN nodes servedby5ESSswitches utilizing SS7 for interoffice signaling utilizing the. architecture in Fig. 6. Afterthe trial, Mountain Bell expects to make ISDN available to other business and residence customers, and anticipates extensive home applications for ISDN including electronic mail, voice mail, videotex services for home banking and shopping, video, graphcs,and interactive services for home education courses. C. SouthernBell Southern Bell in the BellSouth region has announced an extensive “rollout” of ISDN capabilities in Atlanta, GA, scheduled to begin in mid-1987 in a phased implementation. The Southern Bell project will include three ISDN nodes using central-office switches from different manufacturers as well as interoffice signaling equipment. The architecture for the initial installation uses the generic configuration of Fig. 6 and is shown for two of the nodes in Fig. 9. These switching nodes will provide business customers with both basic-access interfaces on Centrex 404 IEEE JOURNAL ON SELECTEDAREAS IN COMMUNICATIONS, VOL. SAC-4, NO. 3, MAY 1986 I WCCC TRUNKS r7 ’INTERFACE 238: D’“ INTEPFACE SL 10 238+ users within Wisconsin Bell and other Ameritech companies simultaneous voice and data transmission on a basicaccess interface for a range of terminals, including digital telephones, personal computers,and facsimile machines. The demonstration system is installed in its own container on the back of a flat-bed truck that hasbeenmoved to several sites within the state of Wisconsin. Wisconsin Bell is installing a SiemensEWSD central-office switchwith ISDN capabilities in Sheboygan Falls, WI, in the first half of 1987. Bell Atlantic: In September 1985, Bell Atlantic, one of the seven regional companies, demonstrated the first Fig. 9 . Configuration for BellSouth roll-out of ISDN technology in ISDN system to interwork with the telephone network Atlanta, GA. through one of its existing local central offices. The initial demonstration that took place during the annual Federal business groups, and primary-rate access interfaces, and ComputerConference in Washington,DC, utilized an residential customers with basic-access lines. NEAX 61E Digital Switch supplied by NEC America, Inc. One switching node in the Dunwoody central office will The Bell Atlantic demonstration installation will include use an AT&T 5ESS digital switch. This node will serve a multiple suppliers of ISDN equipment, and provide Centrex significant number of customers with 2B + D access in a features through interconnection with the existing switched wide area of northern Atlanta. network. Two other switching nodes in the Courtland Street and TheISDN capabilities are being provided to a host Peachtree Place CO’s will utilize Northern Telecom DMSAT&T lAESS through an adjunct digital switch (SA ET) 100 digital switches to serve a wide area of downtown adding ISDN capabilities to four Centrex lines from a local Atlanta. central office. Terminals and terminal adaptors on a basicAll threenodes will be interconnected with 64CCC6 access passive-bus arrangement include ISDN integrated digital transmission facilities, and willbetied to a comvoice/data workstations, a facsimile machine, and a stanmon-channel SS7 signal transfer point (STP). dard telephone set, all served by a single Centrex line. Packet-switched service will be provided by a Northern Services demonstrated include simultaneous voice/data, Telecom SL-10 packet switch. The DMS-100will route simultaneousdata/data,simultaneous voice/voice, and X.25 traffic to the SL-10 over a DS1 (23B D’) interfa~e.~ signaling capabilities. The demonstrationincludes access of The 5ESSwill provide an X.75’ interface8 to the SL-10. an outside database through a personal computer while Connection to the packet switch for data originating in simultaneouslyreceiving a facsimiletransmissionover a non-X.25 terminals will be providedfrom the exchange single Centrex line. terminations (ET) to the switches by external packet asBell Atlantic’s program through 3486 includes evaluatsembler/disassemblers (PAD’S). Rate adaptation and staing potential service offerings, demonstrating capabilities tistical multiplexing may also be required. to customers, and evaluating the’ system capabilities for High-speed and low-speed data, and voice services will internal use. It willbeusedbyBellAtlantic’s operating beprovided to business and residential customers. Pretelephone companies-Bell of Pennsylvania, New Jersey ISDN services included in the Integrated Communications Bell, and the C&P TelephoneCompanies-to demonstrate Systems’Transtexthomemanagement trial willbe supISDN features in major metropolitan areas within the ported by ISDN deployment. region for business, government, and ultimately residence Southern Bellis pursuing transition-phase services as customers. Bell Atlantic is proceeding with plans to estabdiscussed in Section 111, andhas a program to deploy lish a pilot ISDN installation in early 1987. digital technology including optical fiber systems direct to users. E. NYNEX + D. ISDN Demonstrations NYNEXplans to evaluate both basic-access Centrex and primary-rate access at selected locations in New York Wisconsin Bell: WisconsinBell,in the Ameritech reand New England.Requirements for ISDN trials have gion, initiated a demonstration of ISDN in July 1985 using been based on the Bellcore Technical Advisories for basic a Siemens EWSD digital central-office switch. This demonaccess [2] and primary-rate access [3]. strationcontractedthrough the end of 1986,willshow NYNEX hasannounced plans to conduct a series of ISDN-related trials withSiemen’s Communications Sys664 kbit/s clear-channel capability. tems. These activities will begin in May 1986 with demon’The 23B + D’ interface is a 1 . 5 4 4 Mbit/s interface p r o p r i e t e to strations of ISDN-based capabilities and services. In midNorthern Telecom. 1986, NYNEX will install. a Siemens EWSD switching ‘The X.75‘ interface, an extension of X.75 to support transit-network information for interconnecting packet networks, wlll be available in a systemfor testing at a NewYork Telephone site in later time frame. MITCHELL: IN IMPLEMENTING ISDN 405 THE UNITED STATES SERVICE CONTROL Manhattan in preparation for the introduction of ISDN capabilities. In mid-1987, NYNEX will initiate a customer trial of the Siemens ISDN switch with both basic- and primary-rate access. POINTS F, Southwestern Bell Southwestern Bell (SWB) will implement an interoffice basic-access ISDN trial in the St. Louis, MO, metropolitan area using a DMS-100 and a SESS switch installed as two “island” ISDN’s in 1987, interconnected via 64CCC facilities and using SS7 for interoffice signaling in the second half of 1987, and extension to an inter-LATA trial in early 1988 with connections to interexchange carriers. SWB has responded to RFP’s of customers in SWB territory with ISDN proposals, and is negotiating withseveral large business customers for providing ISDN accessin the 1987-1988 time frame. G. Pacific Bell Pacific Bell has announced a four-phase ISDN field trial to be conducted in the San Francisco Bay area: starting in late 1986, interconnection of different central-office switches, including a lAESS, using digital adjunct equipment from NEC America, a DMS-100 switch, and a SESS switch; addition of 6 or more customers to the ISDN starting in the second quarter of 1987; connection of the ISDN to Pacific Bell’s SL-10-based packet-switching network via X.25 links in the third quarter of 1987; and connection of the SS7 network to the ISDN trial network in early 1988. VII. COMMON-CHANNELSIGNALING IMPLEMENTATIONS Common-channel signaling is a critical component of ISDN’s to provide for signaling between ISDN nodes. In the United States, deployment of common-channel signaling is being stimulated by the need for transaction capabilities for database access to provide equal access in support of 800 Service.’ Other new services are also expected to capitalize on the transaction capabilities of this intelligent network. Planning for implementation of common-channel signaling using ANSI-approved SignalingSystem No. 7 (SS7) specifications is underway in all of the BOC‘s. Deployment is scheduled with a phased implementation starting in 3487 and continuing through 4488. The generic target architecture adopted by BOC‘s for common-channel signaling is shown in Fig. 10. This architecture is based on the two-level hierarchy described in the Draft T1 Specification 4.705 [9], [lo]. For circuit-related signaling, pairs of local signal transfer points (STP’s)- 9800 Serviceprovidescallersdispersedoverwidegeographicalareas toll-freetelephone accesstospecificbusinessesandorganizations, hotel and airline reservations. e.g., 0 @ END SWITCHING OFFICE ENDSWITCHING OFFICE WITH SSP CAPABILITY 0 ACCESS TANDEMSWITCHING OFFICE WITHSSPCAPABILITY STPSIGNALUNGTRANSFER POINT SSPSERVlCESWITCHING POINT Fig. 10. Generic two-tier common-channel signaling architecture to support database accessand ISDN signaling. referred to as secondary STP’s in 4.705-serve end-office switches and access-tandem switches in one or more LATA’s. For database access, for example, to support 800 Service and alternate billing services (ABS), such as credit card service, a mated pair of regional STP’sreferred to as primary STP’s in 4.705-and an associated pair of service control points (SCP’s), serve end-office or tandem service switching points (SSP’S)through local STP’s or directly through the regional STP’s. All seven regions have plans for providing 800 Service using SS7. Several regions have already selected manufacturers of STP switches. -Ameritech-AT&T-Technologies selected as supplier for STP’s. -Bell Atlantic-filed plans for 800 Service to be provided in late 1988 or early 1989; RFP issued for STP selection. -BellSouth-is the first application region for the common-channel signaling network and 800 Service; Bellcore is participating in testing of the CCS network and 800 Service, and in developing guidelines for use. by all the regions in installing and testing successive applications; AT&TTechnologies #2STP selected for regional STP’s to support 800 Service and a pair of local STP’s for CLASS, other services, and the ISDN “rollout.” -NYNEX-filed for 800Service in 1988; STP selection in progress. -Pacific Telesis-Pacific Bell is currently evaluating STP’s for an assumed one-level hterarchy of four STP’s, one pair to be located in the Los Angeles, CA, LATA and one pair in the San Francisco, CA, LATA. 800 Service will be available in the Los Angeles and San Francisco LATA’s in October 1988, and in all other LATA’s in May 1988. ABS will be available in July 1988. CLASS will be available in the. San Francisco LATA in April 1988 and in the Los Angeles LATA in October 1988. -Southwestern Bell-planning a one-tier backbone architecture using a mated pair of STP’s in Texas and a second mated pair of STP’s, one inOklahoma City and one in Kansas City; STP’s to be deployed in 1986-1987. -US West-RFP issued for STP’s; service expected to start in the first quarter of 1988; implementation complete by October 1988. 406 IEEE JOURNAL ON SELECTED AREAS IN VIII. OTHERISDN’s Section VI described operating telephone company plans for implementing ISDN. Several other carriers are planning to provideISDN capabilities. Of these,AT&TCommunications has announcedits plans for deploying ISDN in itsnetwork. These plans are discussed in this section. A . A T&T-Communications AT&T-Communications (AT&T-C) has announced that it will begin offering its customers primary-rate access to its network starting in 1987. Through primary-rate interfaces, customers will have real-time, on-demand connection to current network services such as 800 Service, switched 56 kbit/s data transmission (Accunet 56 kbits/s), 1.544 Mbit/s data transmission (Accunet T 1.5 Mbits/s), and Dataphone Digital Services. Future switched services over single and multiple T1 connections expected in the 1987 time frame are 64 kbits/s, 384 kbits/s, and 1536 kbits/s. AT&T’s plans are discussed in [ l l ] and [12]. A new software generic for the No. 4 ESS switches used by AT&T-C, 4El1, is being prepared by AT&T-Network Systems to provide the ISDN primary-rate access capability. IX. CONCLUSION In the United States, activities to support ISDN implementation are in high gear. ISDN iswell suited to meet users’ needsfortelecommunications serviceswithin the competitivetelecommunicationsenvironment created by the FCC and the MFJ. In addition, ISDN is expected to reduce operating company costs in providing existing and new services. CCITT recommendations are being adopted and extended for the United States environment to ensure that they support the pro-competitive telecommunications policy in this country. In the transition to ISDN, several digital and advanced signaling services are being offered to test technologies and markets for ISDN services. ISDN is moving rapidly to implementation in the United States as many carriers have adopted ISDN as their target network architecture. These carriers have initiated trials and implementations to test ISDN architectures, customer needs, services, standards, technologies, and operations, as well as interworking of ISDN services with existing services. COMMUNICATIONS, VOL. NO.SAC-4, 3, MAY 1986 ACKNOWLEDGMENT The author would’like to acknowledge the many valuable comments she receivedonthis paper from her colleagues at Bellcore and in the regions. REFERENCES I. Dorros, “The ISDN challenge in the United States,” presented at N I T Int. Symp. 85, Tokyo, Japan, May 21, 1985. Bell Communications Research, “ISDN basic access switching and signaling requirements,” Tech. Advisory TA-TSY-000268, issue 1, Mar. 1985. - “ISDN primary-rate interface for SPC-to-PBX signaling,” Tech. Advisory TA-TSY-000035, issue 1, Mar. 1985. J. C. Ehlinger and J. L. Rosado, “IntraLATA packet switching services: Experience and evolution,” in Proc. IEEE Glohecom 1984, paper 43.1. 0. M. M. Mitchell, “ISDNs on the Rise,’’ On Commun., pp. 35-42, Apr. 1985. -, “Integrated services digital networks in theoperating telephone companies,” in Proc. ISDN/Networksfor the Future 85 (Informotion Gutekeepers), Atlantic City, NJ, May 8, 1985. R. E. Sefton, “ISDN implementation in a Bell Operating Company,” Telephony, pp. 44-48, Mar. 11, 1985. J. P. Krakora, “ISDN implementation in an operating telephone company environment,” in Proc. IEEE Inl. Conf. Commun. 1985, Paper 9.3 “Draft T1 specification of Signalling System No. 7 for use in the United States-Message transfer part,” Q.705 (Signalling Network Structure), sec. 7, pp. 6-10, T1 Secretariat, Parsippany NJ, 1985. “Bell Communications Research Specification of Signalling System Number 7,” Tech. Ref. TR-NPL-000246, vol. 1, Q.705, sec. 7, issue 1, 1985. J. Fehlauer and P. G. Spring, “ISDN is alive and growing in the AT&T Communications Network,” in Proc. IEEE Int. Conf. Commun. 1985. paper 9.4. P. J. Marino and D. A. Wood, Jr., “AT&T Communications ISDN plans,” in Proc. IEEE Int. Conf. Commun. 1985, paper 9.6. Olga M. MracekMitchell (”82) received the B.A. degree in physics, and M.A. andPh.D. degrees in nuclear physics from the University of Toronto, and the M.S. degree in advanced business from Pace University, New York, NY. She is District Manager at Bell Communications Research responsible for planning trials and implementations of Integrated Services Digital Networks (ISDN) in the Bell Operating Companies. In previous positions, she was District Manager at AT&T responsible for design specification of digital transmission systems including optical fiber systems, and Supervisor at Bell Laboratories in digital signal processing and acoustics research. She chaired the Electronic Industries Association Committee TR-44.1 on Optical Fiber Systems. She has published papers in communications and physics, and has been awarded five patents in digital signal processing. Dr. Mitchell is a member of the American Physical Society and a Senior Member of the Society of Women Engineers.