Services for Tomorrow's PCS
`
`Susan M. Ahimovic and Joan M. Michaels'
`(908) 758-5367 /758-2020
`
`Bell Communications Research
`100 Schultz Road
`Red Bank, NJ. 07701
`
`1. I ~ ~ r o ~ ~ c t i o n
`Personal Communications Services (PCS) provides
`- the
`terminal, personal, and service mobility
`ability of an end user
`to access hidher
`telecommunications services in any location and the
`ability of the network to locate this end user as
`he/she moves. Today's telephone customers have
`come to expect a menu of "bell and whistle''
`services that provide offerings like custom calling
`features, voice mail, and operator services; that may
`be generally referred to as supplementary services.
`In order for PCS to become widely accepted by the
`public more than basic wireline or wireless services
`may be required.
`In addition to the bells and
`whistles of today, supplementary services that
`provide manageability and security of a PCS
`offering should be made available to the end user.
`This paper provides a view of an end-to-end PCS
`network as a reference for the reader. The paper
`then shifts the focus to
`the two areas of
`supplementary services that may be implemented in
`a PCS offering and provide additional revenue
`and/or preserve current revenue: personalized call
`management and fraud detection. Personalized call
`management includes services such as message
`delivery and call screening; features that may
`provide opportunities for additional revenue. Fraud
`detection addresses the need to preserve revenue via
`improved billing and fraud detection capabilities.
`2. PCS - The End-to-End Network
`A vision of personal communications, in a global
`sense, embraces
`the
`integration of several
`communications concepts, approaches or systems
`into one interconnected and interworking network.
`This vision of personal communications includes
`personal, terminal, and service mobility. Personal
`mobility includes the ability of an end user to access
`his/her telecommunications services on any terminal
`at any location and the ability of the network to
`locate that end user as he/she moves. Terminal
`mobility is the ability of an end user's terminal to
`
`The views expressed in this paper are those of the authors and do
`not reflect a Bellcore position.
`
`access telecommunications services from any
`location while in motion, and the ability of the
`network to locate and identify that end user via the
`terminal as it moves. Service mobility is embodied
`in personal and terminal mobility; it refers to the
`ability to associate services with an end user rather
`than with a particular piece of equipment or
`geographic location. Service mobility allows an
`end user's services to follow them as they move
`through the network. This kind of mobility is
`accomplished not only through wireless telephones
`but,
`through
`the
`interconnection of several
`communications networks that will provide these
`capabilities to the end user. The interconnected
`architectures include the radio (wireless) network,
`the existing wireline network (landline/locai loop),
`and the CCS/SS7 network to access centralized data
`bases. These centralized data bases are the vehicle
`that provide the personal, terminal, and service
`mobility by tracking and recording end user location
`and identification information and allowing access
`from anywhere to anywhere.
`PCS Architecture Overview
`2.1
`This section will provide a brief description of the
`PCS interconnecting architectures and elements as
`well as a discussion of the PCS capabilities. The
`network elements and interfaces in a view of an
`end-to-end architecture are depicted in Figure 1.
`
`2.1.1 Wireless Network
`The basic wireless network components are of a
`radio port control unit, fixed radio ports, and
`tetherless handsets.
`
`* The Radio Port Control Unit's2 (RPCU)
`primary function is to manage radio resources
`and to control the transport of information
`between the network and its associated radio
`ports. The RPCU communicates with the radio
`port via a line interface.
`The Radio Port (RP) provides an interface
`between the radio link and the fixed network
`* The access manager functionality may be combined with an RPCU.
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`facility. The basic functions in the RP include:
`transmission/reception, channel coding or
`decoding, synchronization with the network,
`performance measurements, termination of air
`interface, remote tests and maintenance checks,
`and power input.
`The tetherless handset is a low-powered device,
`convenient to carry, that allows an end user to
`access a network similar to today's "Plain Old
`Telephone Service (POTS). Communication
`with the network from the tetherless handset is
`via a radio link.
`There a several ways
`these
`implement
`to
`components to deploy a wireless network. For
`example, the RPCU may be combined with some
`data base intelligence to manage the information
`relating to incoming and outgoing calls for end
`users in its serving area. This implementation is
`generally known as an Access Manager (AM).
`Another implementation, known as an Intelligent
`Base Station (IBS), might be to combine the
`RPCU and an Rp to manage the serving area.
`2.1.2 Wireline Network
`The network node in the local exchange voice
`network concerning PCS is the Service Switching
`Point (SSP). The SSPs are the interface point
`between the voice network and the Common
`Channel Signaling (CCS) network(s). An SSP may
`be either an end office (EO) or an access tandem
`(AT) that has the capability to send and receive the
`Common Channel Signaling/Signaling System 7
`(CCS/SS7) messages necessary to query centralized
`PCS data bases. EOs are the point of interface with
`the telephone end user, commonly referred to as the
`local loop. An AT centralizes selected functions
`like alternately billed calls and CCS/SS7 query
`capabilities.
`2.1.3 CCS/SS7 Network
`The major components of the CCS/SS7 network
`that may be used in the PCS architecture are
`Signaling Transfer Points (STPs) and Service
`Control Point (SCP) data base application. These
`CCS/SS7 network nodes are interconnected by
`signaling links. An STP is the network node that
`performs message routing in the CCS network. The
`STP is an SS7-based packet switch that uses routing
`tables stored in memory to screen and route
`messages in the CCS/SS7 network. An SS7
`message may traverse several STPs in the route to
`its destination. A message's destination may be
`either an SSP or an SCP. The SCP serves as the
`the PCS data base
`platform
`that supports
`application. The SCP/PCS data base contains end-
`user service profile records that manage PCS calls
`and features. The SCP records and updates personal
`
`location information for PCS end users. The
`location information consists of a mapping between
`an end user's PCS number and the routing
`information used to deliver calls to the location
`where the end user is currently registered. The PCS
`data base can also enable end-user features at an
`SSP such as call management capabilities and fraud
`control, as discussed in Section 3 and Section 4 of
`this paper.
`2.2
`PCS Capabilities
`As a PCS end user moves from place to place at
`pedestrian speed, powers on, or powers off their
`tetherless handset, the I?CS network provides the
`following capabilities to provide end users with
`personal, terminal, and service mobility.
`
`2.2.1 Registration
`Registration is the process where an end user
`notifies the network of their location so they can
`receive incoming calls. If an end user is registered
`on a wireless terminal, new locations will be
`automatically registered in the network as they
`move to different areas. This process makes an end
`user known to the network and provides a method
`for incoming calls to be delivered based on the
`current registration inforimation. A PCS data base(s)
`manages
`the updating of personal/terminal
`registration information either as an automated
`process (wireless) or a manual process (wireline).
`In the automated case, the radio system detects the
`handset powering on and sends a registration
`request containing the end user's PCS number to the
`In the manual case, a routing
`PCS data base.
`address is assigned on registration from a wireline
`phone. An end user will regisier the routing
`address (i.e. a geographic telephone number) that
`will be associated with their PCS number. This
`registration may be accomplished by having the end
`user call the registration system and provide the
`registration information using DTMF signaling.
`De-registration will occur when an end user
`registers in a new area, powers-off (wireless), or the
`current registration excee.ds a time-out parameter.
`2.2.2 Authentication
`Authentication is the process whereby the identity
`of the end user requesting service is confirmed. To
`support authentication, the PCS data base must
`manage the verification of an end user's identity.
`Each end user will be assigned Personal
`Identification Number (PIN), as well as a PCS
`number and in the case of a wireless terminal, a
`unique identification number (i.e., Electronic Serial
`Number, ESN). The combination of PCS number,
`PIN, and the manufacturer-assigned ESN can be
`used to authenticate an erid user.
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`2.2.3 Service Validation
`Service validation is the process whereby the PCS
`network verifies the status of
`the end user
`requesting service and either permits or denies
`service depending on end-user status as recorded in
`the PCS data base. Service validation involves
`verifying the end user's account status and
`subscribed features and/or services. As part of the
`registration process, the network sends the PCS data
`base a validation request to make sure the end user
`is permitted to receive service. A response message
`is sent to the user's serving network to permit or
`deny service.
`2.2.4 Call delivery
`Call delivery refers to the delivery of an incoming
`call to the end user. In a wireless network the end
`user's location would be related to the RP or RPCU3
`and in a wireline network the end user would be
`registered to a geographic telephone number. Upon
`recognizing a PCS number from a call directed to an
`end user, the routing address (e.g. RP/RPCU or IBS
`location identifier, geographic telephone number)
`for this call is obtained from the PCS data base.
`Mapping the dialed PCS number to a routing
`address involves querying the end-user's service
`profile in the PCS data base.
`2.2.5 Call origination
`Call origination is the capability provided to an end
`user to originate calls from the portable unit.
`Ideally, a service validation may be done to verify
`that the end user is permitted to use the services
`In the case of a wireline-registered end
`requested.
`user, calls will be placed in the normal manner.
`2.3
`PCS from the end-user perspective
`Since each PCS network element has been
`discussed, the focus will be directed to the basic
`capabilities initially described: registration,
`authentication, service validation, call delivery, and
`call origination. The functions will be discussed
`regarding end-to-end signaling andor call flow, as
`appropriate.
`
`When an end user power's-up their portable unit it
`will send a "power-up" signal to the radio port. The
`radio port will relay the information to the RPCU.
`The RPCU will relay the information to a switch
`with common channel signaling (CCS) capabilities.
`The switch will generate an SS7 message that will
`be routed to the appropriate PCS data base.
`Included in the CCS/SS7 message is the PCS
`number and the location identifier of the radio port
`reporting that the unit has been powered-up. The
`
`In the case of an IBS, the end-user location would be related
`to the IBS.
`
`SCP will have the intelligence to look-up the PCS
`number and record the radio port location identitier
`(authentication,
`service validation and
`automatic registration). The SCP will generate a
`response message that will be returned to the
`originating switch. The response message should
`contain acknowledgment information such as "the
`user is a valid end user".
`
`When the called number is a PCS number (call
`delivery) a query is launched to the PCS data base
`to look-up and return the location identifier
`currently recorded. Once the response is received
`with the current location identifier, the call can be
`routed and completed. When this portable unit is
`not powered on the system may allow the end user
`to provide the network with a default routing
`address. This type of feature falls into the category
`of personalized call management and is discussed
`further in Section 3.
`
`A registered end user should be able to make a
`phone call (call origination) from their portable
`unit the same as they can from a tethered telephone.
`Ideally, the unit should request the end user to enter
`their PIN following the dialed number. The switch
`should then launch a query to the SCP for validation
`of the call originator (authentication and service
`validation) similar to the power-up registration
`function. The authentication of an end user
`provides the end user with a level of security from
`the fraudulent use of their portable unit. This issue
`falls into the category of fraud detection and is
`discussed further in Section 4.
`3. Personalized Cali Management
`The PCS end user will have the capability to
`determine when, if, and how
`they want calls to
`their PCS number(s) completed. As described, end
`users will have a service profile. Therefore, they
`will be able
`to select, from a menu of
`supplementary service offerings, the capabilities
`they want to customize their PCS service to meet
`their needs. This section discusses call origination,
`call completion, and call screening services thai
`might be offered to PCS end users so that they can
`personalize their service to meet the needs of their
`daily activities.
`3.1 Call Origination
`A PCS end user may want to maintain some of the
`same call-origination based custom calling features
`offered today. This section discusses some of the
`features activated by the call originator that may
`offered to PCS end users.
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`Speed dialing: This feature would provide the
`capability to include a speed dialing list in
`the service profile. The speed dialing
`service would be dependent on the local
`switch capabilities because the list would
`have to be down-loaded to the originating
`switch and then interact with the PCS end
`user.
`This feature may be
`Three-way calling:
`provided on a usage sensitive rather than
`subscription basis. Similar to speed dialing,
`the service offering would be network and
`switch dependent. If the network is capable
`of supporting the service, the PCS end user
`might be given the capability to activate the
`service by signaling the network in the same
`way
`the service works for wireline
`customers today (e.g. pressing the ' * I key on
`the touch tone pad during a call in progress).
`Calling Card Service: This service is
`provided in today's network as part of
`Alternate Billing Services (ABS). The
`calling party activates the service by dialing
`'0' plus the called number to alert the
`operator services system. Although it might
`seem unlikely that someone who has a
`portable telephone would need a calling
`card, there are instances where it would
`useful and therefore, should continue to be
`offered as a service option. Today some
`ABS offerings provide twenty Personal
`Identification Numbers (PINS) to be
`activated per line number. The flexibility of
`subscribing to calling card service as a PCS
`end user might be useful for the end user
`whose main household number happens to
`be a PCS number and would like to provide
`calling cards to other members of their
`family.
`3.2 Call Completion
`A PCS end user may want to design their service so
`that they never miss a call. In today's network calls
`may not be completed because there is no answer or
`the line is busy. Since a PCS call may not be
`completed if the PCS customer is not registered, as
`well as busy or no answer, service offerings that
`assure a PCS customer that they would not miss any
`calls are described in this section.
`
`Voice mail: Centralized switch based voice
`mail would be a natural service to offer a
`PCS customer. The PCS data base may
`contain information to determine when a
`subscriber might want calls routed to their
`subscribed voice mail system. The customer
`
`would be able to choose different suppliers
`for their voice mail and their locator service.
`Default number forwarding: This service
`offering would provide the capability to
`include a default (wireline) telephone
`number in their service profile. When they
`are not registered, all calls to their PCS
`number would be routed to this default
`number.
`Time-of-day / dray-of-week routing: This
`service offering would provide the capability
`to include a list of default numbers. The
`number selected for call completion would
`be based on the current time-of-day and day-
`of- week.
`Location number sequencing: This service
`offering would provide the capability to
`include a list of default routing numbers in
`their service profile. If the end user was not
`registered, the system would route to the
`first default number, if no answer or busy, it
`would then route to then next number on the
`list, until the call was completed. The
`service is a hybrid of the previously
`discussed service offerings: default number
`forwarding and \lime-of-day I day-of-week
`routing services.
`3.3 Call Screening
`Other situations may occ:ur where the end user may
`want to screen calls before they are completed. In
`today's network, custom calling services (e.g. call
`blocking, calling number delivery) are offered to
`wireline customers. Since these services have been
`it is
`deployed and accepted by the public,
`reasonable to assume that a PCS end user would
`also be interested in these services. Service
`offerings that would provide the capability for the
`PCS customer to personalize a call screening
`service that meets their needs are discussed in this
`section.
`
`Do-Not-Disturb service: This service might
`provide the PCS end user with the capability
`to route particulair screened calls to a default
`number or to a voice mail service when the
`end user is registered. An enhanced do-not-
`disturb service offering may also be
`provided on a time-of-day I day-of-week
`basis.
`Call blocking: This service would provide the
`capability of the PCS end user to list
`numbers that they wish not to be completed.
`The end user might want to provide a default
`routing option for these numbers like a voice
`mail service, ai default number, or a
`personalized call blocking announcement.
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`e Calling number delivery: This service would
`provide the calling number to the end user as
`the call is set up. This service would be
`dependent on the capabilities of
`the
`terminating equipment (i.e.
`the users
`handset,
`the
`terminating
`network
`capabilities).
`Calling name delivery: This service would
`provide the customer name of the calling
`party to the PCS end user as the call is set
`up. As with calling number delivery above,
`the service would be dependent on the
`capabilities of the terminating equipment.
`* Billed-number screening: This service is
`provided in some networks as part of ABS.
`The calling party activates the service by
`dialing '0' plus the called number to alert the
`operator services system. Billed-number
`screening includes collect and third-number-
`billed calls. Today some ABS offerings
`allow an end user to block or verify all
`collect calls, third-number-billed calls, or
`both. It therefore seems reasonablt: that this
`call screening alternative should be provided
`to PCS end users as well.
`
`4. Fraud Detection
`Fraud accounted for over 1 billion dollars4 in lost
`revenue in 1991 in the public switched telephone
`network. Cellular service providers also reported a
`1 billion dollar5 loss of
`revenue in 199 1 due to
`fraud. Revenue loss due to fraudulent usage of
`telephone services has been reported to be on the
`rise by both voice and cellular service providers. A
`variety of fraud schemes have been identified in
`both networks. For example, in the voice network
`"PIN hacking" is a common method to identify a
`valid calling card number/PIN combination and, in
`the cellular networks "tumbling" is a method used
`determine a valid
`telephone number/ESN
`combination.. It is reasonable to expect that loss of
`revenue due to fraud will be experienced in the PCS
`networks, as well. Fraud detection should therefore
`be an included capability in the new PCS networks
`as they are deployed. This section will address
`methods of embedding fraud detection into the PCS
`networks to reduce the risk of both the service
`providers and the end users have for fraudulent
`usage of their PCS services. Protection can be
`provided based on tetherless handsets' ESN, PCS
`numbers, and PINS. Fraud detection can be
`approached from three aspects: usage thresholds,
`usage restrictions, and data analysis.
`
`Industry source
`Indursty source
`
`4.1 Usage Thresholds
`A threshold is a usage-based counter that ilags or
`takes action when particular conditions are met. By
`alerting appropriate personnel or by sending a
`message to another network node, the counter value
`may be compared to a threshold limit and action
`may be taken based on the counter value / threshold
`limit comparison. In addition, thresholds allow for
`ranking of counter values by making the distinction
`between different usage levels within a particular
`threshold. This distinction allows data associated
`with normal levels of usage to receive a lower
`priority for examination than data which represents
`usage in excess of limit levels.
`
`Event counters may be implemented in several
`network nodes, however, the greatest benefit may
`be realized when the threshold capabilities are
`located in a centralized node. Otherwise, an event
`may be counted in several nodes resulting in an
`event exceeding the intended threshold across a
`network without alerting the fraud investigation
`team.
`
`The type of events that may be measured are:
`
`Successful Attempts - monitoring and
`measuring the number of times an event
`occurs to tlag unusually high usage;
`Failed Attempts - monitoring and measuring
`the number of
`times an even1
`is
`unsuccessfully attempted to deter the type of
`fraud the may be perpetrated by computer
`hackers; and
`Duration of a threshold event - t h e
`association of
`timing intervals with a
`threshold limit to reduce large loss due to
`one (or a few) event(s).
`Combination of thresholds - threshold
`capabilities used in conjunction with each
`other to further protect the end user.
`The following capabilities may implemented with
`regard to usage thresholds:
`High Usage Threshold (HUT) - sets a limit
`to the number of times an event may occur
`before it is determined to be suspicious;
`Time Interval (TI) - a time limit set to count
`events of concern; and
`Deactivation - a manual or automatic action
`that may be taken to prevent additional
`usage that has been determined suspicious.
`4.2 Usage Restriction
`A usage restriction is a limitation put on an end
`user's ability to perform certain functions. The
`primary purpose for usage restrictions is to limit
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`exposure to fraud. An example of a usage
`restriction would be to geographically limit the area
`that a PCS end user could place a call to (i.e.
`restricting calls to North America). This approach
`to fraud detection might also be used by businesses
`that would provide their employees with a PCS
`number, but wanted to limit excessive calls by
`employees.
`4.3 Data Analysis
`Call associated data may be analyzed to determine
`high usage, failed attempts, long duration, unlikely
`patterns of call origination, and calls made to
`unusual destinations. This analysis may take place
`in near real time or at some later datehime
`depending on the urgency of
`the results of the
`analysis. If enhanced fraud detection is desired, it
`may be desirable
`to record and retain all
`information needed to process call origination
`requests. Although several nodes in the PCS
`network may be candidates
`to collect call
`origination data, the greatest benefit would be
`realized if data analysis took place in or near a
`centralized node because all data would be in a
`central location and data administration might be
`simplied. Candidate nodes for data analysis might
`be the PCS data base or an operations system.
`
`5. Summary
`This paper provided a review of an end-to-end PCS
`network that supported the major focus of two areas
`of supplementary services that may be implemented
`in a PCS offering and may provide additional
`revenue and/or preserve current
`revenue:
`personalized call management and fraud detection.
`Personalized call management includes services
`such as message delivery and call screening;
`features that would provide opportunities for
`additional revenue. Fraud detection addresses the
`need to preserve revenue via improved billing and
`fraud detection capabilities.
`
`The architecture discussed network elements and
`capabilities required in the wireless, wireline, and
`the CCS networks to support PCS. The basic
`wireless network elements needed for PCS are an a
`radio port control unit, radio ports, and tetherless
`handsets. The components of the CCS network that
`are used in the PCS architecture are SSPs, STPs and
`SCPs. These CCS network nodes are interconnected
`by signaling links.
`
`PCS end users will move from place to place at
`pedestrian speed, power on, or power off their
`tetherless handset. The PCS network will provide
`the following capabilities to provide end users with
`personal,
`terminal, and
`service mobility:
`
`registration, authentication,
`delivery, and call origination.
`
`validation, call
`
`The two areas of supplementary services that were
`investigated in this paper identified the potential for
`a PCS end user to personalize their PCS service to
`meet the needs of their daily activities and for the
`PCS service providers to provide a private and
`secure service. The call management features
`described in this paper included features such as call
`screening and message delivery services; services
`that may provide additional revenue opportunities
`to the service provider. The fraud detection features
`described address the service provider's need to
`preserve revenue via improved billing and fraud
`detection capabilities.
`
`It may very well be that the "bells and whistles" of
`today' s telephone service are the k e y to PCS
`becoming widely acce:pted by the public as the
`telecommunications services of the future.
`
`References:
`1) no author listed, "Personal Communication Services: RBOCs Test
`PCS Maze of Opportunities and Perils." Applied Networks. Volume
`4/Issue 7, July 199 I .
`2) Daehnke. Cindy, "Wirelens Communications and the Voice
`Variable" Voice Processing Maguine. August 1991.
`3 ) no author listed. "Bellcore Sees PCS as Alternative to Wire in
`Local Loop," Advanced Wireless Communicaions. May 15,199 I.
`4) Bellcore. "Generic Framework Criteria for Universal Digital PCS"
`TA-NWT-001713. Issue 2. December 1990.
`-5) Lucas. Jerry "The Cordless Gods must be Crazy," 7elesiruiegirs.
`April 1991.
`6 ) no author listed. "The Digital Cellular Shakeout" Yankeevision.
`May 1991
`7 ) Worthman. Emest "The Spreading of Spectrum," Cornmunicurions.
`January 1991
`8) Bellcore, "Network Architecture and Services,"
`BOC Notes on the LEC Networks, SR-TSV-002275, March 1991.
`Issue 1:Section 14.
`9) no author listed. "Personal Communications are Now Highly
`Personal." U.S. Telecoriimunications. July I , 199 I .
`
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`PCS
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`Dna Base
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`Figure 1
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