CA2264252C - System and method for subscriber activity supervision - Google Patents

Abstract

A system and method for monitoring the activity of a mobile subscriber in a GSM-based PLMN system (1150) from an Intelligent Network (IN) telecommunications system comprising several Intelligent Peripherals (IPs) (1111-1114) connected to a Service Control Point (SCP) (1101) over a network. The detailed technique is automatically initiated when the Service Control Point (SCP) (1101) of an IN system attempts to reach a mobile subscriber and fails. In the first phase, the SCP (1101) arms an SMS-IP (1114) using a dummy SMS message (1181). Upon the detection of renewed subscriber activity of a mobile subscriber (1165) who was previously inactive or unreachable, a PLMN triggering notification is generated. In this second phase, the PLMN (1150) transmits an alert (1183) to the SMS-IP (1114) which in turn notifies the SCP (1101).

Description

1015202530CA 02264252 2005-02-04WO 98/09464 PCT/SE97/01370SYSTEM AND METHOD FOR SUBSCRIBER ACTIVITY SUPERVISIONCROSS REFERENCES TO RELATED APPLICATIONSThis Canadian Patent Application contains subject matter related to the following, USGranted Patents. 1) SYSTEM AND METHOD FOR CONTROLLED MEDIACONVERSION IN AN INTELLIGENT NETWORK, US Patent 5,838,768, grantedNovember 17“: 1998, in the names of Bo Arne Valdemar ASTROM, Robert JohannesBernardus SCHMERSEL, Gulamabbas SUMAR and Bj'o'rn Arne SVENNESSON; (2)SYSTEM AND METHOD FOR INCOMING AND OUTGOING INTERROGATIONSFOR STORE-AND-FORWARD SERVICES, US Patent 6,055,302, granted April 25"‘,2000, in the names of B0 Arne Valdemar ASTROM, Robert Johannes BemardusSCHMERSEL, Gulamabbas SUMAR and Bjém Arne SVENNESSON; and (3) SYSTEMAND METHOD FOR IP-ACTIVATED CALL SETUP, US Patent 6,005,845, grantedDecember 21“ 1999, in the names Bo Ame Valdemar ASTROM, Robert Johannes BemardusSCHMERSEL, Gulamabbas SUMAR and Bjorn Arne SVENNESSON; and (4) A SYSTEMAND METHOD FOR ROUTING MESSAGES IN RADIOCOMMUNICATIONSSYSTEMS, US Patent 6,108,559, granted 22” August 2000, in the names of B0 ASTROMand Roland BODIN.The present Patent Application and all the related granted patents identified abovehave been assigned to Telefonaktiebolaget LM Ericsson (publ).DESCRIPTION1. Technical Field of the InventionThe invention relates to the provision of supplementary telecommunications services,and more particularly, to a system and method for facilitating the monitoring of activity of amobile Subscriber.1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/013702. Description of Related ArtCustomer demand for customized telecommunications services has beengrowing ever more rapidly. Special subscriber features such as Call Waiting, CallForwarding, Abbreviated Dialing, etc., are becoming increasingly important toindividual subscribers for the added convenience they provide, as well as totelecommunications service providers as sources of additional revenue. Such servicesare generally provided by special programming in the software of the central officeexchange serving a particular subscriber. That is, the local exchange switch softwareis separately programmed to provide special service features to the subscribersconnected thereto. Often both the hardware and the software of an exchange must beupgraded in order to enable the provision of special subscriber functionality.When a call involves an interconnection between two parties connected todifferent exchanges, it is completed via a so-called transit or tandem exchange whichforms part of the network interconnecting individual central office switches to oneanother. In such cases, the transit exchange is totally transparent to the two parties ofthe call and simply provides a voice path between the two end ofiices. Any specialservice features invoked by either party has traditionally been provided by the endoffice to which that subscriber is connected, independently of the network connectionbetween the two parties.In most telecommunications systems providing Plain Old Telephone Service(POTS), the communications link between a calling party (A—Party) and the called party(B-Party) is under the control of the A-Party. Consequently, the communications linkbetween the A—Party and the B-Party remains in place until the A-Party’s telephoneinstrument is placed “on-hook” in which case the system breaks the communicationslink and the end offices of both parties and in any transit exchange’s which have beenused to link the end offices together. If the B-Party were to place his or her telephoneinstrument on-hook, it has little effect until alter a period of the order of severalminutes when a timer triggers the disconnection of the circuits between the calling andthe called parties. In newer types of telecommunications services, such as theIntegrated Services Digital Network (ISDN), B-Party disconnect is employed but the1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-3-mechanisms for implementing it are considerably different from those of conventionalPOTS networks.Providing special subscriber services within conventional telecommunicationsexchange requires an extensive upgrading of the software of each and every individualexchange which is to furnish such special services to its customers. Such upgrading ofexchanges is often extremely expensive and virtually prohibitive from a cost-effectiveness standpoint with regard to the additional revenue provided by theadditional subscriber services. This observation is even more true in small towns orrural areas where the demand for special subscriber services is relatively low and whereexisting exchanges have been in place for a considerable period of time and continueto adequately serve the basic telecommunications needs of a majority of the subscribersin that area.The telecommunications business is facing increasing competitive pressures.The per-minute revenues of telecommunications operators everywhere has beensteadily decreasing due to a number of factors. The deregulation oftelecommunications services has increased the number of competitors in the business.Further, innovations like callback services and calling cards permit users to arbitragedifferences in bilateral calling rates between country pairs. Also, cable televisioncompanies have now started offering telephone services over their cable networks.Finally, innovative software has now made high-quality fu1l—duplex calls over theInternet feasible.Improvements in technology have also reduced the cost of providing basictelephone service. The telecommunications companies can no longer justify therelatively high tan'fi's levied on the provision of basic telephone services. Improvementsin technology have lowered the actual cost of delivering a telephone call to virtuallynothing. In economic terms, basic telephone services can be viewed as zero marginalcost business. The advances that have increased the power to price performance ratioof desktop computers over the years have also boosted the reliability and efficiency ofmodern telephone exchanges.The same situation obtains on interexchange connections also. Due to the useof optical fibre, a substantial amount of capacity has been added to the telephone1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-4-networks. Bandwidth no longer appears to be the scarce resource that it was just a fewyears ago, and, in fact has become a commodity that is frequently bought and sold inwholesale quantities.Improvements in technology have also reduced or eliminated the efiects of thegeographic distance between a calling party and a called party as a significant factor inthe cost of providing a telephone call. It has been argued that it cost no more in termsof network resources to call from Stockholm to Dallas (a distance of about 8,000kilometers) than it does to call from Dallas to Austin (a distance of about 300kilometers).The explosive growth of the Internet has largely been due to the exploitationof the fact that its basic TCP/IP protocol permits e-mail messages to be sent and filetransfers to be effected independent of the transmission distances involved.In spite of the fact that the provision of long distance services does not costmuch more than that of local basic telephone services, telecommunications operatorscontinue to charge more for long distance telephone calls than for local calls. Theincrease in competition in the telecommunications industry is likely to make thatsituation increasingly unsustainable. Since long distance calls have traditionally beena significant source of the operating profits of the telecommunications companies, it hasbecome increasingly obvious that the telecommunications companies need to find newsources of revenue.One way in which telecommunications operators can increase revenues is byoffering subscribers advanced services for which the subscribers would be willing topay a premium for. As described earlier, in the network architectures of the past, theadditional of new fimctionality to a network required that core exchange software berewritten -- an expensive and lengthy process that also carried the additional risk ofintroducing new bugs into the system. Furthermore, each exchange in the network hasto be updated with the new software which further increased the cost of introducingnew services. Telecommunications operators are no longer willing to tolerate such astate of affairs. There are great business opportunities for a telecommunicationsequipment manufacturer who can bring a product to the market first.CA 02264252 1999-02-22W0 98/09454 PCT/SE97/01370-5-Telecommunications operators have expressed a need for faster and lessexpensive techniques for the introduction of new services into their telecommunicationsnetwork. Further, they have desired that the impact of the new functionality be limitedto one or a few exchanges only. It has also been found desirable for service-5 administration tasks such as the installation or modification of services, the addition ofcustomer-specific data, etc., be capable of being handled from a central managementfacility.It has also been desired that the design and implementation of the new servicesbe done by the telecommunications operators rather than the equipment manufacturer.10 This would allow telecommunications operators to quickly react to perceived marketneeds and serve their customers more effectively and efficiently. It has also been founddesirable to incorporate greater intelligence in the exchange software to permit variousservices to interact with subscribers. In this manner, the telephone instrument canbecome an advanced interface to the telecommunications network.15 The Intelligent Network (IN) has been proposed as a solution to address theabove requirements. The IN technology is designed to allow a telecommunicationsoperator to design its own set of unique services or to adapt existing services tospecific customer requirements. Further, the IN architecture permits the impact ofinstallation of new services to be limited to a few control nodes.20 Another design feature of the IN architecture is its centralized administrationof services. This improves the response time and decreases the human resourceoverhead required to run the network. Furthermore, the IN architecture permitscustomer control of some customer-specific data.For example, some telecommunications operators offer "personal number"25 services. The personal number service involves giving each subscriber a specifictelephone number, usually one prefixed with an "area code" of 500. The designphilosophy behind the personal number service is to supplant the plethora of contactnumbers for each subscriber with just one phone number. Thus, when someone dialsa subscriber's personal number, the exchange switch will query a central database and30 obtain a list of all of the telephone numbers where the subscriber might possibly be 1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-5-reached. The switch will then ring each of those numbers in a predetermined orderuntil the call gets answered.In one variant of this service, a subscriber may be provided the ability todynamically update the contact number database from any telephone instrument. Suchcustomer control can permit a subscriber to add the number of a hotel or other locationwhere he or she may be temporarily located.The design philosophy behind the IN architecture is to reduce the time tomarket for the provision of new services, to lower development and administrationcosts, and to enhance profits deriving from the provision of premium services. Theclassic example of an IN service is the use of a single dialed number (the B-number) bycustomers spanning a large geographic area that is redirected to one of a plurality oflocal service centers. Thus, a pizza franchise can advertise a single telephone numberfor ordering pizzas. Whenever a customer dials the advertised number, the IN servicecan direct the call to the nearest franchisee based upon the number of the dialingsubscriber (the A-number).A Brief History of INThe Intelligent Network concept originated in the United States. Originally, theintent was to provide a central database for translating a single dialed number into adifferent terminating number. One of the earliest applications of IN services was toprovide toll free calling ("Freephone").Toll free numbers do not directly correspond to a physical telephone line, butneed to be translated into an actual termination number. The translation may bedependent upon the location of the caller and upon the time of day.A new signaling system called Signaling System No. 7 (SS7) was developed toallow high-speed communications between telephone exchanges before and during callsetup. The SS7 protocol allowed for the first time, the fast database lookups neededfor the implementation of toll—free calling. After the development of the SS7technology, it became possible to exchange data across a telephone network virtuallyinstantaneously. This was the genesis of the Intelligent Network.1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97I0l370-7-The next step in the revolution of the IN was to move from static databases todynamic ones that permitted customer control of customer-specific data. Additionalinteractivity came to be permitted when subscribers could control the progress of thecall by keypad interaction from the subscriber’s instrument. Such interactive IN isreferred to in the U.S. as the Advanced Intelligent Network (AIN).Present development and interest in the IN architecture is being driven by a fewlarge—scale applications. Two such applications are the Universal Personal Number(UPN) Service and Virtual Private Network (VPN) Service. In the UPN service, aunique number is assigned to each individual rather than to a telephone instrument.The UPN number can be used to reach a subscriber irrespective of his or her locationor type of network (whether fixed or mobile).The VPN service allows a private network to be constructed using publicnetwork resources. Thus, a corporation could have a corporate telephone network thatpermits all of its employees to communicate with each other without investing in thehardware or sofiware needed for providing a physical private network. Byimplementing a VPN service using the public network, a corporate customer can alsoavoid the costs of maintaining a physical network.Inadequacies of Present IN SystemsThe use of the Intelligent Network (IN) architecture has been advocated as asolution for speeding up the incorporation and roll out of new network capabilities andnetwork services. However, the presently articulated standards for implementing INconcepts suffer from a number of shortcomings.For example, in the Global System for Mobile Communication (GSM), amessage service called the Short Message Service (SMS) has been specified. The SMSservice enables short text messages to be sent to and from various mobile stations(MSs). An SMS message to a mobile station is always sent from an SMS ServiceCenter (SMSC). If an SMS message cannot be delivered to a subscriber because thesubscriber's mobile station is inactive or unable to receive SMS messages due to lackof memory, then the Home Location Register (HLR) associated with a Mobile1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-3-Switching Center (MSC) creates a Message Waiting Data List (MWD-List) to storesuch undelivered messages.When a subscriber activates his mobile unit, the HLR is immediately notified.When the HLR detects that a previously inactive mobile station has become active, itimmediately alerts the SMSC that had earlier tried to send an SMS message to theinactive mobile station. Upon receiving this alert, the SMSC is triggered to retransmitSMS messages that could not be delivered earlier because the mobile station had beeninactive. Current implementation standards for IN do not have any mechanisms forproviding similar or equivalent functionality.If a telecommunications service provider were to be able to monitor the activitystatus of a mobile station, and generate a subscriber activity report to the ServiceControlled Function (SCP) of an IN, then the service provider would be able toterminate a larger fraction of communication attempts. Consequently, thetelecommunications service provider could earn greater revenues and also increaseresource utilization within its telecommunications network.Thus, it would be highly desirable to be able to provide some means within anIntelligent Network system, to monitor the activity status of a mobile subscriber andreport the same to the SCP. This in turn, requires a system and method for probing amobile station and generating a mailbox status report to the controlling entity (i.e. theSCP).SUMMARY OF THE INVENTIONTherefore it is a primary object of the present invention to permit the easydetection of renewed activity of a mobile subscriber in a PLMN system. Oneembodiment of the present invention is implemented in an IN (Intelligent Network)telecommunications system comprising a plurality of IPs (Intelligent Peripherals)connected to an SCP (Service Control Point) and PLMN Gateways over a network.In one embodiment of the present invention, the activity status of a mobilesubscriber in a PLMN system is determined initially. If the mobile subscriber is foundto be inactive, the PLMN system is armed remotely from the IN system to detect anyWO 98/094641015202530CA 02264252 1999-02-22PCT/SE97/01370-9-renewed activity by the mobile subscriber. The activity status of the PLMN mobilesubscriber is continuously monitored.When renewed activity of the PLMN mobile subscriber is detected, thesubscriber activity probe is triggered and an alert message is transmitted from thePLMN system to the IN system. This causes an internal report to be generated withinthe IN system that notifies the supervisory entity within the IN system to become awarethat the mobile subscriber is again active and can now be reached through the PLMNsystem.In another embodiment of the present invention, an SCP commands an SMS—IPto probe the activity status of a mobile subscriber. The SMS—IP in turn, sends a dummySMS message to a Gateway Mobile Service Center (GMSC) in the PLMN system thatis dedicated to handling SMS messages. Upon receiving the dummy SMS message, theSMS-GMSC activates the storage of non-delivered messages to a mobile subscriber byenabling the Message Waiting Data List (MWD-List) in the HLR of the mobilesubscriber. The SMS-GMSC also acknowledges the aiming of the PLMN to the SMS-IP. The SMS—IP in turn notifies the SCP that the “Send Probe” command has beensuccessfiilly executed.Upon the completion of these actions, the PLMN becomes armed. When apreviously inactive mobile subscriber becomes active, the notification of the renewedactivity to the HLR will result in the triggering and transmission of an “Alert”command from the PLMN to the SMS—IP. Upon receiving the alert from the SMS-GMSC, the SMS—IP unilaterally generates a “Mailbox Status Report” notification tothe SCP.BRIEF DESCRIPTION OF THE DRAWINGSA more complete understanding of the method and system of the presentinvention may be obtained by reference of the detailed description of the preferredembodiments that follow, taken in conjunction with the accompanying drawings,wherein:FIGURE 1 is an illustrative diagram showing the standard Intelligent Network(IN) Conceptual Model;1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370_1().FIGURE 2 shows the components of an exemplary simple Intelligent Network;FIGURE 3 shows the structure of a Service Independent Building Block (SIB);FIGURE 4 shows the mapping of the various IN fimctional entities into physicalunits;FIGURE 5 shows an example of an IN implementation with service nodes atthe transit level;FIGURE 6 shows the preferred methodology for implementing various servicesin the IN Conceptual Model;FIGURE 7 illustrates two approaches towards implementing an API;FIGURE 8 shows one technique for defining personal agents using ServiceLogic Programs (SLPS);FIGURE 9 shows the architecture of an exemplary mobile radiotelecommunications network;FIGURE 10 shows the operation of the Short Message Service (SMS) in amobile radio telecommunications system;FIGURE 1 1 shows one embodiment of the Networked IP (NIP) system andmethod of the present invention;FIGURE 12 is an overview sequence diagram illustrating the flow of messagesbetween the various logical entities of the present invention;FIGURE 13 is a sequence diagram illustrating the operation of the “MailboxStatus Report” command;FIGURE 14 is a sequence diagram illustrating the operation of the “MailboxStatus Enquiry” command when the SCP asks for brief information about mailboxstatus;FIGURE 15 is a sequence diagram illustrating the operation of the “MailboxStatus Enquiry” command when the SCP asks for detailed information about mailboxstatus;FIGURE 16 is a sequence diagram illustrating the operation of the “MailboxStatus Enquiry” command when a subscriber asks for brief information about mailboxstatus;1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-11-FIGURE 17 is a sequence diagram illustrating the operation of the “MailboxStatus Inquiry” command when a subscriber asks for detailed information aboutmailbox status;FIGURE 18 shows the sequence diagram when the SCP probes the activitystatus of a mobile subscriber;FIGURE 19 shows the finite state machine for the SCP during the operation ofthe present invention; andFIGURE 20 shows the finite state machine for the IP during the operation ofthe present invention.DESCRIPTION OF THE PREFERRED EMBODIMENTThe present invention provides a solution to one set of problems concerning thesupervision of the activity status of mobile subscribers whose terminal units are inactivewhen the delivery of messages originating outside a PLMN network (such as electronicmail (e-mail) messages or SMS (Short Message Service) messages) is first attempted.The extensions to the IN concept disclosed and described in this application can alsobe used in other telecommunications contexts and can also facilitate the provision ofrelated supplementary services to subscribers.Intelligent Network (IN) ArchitectureAn Intelligent Network is a telecommunications network architecture thatprovides flexibility for facilitating the introduction of new capabilities and services intoa network such as the Public Switched Telecommunications Network (PSTN) or aPublic Land Mobile Network (PLMN). Examples of such new capabilities and servicesinclude toll free calling (“Free Phone”), credit card services and Virtual PrivateNetworks (VPN).IN embodies the dreams of the unbundled network of the fiiture in whichfreedom is given to service providers and users to personalize the network services,independently of access, switch term technology and network providers. Aninternational consensus view on IN is described in the ITU-TS RecommendationQ1200.101520.2530CA 02264252 1999-02-22W0 93/09454 PCT/SE97l01370-12-The details of the IN architecture have been specified in the InternationalTelecommunications Union (ITU) Recommendation 1.3 12/Q. 1201 which also containsa verbal explanation of the IN Conceptual Model (INCM) shown in FIGURE 1. TheITU’s IN Conceptual Model analyzes and systematizes the various tasks and processesassociated with call handling and the provision of services into four planes: a ServicePlane 101, a Global Function Plane 102, a Distributed Function Plane 103, and aPhysical Plane 104.So far, IN has been concentrated around a group of services referred tohereafter as Number Services, for example, toll free calling (“Free Phone”), credit cardcalling, personal number services, televoting, etc. A key characteristic of all theseservices is that they provide service to numbers that are unbundled from the accessports in the access nodes. Any node in the telecommunications network can be madea service node by the addition of a Service Switching Function (SSF) and/or SpecialResource Function (SRF), both under control from a Service Control Function (SCF)via a service-independent protocol interface. The SCF is supported by a Service DataFunction (SDF), which may be physically unbundled from the node.The main building blocks of IN are the SSF, the SCF, the SDF and the SRF.The SRF is also referred to hereafter as the logical Intelligent Peripheral (logical IP).Each of these building blocks is a separate logical entity which may, but need not, bephysically integrated with the other entities of the telephone network, logical orotherwise. The physical and logical entities are referred to interchangeably as one inthe following description of the preferred embodiment.The IN architecture divides the basic call process into discrete strictly-definedstages that gives telecommunications service providers and subscribers the ability tomanipulate the call process. The components of a simple Intelligent Network 200 hasbeen shown in FIGURE 2. The standard architecture of the Intelligent Network hasdefined various components of the IN as well as the interfaces between the individualcomponents.When a call is made to an IN service, the call is first routed to a special nodein the network that is called the Service Switching Point (S SP). If the SSP recognizesan incoming call as an IN call, then all further processing of the call is suspended whilel0I5202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-13-the SSP informs the Service Control Point (SCP), another node in the IN system, thatan IN call has been received.The SCP provides the "intelligence" in the "Intelligent Network." The SCPcontrols everything that happens to an IN call and makes all the call processingdecisions. When the SCP decides upon the appropriate action that is to be performedon the call, the SCP instructs the SSP to carry out the necessary action.The Service Control Function (SCF) contains the logic of an IN service andbears the complete responsibility for making decisions related to a call invoking thatservice. This service logic may run on any telecommunications platform (e.g.,Ericsson's AXE platform or UNIX). The node (ie, the physical hardware and thesofiware) that contains the SCF is called the Service Control Point (SCP) 20].The data needed for each service (e.g., the list of subscriber telephone numbers)is provided by the Service Data Function (SDF). In one implementation of the INarchitecture, the data needed for the services is stored in the SCF itself. Formally, thefunction of storing the service-related data is allocated to the SDF which provides thedata upon demand to the SCF. In a typical IN implementation, the SDF can be UNIX'smachine running a commercially-available database program such as Sybase. Thephysical node that contains the SDF is referred to as the Service Data Point (SDP) 202.The normal call handling and supervisory fiinctions of an exchange areperformed by the Call Control Function (CCF). While the CCF is not formally part ofthe standard IN architecture, the CCF provides the IN with information about calls andalso executes orders that have been received by the SSF.The Service Switching Function (SSF) interprets the instructions sent by theSCF and passes the commands to be executed to the CCF. The SSF also receives callevent data (e.g., the onhook/oflhook status of a subscriber or a subscriber line beingbusy) from the CCF and passes the data to the SCF. The physical node (ie, theexchange hardware and software) that contains the SSF is referred to as the ServiceSwitching Point (SSP) 204 and 205.The Specialized Resource Function (SRF) provides certain resources for usein IN services, e. g., DTMF (Dual Tone Multiple Frequency) digit reception,announcements and speech recognition. In the ITU IN recommendations, the SRF1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-14-communicates directly with the SCF. In another implementation of the IN, the SRFfunctionality may be co-located with the SSF. In this case the SRF does notcommunicate directly with the SCF, but via the SSP. The SRF is not shown inFIGURE 2.The Service Management Function (SMF) 207 administers the maintenance ofIN services, e. g., the addition or removal of data or the installation or the revision ofservices. The Service Creation Environment Function (SCEF) 207 allows an INservice to be developed, tested and input to the SIVIF. In one implementation of the IN,the SMF and the SCEF are combined into one and termed the Service ManagementApplication System (SMAS). The SMAS application is part of the TMOS family andruns under the UNIX operating system. It permits services to be designed using agraphical interface and provides convenient forms for the entry of service data.FIGURE 2 shows an exemplary SCP 201 connected to an SDP 202 and SSPs204 and 205. The SCP is also connected to an SMF/SCEF 207. All of the linksrunning to and from the SCP 201 are shown as dashed lines in FIGURE 2 to indicatethat they are not voice links. The SDP 202 is also connected by a non-voice link to theSMF/SCEF 207. The SSP 204 is connected to two local exchanges (LE5) 223 and 224as well as to a transit exchange (TE) 211. The transit exchange 211 in turn isconnected to two other local exchanges 221 and 222. The SSP 205 is connected tolocal exchange 225. The local exchanges 223 and 224 are shown in FIGURE 2 to beconnected to an exemplary originating subscriber T-A 231 as well as to an exemplaryterminating subscriber T-B 232.If each of the logical building blocks of the IN are also physical entities, in thenotation described earlier, the corresponding physical nodes are called the ServiceSwitching Point (SSP), the Service Control Point (SCP), the Service Data Point (SDP),and the physical Intelligent Peripheral (IP). As stated earlier, in the discussion thatfollows, the term IP is used to generally refer to both a logical IP as well as a physicalIP.The user agent is identified in the SCF by the calling or the called party number,and invoked when an armed trigger point in the serving node is hit. Signaling data andcall state data can be manipulated by the user agent. The SRFs are capable of in-band1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-15-communication with the users or with each other to overcome limitations in the currentsignaling systems.Current IN standards assume that the visited location and the home location ofa subscriber are collocated but possibly unbundled from the access node and the servicenode. Although the separation of the access node and the service node functionsreduces service introduction costs, it results in potentially unwanted interactionsbetween access port services and number-based services. An enhancement of theaccess node to a service node is therefore required to provide flexibility in servicedesign.An alternative would be to add two remotely changeable personaltelecommunications categories to the access nodes —- one providing an unconditionalhot-line connection to the service node for originating calls, and the other giving anunconditional call forwarding to the service node for terminating calls. It appearsnecessary in the longer term to separate the visited and home location functions as incellular networks if costs are to be reduced and capacity is to be improved.One of the unique characteristic of IN is that services are implemented on theIN service platform based on its service independent building blocks (SIBS), and notdirectly in the network nodes. The SIBs are part of the SCP. FIGURE 3 shows thestructure of a SIB. Each SIB 301 is an elementary logical element in a service logicthat hides the implementation from the programmer. When existing SIBs cannot meeta new requirement, new SIBs are defined.In IN products, the SIBs 301 perform functions such as analysis of signalinginformation, control of connection topology, interaction with the user, reading andwriting of data, collection and output of call data, etc. Other SIBs are pure languageelements such as jump, go to subroutine, loop, handover, etc. Each SIB 301 isavailable in the service platform. Service Logic Programs (SLPs) are built by SIBs 301and refer to by their names. Service logic can be designed using a Service CreationEnvironment Function (SCEF). The SIBs 301 are made available to the SCEF througha system-independent Application Programming Interface (API).The mapping of the various IN functional entities into physical units or entitiesis shown in FIGURE 4 where the suflix stands for the various functional entities1015202530W0 98l09464CA 02264252 1999-02-22PCT/SE97/01370-16-and the suffix “P” stands for physical entities. In FIGURE 4, the acronym SMF refersto the Service Management Function and the acronym CCF refers to the Call ControlFunction.An example of an IN implementation with service nodes at the transit level isillustrated in FIGURE 5. The service nodes shown in FIGURE 5 can be reached fromany access node such as a local switch in PSTN or ISDN or an MSC in a Public LandMobile Network (PLMN) system. The service nodes can serve both personaltelephony as well as other number-based services. User identities and authenticationinformation may be transferred in-band to the SRF or embedded in calling- and called-party number fields in the signaling systems.The personal agent has components in the Call Control Function, CCF (ie., thetrigger point data), the Service Control Function, SCF (i.e., the service logic), and inthe Service Data Function, SDF (ie, the service data). The IN platform componentsillustrated in FIGURE 5 can be either integrated into the access nodes or implementedin separate service nodes.The role of the Service Switching Function (SSF) is to recognize that a call isinvoking an IN service, and then to communicate with the SCF to receive instructionsabout how to handle the call. The SCF is where the intelligence of the IN resides asit contains the logic required to execute various services. The SDF is a databasesystem that provides the data storage capacity needed for the data intensivesupplementary services. The IP is the network element that provides resources for userinteraction such as voice announcements and dialogue, dual tone multi—frequencyreception (DTMF) and voice recognition.The IN Application Programming Interface (API)The ITU’s IN Conceptual Model shown in FIGURE 1 also defines themethodology for implementing various services. This is shown in FIGURE 6. In orderto implement a service or feature 601, the service requirements are first translated toSIB structures at 602. The resulting SIBs 603 are mapped at 604 to various FunctionalEntities 605. The Functional Entities 605 in turn are mapped at 606 to one or morePhysical Entities 607.1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-17-It should be noted that unlike the practice with all non-IN standards, the servicerequirements in IN are not directly translated into network fimctionality. Instead, theservice requirements are translated into service platform elements (i.e., SIBs) which inturn are implemented according to the IN three-stage model to become reusablecapabilities and protocol elements in the telecommunications network.There are at least two possible approaches toward implementing theApplication Program Interface (API) that conform to the ITU’s IN Conceptual Modelshown in FIGURE 1. One approach would be to split the service logic into two parts:a fixed logic part and a flexible logic part. The SIBs are then linked to form decisiongraphs that are called as subroutines by the fixed logic. The fixed logic can beexpressed in a standard programming language such as C or C++, etc., and compiledand loaded into a standard execution environment. The flexible logic part, in contrast,consists only of exchangeable data.The second approach would be to define a service API that gives full controlover all aspects of the logic by combining SIBs with each other to achieve the desiredfunction. Each SIB can be linked to any other SIB in this approach. Some SIBsperform a telecommunications function while others are only linking elements in thelogic. All logic is expressed as data that describes which SIBs are to be used, how theyare linked, and what data each SIB is to use to perform its fimction. Allimplementation details are thus hidden from the service programmer. This is theprincipal approach taken in Ericsson’s IN products.The two approaches toward implementing the API are illustrated in FIGURE 7.The SH3-platform approach is shown in FIGURE 7A, and the Service Logic ExecutionEnvironment (SLEE) approach is shown in FIGURE 7B. The SIB approach ofFIGURE 7A expresses all service logic as a combination of elementary SIB functionsthat are available in the service platform to form flexible service profiles (FSPs). TheSLEE approach shown in FIGURE 7B considers the SIBs as subroutines to the fixedlogic expressed in a programming language such as C, C++, Service Logic Programs(SLPs), etc. The compiled code uses telecommunications platform primitives, such asINAP (Intelligent Network Application Part) operations and database primitives.l015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-13-When the same data representation is used for all logic and data, personalagents can be defined by means of Flexible Service Profiles (FSPs), as shown inFIGURE 8. This arrangement offers a number of advantages, for example, permittingdifferent logic elements to be loaded and activated without disrupting service, and incase of a fault in a personal agent, limiting the affected zone to only calls activating thefaulty function.Feature interaction has been a major obstacle in the development of IN systems.This problem arises from the fact that each feature is normally dependent on otherfeatures. There is a need to resolve such interactions, but no solution has yet beenagreed on. It has been found in practice that existing feature implementations are oftenaffected and many have to be redesigned or completely blocked when new features areintroduced. It should be noted that this problem can be approached from twoviewpoints: the network-centric view and the user-centric view of IN systems.The traditional network-centric view sees IN as a complement to othertechnologies in adding supplementary services to an existing repertoire. Featureinteraction has and continues to be the obstacle that prevents this view from being arealistic alternative. Each new supplementary service is composed of a fixed servicelogic part, and potentially of a flexible logic part. Personalization is thus limited towhat can be achieved by combining a number of pre-defined supplementary services orfeatures with each other. The addition of a new service may require long and costlydevelopment, not different from the pre-IN experiences in PSTN, PLMN and ISDN.The central issue in this viewpoint is not the design of a new feature, but on the taskof integrating a new feature with other preexisting features.In contrast, the user-centric view of IN focuses on the users rather than on thefeatures. In principle, the needs of individual users are assumed to be unique, with theservice provider being in fiill control of all service logic. The FSP approach is applied,and the result is that a range of unique service profiles can then be created by reusingSIBs rather than reusing features. This means that feature interaction ceases to be aproblem, since no individual features are implemented. The interaction between theSIBs constitutes the service logic in this approach.WO 98/09464l015202530CA 02264252 1999-02-22PCT/SE97/01370-19-Interaction between service profiles in this approach is resolved through opensignaling interfaces according to the half-call model. Before complete control can beprovided from the step—wise developed IN platforms in an economically feasible way,it has been found necessary to use some of the existing supplementary services. Itshould be borne in mind that this is a shortcut that can result in interaction problemsrequiring enhancement of the IN platform in the future.The principal goal in the user-centric view is to make the SIBs standardized soas to achieve both service—independence and system-independence and technology—independence. When this is achieved, a SIB—based service profile can be executed onany compatible platform, whether it is a switch processor, a stand-alone personalcomputer, or work-station. The old paradigm, giving the same features to allsubscribers, is replaced by feature transparency for each individual subscriber,irrespective of access.IN SignalingThe Intelligent Network Application Part (INAP) Protocol is used for signalingin IN systems. The INAP signaling protocol has been standardized by both theEuropean Telecommunications Standards Institute (ETSI) and the InternationalTelecommunications Union (ITU), and includes the CCITT Signaling System No. 7(CCS7) which is one, but not the only network protocol that may be used to supportINAP.One of the shortcomings of the core INAP as it is specified today (i.e., the INCS-1 standard), is that the communication possibilities between the SCF and the IPsare restricted to speech only. Other media such as e-mail, facsimile, data, etc. arecurrently not supported by the CS-1 standard. Thus, non-call-related and non-real timecall-related services are not included in the present CS-1 standard.The Networked IP (NIP) implementation, of which the present invention is apart, can be characterized as an extension to the INAP to include the handling andprocessing of non—voice media and the provision of non~ca1l-related communicationbetween the SCF and the IPs. NIP allows the SCF to be in total control of all store-and-forward ‘(i.e. messaging) services such as voice mail, e-mail, SMS messages, etc.1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-20-The protocol used for the NIP implementation is referred to hereafier as NIP-INAP.The NIP-INAP is an Ericsson-specific extension to the IN CS-1 standard.Cellular Network ArchitectureIn the second generation of standards for digital cellular telecommunicationssystems, e.g., GSM, Base Station Controllers (BSCs) act as access nodes. EachVisited Mobile Switching Centers (V-MSC) comprises hardware and software havingthe functionality of both a VLR as well as an MSC. Thus, each V-MSC can act as botha switching center as well as a visited location with transparent signaling to thecorresponding BSC.It should be noted that nodes in a GSM system have been standardized to suchan extent that new services and features cannot be added without violating (or at leastderogating from) the standard. In contrast, the standards governing nodes in an INsystem permit extensive customization.A separate location management mechanism has been developed to associateterminal identities with the geographical and physical addresses that may change whenthe terminals move. In GSM, each terminal receives its identity from a user's SIM cardinserted in the terminal, and bears no association with its physical location in thenetwork.An addressable entity called the Home Location Register (HLR) handles theterminal agent fiinctions for a partition of the terminal number series. The HLRintegrates a number of functions. For example, the HLR perfonns locationmanagement of the call managers to ensure that the flexible (or variable) portion of asubscriber’s service profiles are currently updated in every visited location where thefixed portions of the profile have been installed.The HLR also provides assistance in call set-up to the terminal by forwardingcall data to the VLR, and obtaining in retum, the Roaming Number (RN), which is thenused to set up the connection for the call through the PSTN. The RN is used onlyduring call set-up, to associate the terminal number with the connection, thuscircumventing the limitations of the PSTN signaling that permits it to carry only onecalled party number. The HLR also provides for direct communication with the1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370.2}.terminals (using the MAP protocol) to receive service management directives. The useof the personal SIM card unbundles the user from the terminal. However, currentstandards do not permit more than one user to be registered at any one terminal at agiven time.The supplementary services that are provided to subscribers have also beenstandardized in GSM. The majority of these supplementary services, especially thoseusing call state information, are implemented in the visited locations. Call forwardingservices are performed by the HLR. Use of the same standard by a large number ofoperators provides feature transparency for users over very large areas.GSM, for example, will cover all of Europe and several countries. The largenumber of competing operators and vendors involved make it difficult to arrive at aconsensus on additions, amendments or adaptation for personalization. Consequently,the provision of additional functionality and of supplementary services need to be doneoutside the GSM standard.FIGURE 9 shows the architecture of an exemplary mobile radiotelecommunications network. A cellular network comprises a terminal 903 into whicha subscriber 901 inserts a personal SIM card 902. The terminal communicates with aBase Station (BS) 904 over an air interface, such as an air interface specified in anexisting communication system. In an alternative implementation of the GSM system,the terminal 903 has an identity of its own that is built in by the manufacturer of theterminal.Registration and service management, as well as terminating call managementbased on user changeable data, are all performed in the Home Location Register (HLR)907. Originating call management and terminating call management based on terminalstatus are handled by the Visited Mobile Switching Center (VMSC) 906 that alsocontains the Visitor Location Register (VLR). The VMSC is (conceptually) both thevisited location as well as the serving node.Routing to a cellular terminal is made by using the Roaming Number (RN) thatis obtained using the signaling between the Gateway MSC (GMSC) and the VisitedMSC (VMSC) via the Home Location Register (HLR). The Mobile Application Part(MAP) signaling protocol is used for the signaling between the GMSC 908 and the1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-22-VMSC 906. It should be noted that the signaling between every GMSC and everyVMSC is performed through a HLR and not directly. The CCITT Signaling SystemNo. 7 Telephone User Part (TUP) and the CCITT Signaling System No. 7 IntegratedServices User Part (ISUP), shown as element 909 in FIGURE 9, connect the cellularsystem to the public telephone system gateway node. The Base Station 904 iscontrolled by the Base Station Controller (BSC) 905 that also serves as an access node.SMS Service in Cellular SystemsThe operation of the Short Message Service (SMS) in a cellular system isdepicted in FIGURE 10. The originator of a Short Message (SM) shown as MS-A1060 in FIGURE 10 sends a Mobile Originated Short Message (MO-SM) to a servicecontroller selected by MS-A 1060. The MO-SM is sent by issuing a “Forward SM”MAP command from the visited MSCNLR 1051 to the Interworking MSC (IWMSC)1052.The transmission 1071 from the MSC/VLR 1051 to the IWMSC 1052 isperformed by using the selected SC-A address as a “Global Title” as specified in theE. 164 standard. The IWMSC 1052 analyzes the SC-A address in the “Called Address”SCCP component, changes the translation type and forwards the MO-SM to SC-A1053 using the “Forward MO-SM” command in the SMS-MAP protocol, as shown at1072.When the Mobile Originated Short Message reaches the selected Service Center(SC-A) 1053, the SC-A executes one of a plurality of actions according to thedirections or preferences of the Mobile Subscriber A 1060. It should be noted that themobile subscriber's preferences need to be stored in the Service Center 1053 beforesuch preferences can be executed.In one embodiment of the present invention, the Service Center SC-A 1053 canperform a number of operations on the Mobile Originated Short Message. Examplesof such actions include duplication and storage of a received Short Message,retransmission of a Short Message based upon a distribution list defined by MS-A1060; conversion of an SM to a desired or preferred medium, etc. All of these actionscan be based‘ either on an indicated Protocol ID (PID) value or are based upon a1015202530CA 02264252 2005-02-04WO 98/09464 PCT/SE97/01370-23-subscriber defined profile value. These extensions to the standard functionality of a SMSsystem are described in greater detail in U.S. Patent, 6,108,559, entitled A SYSTEM ANDMETHOD FOR ROUTING MESSAGES IN RADIOCOMMUNICATION SYSTEMS,granted August 22"“, 2000, in the names of B0 AsrRoM and Roland BODIN.The SC-A 1053 can also distribute a Short Message to a subscriber-defineddistribution list afier converting the SM to one or more desired media according. Uponreceiving the Mobile Originated Short Message, the SC-A 1053 acknowledges the same to theIWMSC 1052 as shown in 1073. The IWMSC 1052 in turn acknowledges the successfulreception of the MO-SM using the MAP interface to the Visited MSC/V LR 1051. This isshown at 1074. The visited MSC/VLR 1051 then forwards the acknowledgment to MS—A1060.In one exemplary embodiment of the SMS system, the MO-SM is sent as a MobileTerminated Short Message (MT-SM.) to the Mobile Station B (MS-B) 1065. The stepsinvolved in this transmission are shown by arrows labeled 1075-1080 in FIGURE 10.First, the SC-A I053 sends an MT-SM using the SMS-MAP interface to a GatewayMSC handling SM messages (SMS-GMSC) 1054. The SMS-GMSC 1054 then sends a queryto the HLR 1055 to, determine the present location of the intended recipient of the ShortMessage. The query to the HLR is perfonned over the MAP interface using the “SendRouting Info for SM" command-In response to the query, the HLR 1055 returns inter alia an MSC number and theIMSI (International Mobile Subscriber Identity) to the SMS-GMSC 1054 as shown at 1077.The SMS-GMSC sends the MT—STM to the visited MSC/VLR 1056 using the “Forward SM”command. The visited MSC/VLR 1056 then delivers the MT-SM to the Mobile Subscriber B(MS-B) 1065 who acknowledges receipt to the visited MSC/VLR 1056.Upon receiving an acknowledgement from MS-B, the Visited MSC/VLR 1056generates an acknowledgement to the SMS-GMSC 1054 as shown at 1079 over theMAP interface using the “Return Result Component To Forward SM” message. The1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-24-delivery of the Mobile Terminated Short Message to the intended recipient MB-B 1065is acknowledged back to the SC—A 1053 as shown at 1080 by transmitting a “RetumResult Component To Forward MT-SM” confirmation message.Networked IPsFIGURE 11 shows one embodiment of the Networked IP (NIP) system of thepresent invention. A Networked IP system comprises an SCP 1101 that cancommunicate with a plurality of Intelligent Peripherals (IPs) 11 11-11 14. Each of theselogical IPs are SRFs in IN terminology, as noted earlier. For illustrative simplicity, onlyfour IPs are shown in FIGURE 11: IP1 1111, IP2 1112, IP3 1113 and an SMS-IP, IP,1114. The [P5 1111-1114 can communicate amongst each other over acommunications backbone 1110 using any protocol, for example, TCP/IP, X.25, etc.FIGURE 11 also provides an overview of the message flow and operation ofan embodiment of the present invention. As shown in FIGURE 11, the networked IPs1111-1114 interact with the Public Land Mobile Network (PLMN) 1150 through aGateway Mobile Services Switching Center (GMSC) 1161. As explained earlier inconjunction with the discussion of FIGURE 10, the GMSC 1161 can terminate an SMSmessage by polling a recipient’s Home Location Register (HLR) 1 166, ascertaining thecurrent location of a mobile subscriber 1165 and routing the SMS message through aVMSC 1162 and a Base Station Controller (BSC) 1163 and a Base Station (BS) 1164.The conjunctive operation of an IN system and a PLMN 1150 is illustrated inFIGURE 11. The process starts with an SCP 1101 commanding the SMS-IP 1114 toprobe the activity status of a mobile subscriber. This is done as shown at 1171 by a“Send Probe” command sent from the SCP to the IP,, the SMS-IP. In response, theSMS-IP 1114 sends a dummy SMS message to the Gateway MSC 1161 as shown atl 181 .It should be noted that the term "dummy SMS message" as used here can beany syntactically-accurate SMS message. The message is called a "dummy" messagebecause it doesn't have to contain any specific content. The dummy SMS message isthus akin to an empty envelope that is sent to an addressee for the purpose of verifyingthe existence___or accuracy of an address. The dummy SMS message is important for1015202530W0 98/09464CA 02264252 1999-02-22PCT/SE97/01370-25-what it does or causes (i.e., activation of the message waiting fiinction in a mobilesubscribers HLR, as explained below) rather than for what it contains. Thus, a dummySMS message can be a real SMS message with null contents, or even a defective SMSmessage that would be rejected by a mobile subscriber if it were active.Upon receiving the dummy SMS message, the GMSC 1161 activates thestorage of non-delivered messages to a mobile subscriber by enabling the MessageWaiting Data List (MWD-List). The GMSC also acknowledges the arming of thePLMN to the SMS-IP 1114 as shown at 1182. The SMS-IP 1114 in turn notifies theSCP 1101 at 1172 that the “Send Probe” command has been successfully executed.Upon the completion of the above actions, the PLMN 1150 has now beenarmed. When a previously inactive mobile subscriber becomes active, the notificationof the renewed activity to HLR 1166 will now result in the triggering of an “Alert”command from the PLMN 1150 to the SMS-IP as shown at 1183. Upon receiving thealert from the GMSC 1161, the SMS-IP 1114 unilaterally generates a “Mailbox StatusReport” notification to the SCP 1101 as shown at 1173.FIGURE 12 is a sequence diagram illustrating the flow of messages betweenthe various logical entities of the present invention. As shown in FIGURE 12, thesubscriber activity monitoring process comprises two phases. In the first phase, upona probed mobile subscriber not being active, the IN system components arm the PLMNsystem to generate an activity alert. In the second phase, the PLMN generates an alertto the SMS-IP when an erstwhile inactive mobile subscriber becomes active in turngenerating a “Mailbox Status Report” to its controlling SCP.The communications between the SCP and the various IPs 1111-1114 is shownusing Transaction Capabilities Application Part (TCAP) notation in FIGURE 12, withthe message type being shown above the arrow and the components of the TCAPmessage and the parameters being shown beneath each arrow.The process begins when an SCP attempts a dial-out and fails. Thus, in the firstphase, upon receiving a “Send Probe Message” command from the SCP 1101 as shownat 1201, the SMS-IP 1114 in turn issues a “Probe SMS Sending” command at 1202 tothe PLMN system 1150. This causes a flag to be activated in the queried recipient's1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-26-HLR to indicate that the queried SMS-IP is to be notified when the mobile subscribernext becomes active.Simultaneously, the PLMN system 1150 activates the storage of undeliveredmessages to the subscriber by enabling the MWD-List. The PLMN then notifies theSMS-IP 1114 by sending a “Message Waiting Set In PLMN” acknowledgment to theSMS-IP at 1203. This in turn is acknowledged by the SMS-IP 1114 back to the SCP1101 at 1204. The probe here is an SMS message which makes use of the “MessageWaiting” feature of PLMN system that can create a MWD-List in the HLR to retainundelivered messages.In the second phase, the PLMN triggering notification phase, the PLMN 1205issues an “Alert” notice to the SMS-IP 1114 at 1205. The SMS-IP 1114 in turngenerates a “Mailbox Status Report” notification to the SCP 1101 as indicated at 1206.Afier this notification is received, all fiirther action by the SCP is at its own discretion.An IN service provider may wish to generate a subscriber activity report. Sucha feature would permit an SCP to determine whether a specific mobile station isswitched on or not. A subscriber activity report of this kind would be particularlyusefiil, for example, if a dial-out notification fails due to a desired mobile station beingdetached or out of memory. In such a case, it would be usefiil for the SCP to be ableto monitor the activity of the mobile station in order to detect when the mobile stationbecomes reachable again.As detailed earlier, the architecture of a standard cellular system presentlyincludes a facility that causes the Home Location Register (HLR) to create a messagewaiting date list (MWD-List) if an SMS message cannot be delivered to a mobilesubscriber. Consequently, it would be useful if this pre-existing feature of the cellularsystem can be utilized to solve the need to automatically generate a subscriber activityreport.Mailboxes can exist for several different media, for example, voice mail,facsimile mail, e-mail, SMS, etc. In the present disclosure, each medium and itsassociated mailbox, is referred to as a logical IP. In order to control the messagesreceived by a subscriber in his mailbox, and to facilitate the notification to the SCP orWO 98/094641015202530CA 02264252 1999-02-22PCT/SE97/01370-27-the subscriber when the status of a subscriber's mailboxichanges, it would be usefirl foran SCP to be informed about the status of a subscriber's mailboxes.The present invention provides a solution for monitoring the activity of mobilesubscribers, and consequently, to notify an SCP when renewed subscriber activity isdetected. The present invention does this by introducing two new procedures to theNIP-INAP: the “Send Probe” command which enables an SCP to order an SMS—IPto send a dummy SMS message to a mobile station in a PLMN system; and the“Mailbox Status Report” command which enables an IP to report to the SCP when thestatus of a specific mailbox has changed.Presently, an IN node is generally unable to monitor an unreachable mobilestation. The present invention provides a networked solution based on the INarchitecture by defining a protocol to enhance service revenues by increasing thesuccessful message delivery rates.Another aspect of the present invention enables an SCP to be updated about thestatus of a subscriber’s mailboxes. Two new procedures have been introduced to theNIP-INAP for this purpose: the “Mailbox Status Report” command which enables anIP to notify an SCP when the status of a specific mailbox has changed; and the“Mailbox Status Enquiry” command which enables an SCP to poll or query an IP aboutthe status of a particular subscriber mailbox.Extensions to NIP-INAP ProceduresWe will next consider the detailed operation of the various new procedures thatare introduced to the NIP-INAP for the implementation of the preferred embodimentof the present invention. Before an SCP can order an IP to query the activity status ofa mobile subscriber in a PLMN system, procedures are necessary to facilitate thenotification of the SCP when an alert message has been received by an SMS—IP froma PLMN system.The “Mailbox Status Report” MessageThe spontaneous report by an IP of the change in mailbox status of a subscriberis implemented by using the “Mailbox Status Report” command. As shown in1015202530WO 98/09464CA 02264252 1999-02-22PCTISE97/01370_2g-FIGURE 13, the Mailbox Status Report is sent from an SMS-IP, IP, 1114 to the SCP1101 upon any change of mailbox status as long as the change in status was notinitiated or controlled by the SCP. However, when a message is deposited in a mailbox(i.e., it is received by the IP designated for receiving messages in a certain medium), theSMS-IP generates a “Mailbox Status Report” message even if the SCP is in control.In the discussion that follows, the role of the SMS-IP can be played by any of the otherNetworked IPs 1111-1113.It should be noted that at the time of issuance of this notification by theSMS-IP, IP, 1114, there may or may not be an ongoing dialogue between SCP 1101and IP, 1114. In order for the [PS 1114 to issue the “Mailbox Status Report” messageto the SCP, the status of a subscriber’s mailbox must change. Afier receipt of thiscommand by the SCP 1101, further action is at the discretion of the SCP.If desired, the SCP may obtain detailed information about the status of variousmessages using the “Mailbox Status Enquiry” command that is discussed below.Although the “Mailbox Status Enquiry” command is not essential to the operation ofthe preferred embodiment of the present invention, it is discussed below for the sakeof completeness.The “Mailbox Status Enquiry” MessageIn contrast to the “Mailbox Status Report” message, which is spontaneouslygenerated by an IP upon any change in mailbox status, the “Mailbox Status Enquiry”message is triggered only by affirmative action by the SCP or upon aflirmativesubscriber Enquiry about the status of his or her mailbox. FIGURES 14 and 15 showthe sequence diagram when an SCP enquiries an IP about the status of a subscriber’smailbox. If IP, 1114 has reported a change in mailbox status to SCP 1101 using the“Mailbox Status Report” message discussed earlier, and if the SCP 1101 desires toobtain more or detailed information about a subscriber’s mailbox or mailboxes, thereare two possible outcomes, as shown in FIGURES 14 and 15.If the SCP 1101 asks IP, 1114 for brief information about mailbox status, asshown at 1401, then IP, 1114 can return the desired result to SCP 1101 as shown at1402 without segmentation of the results. Likewise, if the SCP 1101 queries IP, 11141015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-29-for detailed information about mailbox status, and if no detailed information isavailable, then too the IP, 1114 returns the result in a unitary (i.e. unsegmented)message to SCP 1101 as shown at 1402.On the other hand, if the SCP 1101 queries IPS 1114 for detailed informationabout mailbox status, and if such information is available, then IP, 1114 sends theinformation to SCP 1101 in multiple segments, as shown in FIGURE 15. The processstarts with the SCP making a detailed enquiry of the IP, 1 1 14 at 1501. In response, IP,11 14 sends part of the results to the SCP at 1502. Thereupon the SCP asks for theremaining information at 1503. IP, provides another standard Return Result segmentat 1504 and (optionally) indicates that still more information remains available.This process is successively repeated with the SCP 1101 asking for more andmore information from IP, as indicated at 1505 until IP ,returns a Return Resultcomponent to the SCP as shown at 1506, indicating that no further information aboutmailbox status is available. When the SCP has obtained, assembled and analyzed thevarious segments of the result returned by IP,, all further action on its part is at its owndiscretion.In another embodiment of the present invention, the SCP may send a messageto a particular recipient, or notify a mailbox owner of the results of the “Mailbox StatusEnquiry” command on his mailbox.The “Mailbox Status Enquiry” command can also be used to service asubscriber who enquires about the status of his or her mailbox or mailboxes. This isillustrated in FIGURE 16 for the case when the returned result is not segmented, andin FIGURE 17, when the returned result is segmented.As depicted in FIGURE 16, when a user wants to know the status of hismailbox, the SCP issues a “Mailbox Status Enquiry” command as shown at 1602 to IP,1114 asking for brief or detailed information as appropriate. If only brief informationwas asked for at 1601, or if detailed information was asked but was not available, IP,1114 returns the result of the enquiry to the SCP as shown at 1602 withoutsegmentation of the results. Thereafter, further action is at the discretion of the SCP1101.1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-30-FIGURE 17 shows a sequence diagram when a user makes a detailed enquiryabout the status of his mailbox. Upon receiving the enquiry, SCP 1101 issues a“Mailbox Status Enquiry” command to [P5 1114, as shown at 1701, asking for detailedinformation about a particular mailbox or mailboxes. IPS ll 14 segments the results tobe returned, and sends the first segment back to the SCP as shown at 1702 andindicates that more information remains available. In response, the SCP invokes the“Mailbox Status Enquiry” command a second time at 1703 asking for some or part ofthe remaining information. The IPS 1114 responds by returning the second resultcomponent to the SCP as shown at 1704 indicating that there is still more informationavailable.As discussed earlier in connection with the description of the sequence diagramshown in FIGURE 15, the SCP 1101 repeatedly issues the “Mailbox Status Enquiry”command to [P5 1114 as shown at 1705 until 1P S1114 transmits a Return Resultcomponent as shown at 1706 indicating that no more information is available. TheSCP then assembles and analyzes the segmented result components returned andperforms fiirther actions at its own discretion.The “Mailbox Status Report” and “Mailbox Status Enquiry” commands makeit possible to initiate an alert to the SCP or to a subscriber when the status of thesubscriber's mailbox has changed and to centrally control all of a subscriber’s differenttypes of mailboxes despite the fact that they are located at physically and/or logicallydistinct IPs.We next consider the Subscriber Activity Supervision Service in further detail.Automating the monitoring and third-party notification of renewed activity bysubscribers in a PLMN system has long been desired by subscribers andtelecommunications service providers. As indicated earlier, there are no procedureswithin the presently defined IN architecture to monitor an inactive or unreachablemobile station.The present invention permits an SCP to monitor the activity of a presently-quiescent mobile station by introducing two new procedures: the “Send Probe”command which enables an SCP to order an SMS-IP to probe the activity status of a1015202530WO 98/09464CA 02264252 1999-02-22PCT/SE97/01370-31-mobile subscriber in a PLMN and the “Mailbox Status Report” notification whichenables an SCP to be notified when a subscriber's mailbox status changes.In the sequence diagrams presented below, a specific IP IPS 11 14, referred toas the SMS-IP, is used for the exchange of messages between an IN node and a PLMNsubscriber. However, it should be emphasized that the actual exchange can take placefrom an SMS-IP, from any IP supporting SMS messages, or from any other IPcontaining the necessary processing power and system resources.The “Send Probe” CommandFIGURE 18 shows the sequence diagram when the SCP probes the activitystatus of a mobile subscriber. As indicated here, the “Send Probe” command makesuse of the pre-existing feature in second-generation PLMN systems that causes theHome Location Register (HLR) in the PLMN to create a Message Waiting Data List(MWD-List) whenever a message cannot be delivered to a subscriber.When an MS is found to be unreachable, the process begins as shown at 1851with the SCP 1101 issuing a “Send Probe” message to an SMS-IP 1114. The SMS-IP1114 in turn sends a dummy SMS message to the unreachable MS in the PLMN 1150,as shown at 1852. Since the MS is unreachable, the HLR corresponding to the MS inthe PLMN 1150 creates an MWD-List for the recipient of the dummy SMS message.The PLMN, acting through the SMS Gateway MSC, acknowledges theactivation of the MWD-List to the SMS-IP 1115 as shown at 1853. This report ofsuccessful completion is forwarded in an appropriate format by the SMS-IP 1114 tothe SCP 1101 as shown at 1854.As detailed earlier, upon the MS becoming reachable, an alert is generated bythe PLMN 1150 to the SMS-IP 1114 causing the SMS-IP to issue a “Mailbox StatusReport” message to the SCP 1101.SCP and IP Finite State MachinesFIGURES 19 and 20 show the finite state machines for the SCP 1101 and theSMS-IP 1114 of the present invention. In FIGURES 19 and 20, the states of themachine are symbolized with an oval, while events causing state transitions are drawn1015202530CA 02264252 1999-02-22WO 98/09464 PCT/SE97/01370-32-by continuous arrows. Functions are depicted within broken rectangles, while actionsordered by the fimctions are indicated by broken arrows.FIGURE 19 shows the finite state machine for the SCP. As can be seen, theSCP has two states: the Idle state 1901 and the Active state 1902. The SCP goesfrom the Idle state 1901 to the Active state 1902 upon issuing a “Send Probe”command to the SMS-IP 1114, as shown at 1911.The SCP goes from the Active state 1902 to the Idle state 1901 as shown at1912 upon normal termination of the dialogue between the SCP and the IPs, if adialogue were rejected due to the presence of improper components, if a dialogue isaborted from either side or if the operation is timed out. The SCP 1101 loops (i.e.remains) in the Active state 1902 without any state transition as shown at 1913 uponthe receipt of the results of the “Send Probe” message from the SMS-IP 1114.FIGURE 20 shows the finite state machine from the IP side. The SMS-IP hastwo principal states: the Idle state 2001 and the Active state 2002. There is also oneadditional quasi-state: the PLMN Probe Handling state 2021.As shown in FIGURE 20, the SMS-IP 1114 goes from Idle state 2001 to theActive state 2002 upon receiving the “Send Probe” command from the SCP 1101, asshown at 201 1. An IP transitions from the Active state 2002 to the Idle state 2001 asshown at 2012 upon normal termination of the dialogue with the SCP or upon rejectionof an offered result by the SCP or upon an abort of the dialogue between an SCP andIP from either side.If an SMS-IP 1114 receives the “Send Probe” command, the transition from theIdle state 2001 to the Active state 2002 is additionally accompanied by the transmissionof the Mobile Terminated Probe Message to the PLMN probe handler as shown at2013 and the return of the results of the same as shown at 2014. The SMS-IP loops(i.e_ remains) in the Active state 2002 upon returning the results of the “Send Probe”message back to the SCP as shown at 2015.Although a preferred embodiment of the method and apparatus of the presentinvention has been illustrated in the accompanying drawings and described in theforegoing detailed description, it is to be understood that the invention is not limitedto the embodiment(s) disclosed, but is capable of numerous rearrangements,CA 02264252 1999-02-22W0 98/09464 PCT/SE97/01370-33-modifications and substitutions without departing from the spirit of the invention as setforth and defined by the following claims.

Claims (26)

WHAT IS CLAIMED IS:

1. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
sending a dummy SMS message to said mobile subscriber to determine an initial activity status of said mobile subscriber;
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring; and generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system

2. The method of Claim 1 wherein said step of arming said PLMN system comprises the step of conditionally activating a trigger function in said PLMN
system.

3. The method of Claim 2 wherein said step of conditionally activating a trigger function in said PLMN system is implemented by creating a Message Waiting Data List (MWD-List) in a Home Location Register (HLR) of the mobile subscriber in the PLMN system.

4. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;
sending a dummy SMS message from said IN system to said PLMN
system;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring; and generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system.

5. The method of Claim 4 wherein said dummy SMS message sent during said step of sending a dummy SMS message is sent from an SMS-IP to an SMS-GMSC, the SMS-IP being a specialized Intelligent Peripheral in the IN system that is dedicated to handling SMS messages, and the SMS-GMSC being a Gateway Mobile Service Center in the PLMN system that is dedicated to handling SMS messages.

6. The method of Claim 5 wherein the dummy SMS message sent during said step of sending from the SMS-IP to the SMS-GMSC is sent under the control of the SCP of the IN system, the SMS-IP being a specialized Intelligent Peripheral in the IN system that is dedicated to handling SMS messages, and said SMS-GMSC being a Gateway Mobile Service Center in the PLMN system that is dedicated to handling SMS messages.

7. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring;
generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system; and sending an acknowledgment from an SMS-GMSC to an SMS-IP when the remote arming of the PLMN system has been completed, the SMS-GMSC being a Gateway Mobile Service Center in the PLMN system that is dedicated to handling SMS messages, and the SMS-IP being a specialized Intelligent Peripheral in the IN
system that is dedicated to handling SMS messages.

8. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;

transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring;
generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system; and wherein the alert message transmitted during said step of transmitting is sent from an SMS-GMSC to an SMS-IP, the SMS-GMSC being a Gateway Mobile Service Center in the PLMN system that is dedicated to handling SMS messages, and the SMS-IP being a specialized Intelligent Peripheral in the IN system that is dedicated to handling SMS messages.

9. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring;
generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system; and sending a predetermined message from an SMS-IP to the SCP of the IN system, the SMS-IP being a specialized Intelligent Peripheral in the IN
system that is dedicated to handling SMS messages.

10. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
sending a dummy SMS message to said mobile subscriber to determine an initial activity status of said mobile subscriber;
arming said PLMN system from said IN system using a SEND PROBE
command to detect renewed activity by said mobile subscriber;
monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring; and generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN system.

11. In a method for indicating actively of an initially-inactive mobile subscriber operable in a PLMN (Public Land Mobile Network) system, an improvement of a method for indicating at least a change in the activity of the mobile subscriber from an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, the IN system coupled to the PLMN system, said method comprising the steps of:
sending a dummy SMS message to said mobile subscriber to determine an initial activity status of said mobile subscriber;
arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber;

monitoring at least during selected periods, the activity status of said mobile subscriber in said PLMN system;
transmitting an alert message from said PLMN system to said IN
system when renewed activity of the mobile subscriber in said PLMN system is detected during said step of monitoring; and generating an internal notification within said IN system using a MAILBOX STATUS REPORT command in response to the receipt of said alert message from said PLMN system to said IN system.

12. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for sending a dummy SMS message to said mobile subscriber;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected; and means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system.

13. The mobile subscriber activity supervision system of Claim 12 wherein said means for remotely arming said PLMN system additionally comprises means for conditionally activating a trigger function in said PLMN system.

14. The mobile subscriber activity supervision system of Claim 13 wherein said means for conditionally activating a trigger function in said PLMN system additionally comprises means for creating a Message Waiting Data List (MWD-List) in a Home Location Register (HLR) of the mobile subscriber in the PLMN system.

15. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for sending a dummy SMS message from said IN system to said PLMN system;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected; and means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system.

16. The mobile subscriber activity supervision system of Claim 15 wherein said dummy SMS message is sent from an SMS-IP to an SMS-GMSC, said SMS-IP
being a specialized Intelligent Peripheral in said IN system that is dedicated to handling SMS messages, and said SMS-GMSC being a Gateway Mobile Service Center in said PLMN system that is dedicated to handling SMS messages.

17. The mobile subscriber activity supervision system of Claim 16 wherein the transmission of a dummy SMS message from said SMS-IP to said SMS-GMSC
is performed under the control of the SCP of said IN system, said SMS-IP being a specialized Intelligent Peripheral in said IN system that is dedicated to handling SMS
messages, and said SMS-GMSC being a Gateway Mobile Service Center in said PLMN system that is dedicated to handling SMS messages.

18. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected;
means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system; and means for sending an acknowledgment from an SMS-GMSC to an S1VIS-IP when the remote arming of the PLMN system has been completed, said SMS-GMSC being a Gateway Mobile Service Center in said PLMN system that is dedicated to handling SMS messages, and said SMS-IP being a specialized Intelligent Peripheral in said IN system that is dedicated to handling SMS messages.

19. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected;
means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system; and wherein said transmitted alert message is sent from an SMS-GMSC to an SMS-IP, said SMS-GMSC being a Gateway Mobile Service Center in said PLMN
system that is dedicated to handling SMS messages, and said SMS-IP being a specialized Intelligent Peripheral in said IN system that is dedicated to handling SMS
messages.

20. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected;
means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system; and means for sending a predetermined message from an SMS-IP to the SCP of the IN system, said SMS-IP being a specialized Intelligent Peripheral in said IN system that is dedicated to handling SMS messages.

21. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for sending a dummy SMS message to said mobile subscriber;

means for remotely arming said PLMN system from said IN system using a SEND PROBE command to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected; and means for generating an internal notification within said IN system in response to the receipt of said alert message from said PLMN system to said IN
system.

22. In an IN (Intelligent Network) telecommunications system comprising a plurality of IPs (Intelligent Peripherals) connected to an SCP (Service Control Point) over a network, said IN system being further connected to a PLMN (Public Land Mobile Network) system, a system for monitoring the activity of a mobile subscriber in the PLMN, said system comprising:
means for determining an initial activity status of a mobile subscriber in said PLMN system;
means for sending a dummy SMS message to said mobile subscriber;
means for remotely arming said PLMN system from said IN system to detect renewed activity by said mobile subscriber responsive to a determination that said mobile subscriber is presently inactive;
means for continuously monitoring the activity status of said mobile subscriber in said PLMN system;
means for triggering and transmitting an alert message from said PLMN
system to said IN system when renewed activity of the mobile subscriber in said PLMN system is detected; and means for generating an internal notification within said IN system using a MAILBOX STATUS REPORT command in response to the receipt of said alert message from said PLMN system to said IN system.

23. In an IN (Intelligent Network), apparatus for indicating at least an activity-status change of an initially-inactive mobile subscriber operable in a PLMN
(Public Land Mobile Network), the PLMN coupled to the IN, said apparatus comprising:
a SCP (Service Control Point) for controlling initiation of monitoring of the mobile subscriber and for receiving indications of the change in status of the initially-inactive mobile subscriber;
an SMS-IP (Short Message Service-Intelligent Peripheral) coupled to said SCP and to the PLMN, said SMS-IP for initiating arming of the PLMN to detect renewed activity of the mobile subscriber, for receiving an alert from the PLMN
alerting said SMS-IP of the change in status, and for providing said SCP with the indications of the change in the status of the mobile subscriber; and wherein said SCP initiates the monitoring of the mobile subscriber by issuing a SEND PROBE command to said SMS-IP.

24. The apparatus of claim 23 wherein said SMS-IP is operable responsive to reception of the SEND PROBE command to initiate the arming of the PLMN.

25. The apparatus of claim 24 wherein said SMS-IP initiates the arming of the PLMN by sending a message to the mobile subscriber, the message formatted in a Short Message Service (SMS) format.

26. In an IN (Intelligent Network), apparatus for indicating at least an activity-status change of an initially-inactive mobile subscriber operable in a PLMN
(Public Land Mobile Network), the PLMN coupled to the IN, said apparatus comprising:
a SCP (Service Control Point) for controlling initiation of monitoring of the mobile subscriber and for receiving indications of the change in status of the initially-inactive mobile subscriber;
an SMS-IP (Short Message Service-Intelligent Peripheral) coupled to said SCP and to the PLMN, said SMS-IP for initiating arming of the PLMN to detect renewed activity of the mobile subscriber, for receiving an alert from the PLMN
alerting said SMS-IP of the change in status, and for providing said SCP with the indications of the change in the status of the mobile subscriber; and wherein said SMS-IP provides said SMS-IP with the indications of the change in status of the mobile subscriber by issuing a MAILBOX STATUS REPORT
to said SCP, the MAILBOX STATUS REPORT issued responsive to receipt, at said SMS-IP, of the alert from the PLMN.