CA2265560C - Roaming process and pertaining devices - Google Patents

Abstract

Telecommunications process enabling a subscriber in a Home Public Land Mobile Network (HPLMN) to connect to a Visitor Public Land Mobile Network (VPLMN) without a roaming agreement with the HPLMN. Connection is achieved by means (IMSI-PPLMN, 3,5) which are made available by a partner unit (PPLMN) having a roaming agreement with both the HPLMN and the VPLMN. In a first embodiment of the invention, connection is established by replacing the international mobile subscriber identification (IMSI) for a HPLMN with an identification for a partner network on the subscriber identification module (SIM) card.

Description

?2025CA 02265560 1999-03-04Roaming Process and Appurtenant DevicesTechnical FieldThe present invention relates to roaming in a radio network,particularly in a mobile radio network.Although the following description deals particularly with the problemof roaming between mobile networks of the GSM type, the invention alsorelates to roaming between any kinds of mobile radio networks, terrestrial or viasatellite, as well as roaming between different kinds of networks.State of the ArtMobile telephone networks of the GMS type have existed since thebeginning of the nineties. At present more than 200 networks of this type existworldwide. In addition, other mobile radio networks exist which operate withother different analog or numeric standards. These different networksgenerally cover various geographical regions, for example various countries.However, there is some overlapping between networks and, for example insome countries, several mobile networks exist alongside one another in thesame region.The mobile radio subscribers have generally concluded asubscription or another type of agreement with a certain mobile network whichis generally operated at their place of residence, for example with a nationalnetwork. This particular network for a certain subscriber is called a homemobile radio network, or more frequently by the English acronym HPLMN(Home Public Land Mobile Network). Still, it is desirable for a subscriber to beable to make and receive calls even when he leaves his HPLMN, that is, whenhe goes to a visited mobile radio network (VPLMN, Visited Public Land MobileNetwork). In the same way, it is necessary that the calls which are made by amobile radio subscriber during a visit to a VPLMN may be billed to thesubscriber by the operator of the HPLMN and that the sums accruing may beredistributed between the HPLMN and the VPLMN. These possibilities?202530CA 02265560 1999-03-04presently require the conclusion of bilateral agreements between the operatorsof the GMS networks. These agreements are known as roaming agreements.Roaming processes are described, for example by l. Brini et al. in"lnternational roaming in digital cellular networks," CSELT Technical Reports,Volume XX, No. 6, Italy, December 1992, pp. 531-536, or by the same authorsin "European roaming related technical problems" CSELT Technical reports,Volume XX, No. 3, Italy, June 1992, pp. 209-215. Bent Gabelgaard gives moreexact information on the concept of the home file (HLR, Home LocationRegister) in a GSM environment in "The (GSM) HRL - Advantages andChallenges," 1994, Records of the Third Annual International Conference onUniversal Personal Communications, San Diego, 27 September-1 October1994, published by IEEE in New York, 1994, pp. 335-339. More exactinformation concerning the establishment of connections in a GSM network areto be found above all in W095/10174.An older mobile network in a populated country may have concludednumerous bilateral roaming agreements, for example more than 50. For anewer mobile network it is difficult or impossible to conclude a comparablenumber of roaming agreements quickly, particularly if this network covers ageographical region which is sparsely settled or in which the potential ofpossible mobile telephone subscribers is slight. Moreover, the costs whicharise through the conclusion of a roaming agreement between two networks,for the testing of the roaming connections, and for the periodic preparation ofexchanged billing files (TAP files) may prove to be troublesome when the trafficbetween these two networks is light. Hence the incentive for new networks islimited since the subscribers do not have the possibility of using their terminalsin a large number of countries. The restriction of the number of roamingagreements thus represents a competitive disadvantage for the operators ofnew mobile networks.?CA 02265560 1999-03-04-3-Patent specification W096/13954 (Ericsson) describes aprocess which enables the subscribers of a home mobile radio network toestablish a telephone connection from a visited mobile radio network withoutroaming agreement to the home mobile radio network. The processcomprises a step of a manual entry in a visitor table. This step of the manualentry is troublesome for the traveling subscriber. This patent relates only tothe signaling problems but in no way to the problem of invoicing and clearing.Patent speci?cation W095/27382 (Ericsson) describes a processwhich enables the subscribers of a radio network of the PDC type (PersonalDigital Cellular) to use their terminals in a network of the GSM type ("lnterStandard Roaming"). The arrangement described comprises, besides the twonetworks, PDC and GSM, a roaming arrangement which carries out thenecessary formal conversion for the signals exchanged between the GSMnetwork and the PDC network. The roaming arrangement is looked upon bythe subscriber file HLR1 of the PDC network as a local exchange center andis looked upon by the local exchange center of the region of the GSM networkin which the traveling subscriber is situated as subscriber file HLR. Theroaming arrangement described contains a roaming file (ILR) with a list of allsubscribers in the PDC network who are entitled also to use the GSMnetwork. When the PDC network is extensive, the size of the roaming filemay become considerable and its administration costly. Hence this solutionstrives for the possibility of a roaming agreement between two radio networkswhich use different standards but does not enable the operator of a newnetwork to extend the number of roaming agreements quickly and more cost-effectively. Here, too, this patent does not allude to the problem of invoicingand clearing.Patent speci?cation GB-A-2280085 describes a telecommunica-tions method with which a subscriber of a AMPS/D—AMPS network (D) can logonto a GSM network. The operator of the AMPS/D-AMPS network (D) needsa cooperation agreement with at least one GSM network A. The subscriberneeds a new GSM-SIM card and a GSM mobile device in order to be able totelephone in network A or in another network with a roaming agreement with?CA 02265560 1999-03-04-33-A. The bills are nevertheless sent to him by the operator of the AMPS/D-AMPS network (D).Hence a task of the invention is the broadening of the roamingpossibilities which can be offered to the subscribers by a network operatorwithout having to conclude a large number of roaming agreements. . .Explanation of the InventionAccording to the invention, the above-mentioned tasks are solved bythe features which are recited in the independent claims, the preferredexemplary embodiments further being mentioned in the dependent claims.In particular, these tasks are solved by offering to a network, forexample a new network or one which has concluded few roaming agreements,?2030CA 02265560 2005-05-06the roaming possibility of another partner network, preferably of a networkwhich has concluded a large number of roaming agreements.ln particular, these tasks are solved by a telecommunication processwhich enables a subscriber of a home mobile radio network (HPLMN, HomePublic Land Mobile Network) to log on to a visited mobile radio network(VPLMN, Visitor Public Land Mobile Network) without roaming agreement withthe home mobile radio network, the connection taking place by means (lMSl-PPLMN 3, 5) made available by a partner unit (PPLMN) which has a roamingagreement with the home mobile radio network, on the one hand, and with thevisited mobile radio network, on the other hand.The description mentions several exemplary embodiments of theinvention, all of which enable the operator of a new mobile radio network whichhas concluded few roaming agreements to offer his subscribers the roamingpossibilities of another network which has concluded a large number ofroaming agreements. The advantage consists in the fact that the subscribersof the new mobile network can immediately profit by all roaming agreements ofthe other mobile network. Consequently, the mobile network which makes itsroaming agreements available is called a partner network or PPLMN (PartnerPublic Land Mobile Network).According to a ?rst exemplary embodiment of the invention, the tasksof the invention are solved substantially by means of a programmable device, forexample a SIM (Subscriber Identity Module) card, provided with a novel programwhich is hereafter called UBlCOM program for SIM card, as well as by means ofa turntable controlled by software which is hereafter called UBlCOM Manageradministration program. The turntable can access both the home ?le (HLR) ofthe home network HPLMN and the home ?le HLR of the partner networkPPLMN.According to this first exemplary embodiment, the SIM card containsin a conventional manner a first set of subscriber identifying data (lMSl—HPLMN, international Mobile Subscriber Identity) in the home mobile radio?202530CA 02265560 2005-05-06network HPLMN. The card further contains a second set of subscriberidentifying data (IMSI-PPLMN) in a partner mobile radio network (PPLMN)administered by an operator which has a roaming agreement with the homemobile radio network. Means for modifying the identifying data (identity) makepossible a replacement of the data set used according to the mobile radionetwork in which the terminal is currently situated. Through this mechanism,the subscriber of HPLMN can be recognized by the operator of the visitedVPLMN network as a subscriber of PPLMN and can thus use the VPLMNnetwork with the same roaming possibilities as are offered to the subscribers ofPPLMN.However, this exemplary embodiment requires updating or anexchange of the SIM cards of all subscribers of the HPLMN network who wishto take advantage of the roaming possibilities offered by the PPLMN partnernetwork.According to a second exemplary embodiment of the invention,presuppose the connection requirements which are sent out by a subscriber ofthe home mobile radio network (HPLMN) from a visited mobile radio network(VPLMN-NR) without a roaming agreement with the home mobile radio network,the sending-out of signals, for example of an authentication inquiry, to anintermediate turntable which is administered by an operator of a partner network(PPLMN) having a roaming agreement with the home network HPLMN, on theone hand, and with the visited network VPLMN-NR, on the other and. In thesesignals, the turntable replaces the subscriber’s location information (Ll-HPLMN)by data corresponding to a subscriber in the partner radio network (LP-PPLMN).The second exemplary embodiment of the invention thus comprisesa step in which these location data (Ll) of the subscriber are modified in such away that a connection can be established. In this second exemplaryembodiment, however, the means for data modification are integrated in aturntable and not implemented in the form of an information module in thesubscriber's SIM card.?2025CA 02265560 2005-05-06Still, these two exemplary embodiments are not completelytransparent to the operators of the radio network since they do not know theidentity and/or the exact location of the subscriber. Some operators propose totheir subscribers bargain subscription possibilities which exclude calls from orinto certain regions of the world. Such restrictions could be circumvented incertain cases through the use of one or the other of these exemplaryembodiments.According to a third exemplary embodiment of the invention,establishment of the connections from the visited mobile radio network (VPLMN)takes place via at least one intermediate turntable with which both the homemobile radio network and the visited mobile radio network have signed aroaming agreement. Yet the connections established from the visited mobileradio network (VPLMN) do not necessarily go via the turntable.In this case, the turntable has the task of a central roaming turntablebetween all radio networks. The turntable is preferablly administered by apartner unit, for example by the operator of a radio network (PPLMN) which hasalready concluded roaming agreements with a large number of networks. Ifneed be, these agreements must be replaced or supplemented by subsidiaryagreements which make it possible to carry out the process of the invention.Brief Description of the DrawingsThe invention is explained in more detail by the description which isgiven as an example and illustrated by the figures, of which:Figure 1 shows diagrammatically a radio system which shows ahome mobile radio network (HPLMN), a visited mobile radio network (VPLMN),and a partner radio network (PPLMN), as well as means according to the firstexemplary embodiment of the invention which enable a subscriber of HPLMN touse his terminal in the VPLMN;?2025CA 02265560 1999-03-04Figure 2 is a flow chart showing the program which is carried out bythe SIM card according to the first exemplary embodiment of the invention;Figure 3 is a flow chart showing another embodiment of the programwhich is carried out by the SIM card according to the first exemplaryembodiment of the invention when the SIM Toolkit GSM11.14 is available;Figure 4 shows diagrammatically a radio system comprising a homemobile radio network (HPLMN), a visited mobile radio network (VPLMN), and apartner radio network (PPLMN), as well as means according to the secondexemplary embodiment of the invention which enable a subscriber of HPLMN touse his terminal in the VPLMN;Figure 5 shows diagrammatically a radio system comprising a homemobile radio network (HPLMN), a visited mobile radio network (VPLMN), and aturntable administered by a partner unit, as well as means according to thethird exemplary embodiment of the invention which enable a subscriber ofHPLMN to use his terminal in the VPLMN;Figure 6 is a flow chart showing certain steps of the clearing andinvoicing process which are carried out by the clearing and invoicing unit of theturntable according to the third exemplary embodiment of the invention;Figure 7 shows diagrammatically the course of invoicing andpayment in a radio system according to the third exemplary embodiment of theinvention comprising a home mobile radio network (HPLMN), a visited mobileradio network (VPLMN), and a turntable administered by a partner unit.An embodiment of the first variant of the invention will now bediscussed with reference to Figures 1 to 3. The radio system of the inventiondepicted as an example comprises a home mobile radio network (HPLMN,Home Public Land Mobile Network), for example a radio network according tothe GSM standard, a partner radio network (PPLMN, Partner Public LandMobile Network), as well as a visited radio network (VPLMN, Visited PublicLand Mobile Network). The three networks HPLMN, PPLMN, and VPLMN each?202530CA 02265560 1999-03-04comprise at least one home file HLR (Home Location Register), which is calledHLR-HPLMN, HLR-PPLMN, or HLR—VPLMN. The other elements which formthe mobile networks, such as terminals (mobile telephones), cells, basestations, base station control units, exchanges, etc., are known according to thestate of the art and are thus not depicted. The visited network VPLMN has noroaming agreement with the home network HPLMN, which is indicated by theacronym VPLMN—NR (VPLMN with No Roaming Agreement).It goes without saying that the radio system depicted here isintended only as a non-restricting example and that the invention is applicablealso to more complex radio systems comprising a large number of mobile radionetworks which operate according to one or more standards and only some ofwhich are connected by bilateral roaming agreements.The letter S designates a subscriber of the home mobile radionetwork HPLMN. When he is in the geographical region served by his homenetwork HPLMN, the subscriber 1 can telephone by means of his terminal, forexample a portable telephone, and use the services offered by his HPLMN in aquite normal manner. The terminal 1 contains a programmable device 10, forexample a chip card which in the GSM networks is called a SIM card(Subscriber Identification Module). SIM cards are described for example byTheodora Grogorova et al. in "SIM Cards," Telecommunication Journal ofAustralia, Vol. 43, No. 2, 1993, and make possible above all the storage of asubscriber identification code designated by the acronym IMSI (InternationalMobile Subscriber Identity). The SIM card further contains a processor 102which can carry out various algorithms.When the subscriber leaves his home network HPLMN and comesinto a visited network which has a roaming agreement (not shown) with hisHPLMN, subscriber S can use his terminal quite normally with the aid of theconventional roaming processes which are described for example in the above-mentioned documents. However, when the subscriber S goes into a visitednetwork VPLMN—NR which has not concluded any roaming agreement with hishome network, the subscriber can no longer use the IMSI identification code ofhis card to log on since the visited network does not accept this identification?202530CA 02265560 1999-03-04code. According to the state of the art, the subscriber can thus neither carryout nor receive calls from the geographical zone covered by a VPLMN—NR.According to the first exemplary embodiment of the invention, theSIM card 10 contains a computer program designated as UBICOM program.The UBICOM program makes possible the exchange of the identification codeof the subscriber from the HPLMN network (IMSI-HPLMN) for a correspondingidentification code of a subscriber in the partner network PPLMN (lMSl-PPLMN). The subscriber S is thus considered in the visited network VPLMN-NR to be a traveling subscriber who comes from the partner network PPLMN.Since the PPLMN network has a roaming agreement with the visited networkVPLMN—NR, the subscriber S can thus log on and carry out or receive calls inthe VPLMN—NR.The partner network PPLMN contains in a conventional manner alocation file HLR-PPLMN in which, according to a procedure conventional for aGSM network, the information is registered that the subscriber S (who isidentified by the |MS|~PPLMN) is now in the VPLMN—NR. According to theinvention, the PPLMN network further comprises a turntable with thedesignation UBICOM (2) which is controlled by software hereafter calledadministration program UBICOM. The turntable 2 is informed by an alarmwhen the subscriber S is registered in the HLR-PPLMN files. The output ofsuch alarm signals is known according to the state of the art and is for examplealready used when a short message SMS is temporarily stored and when atraveling subscriber again logs on in his network. In such a case, theadministration center for short messages SMSC is informed by an alarm thatthe short message can now be sent out. This function may also be used inorder to inform the file administration program UBICOM 2; however, it is alsopossible to use another function.The turntable UBICOM 2 recognizes the correspondence betweenthe lMSl—PPLMN and the |MS|—HPLMN of each subscriber. In the same way,the turntable UBICOM 2 recognizes the correspondence between theidentification number MSISDN of the terminal 1 in the PPLMN (PPLMN-MSISDN, Mobile Station ISDN Number) and in the HPLMN (HPLMN—MSlSDN).?202530CA 02265560 1999-03-0410When the turntable 2 discovers that the subscriber S is using the identificationcode PPLMN—lMS| of the PPLMN, it sends a message to the location file HPLR-HPLMN of S's home network (HPLMN), which activates or deactivates a calldiversion (CFU, Call Forwarding |nconditional[sic]). This message causes thediversion of all calls intended for the MSISDN-HPLMN to the MSISDN-PPLMN.Thus the identification code of the terminal MSISDN—HPLMN may be used forcalling the subscriber S. The process is automatic and transparent to thesubscriber.When the subscriber 3 leaves the visited network VPLMN-NR andreturns to his home network HPLMN, he first logs on with the aid of theidentification code PPLMN-IMSI. This reconnection to the HPLMN network isregistered in the location file of PPLMN through the mechanism describedpreviously. The turntable UBICOM 2 now issues an alarm to the home networkHPLMN for suppressing the diversion CFU.The SIM card 10 of the subscriber S is informed in the same wayupon reconnecting to the HPLMN that the subscriber S has returned to hishome network. The UBICOM program of the SIM card again exchanges theidentification code of the subscriber IMSI in the partner network PPLMN (IMSI-PPLMN) for a subscriber identification code in the home network HPLMN(IMSI-HPLMN). Thus, after the reconnection to his home network, thesubscriber S can switch his terminal 1 off and on again in order to telephoneagain with his own IMSI and his MSISDN which are defined in his homenetwork. The mechanism of the invention is reactivated only if the subscriber Sagain goes into a network without a roaming agreement VPLMN-NR.The steps of the UBICOM program carried out by the SIM card of theinvention will now be described with reference to Figure 2.The UBICOM program of the SIM card is automatically run uponeach resetting of the card, for example after switching the terminal 1 on. TheSIM card of the invention contains, besides the usual files of the standardGSM, an additional file EFUBICOM containing the following information:?2025CA 02265560 1999-03-0411— A processing flag 100 indicating whether the UBICOMmechanism is activated or not.— The subscriber identification code in the home network lMSl—HPLMN.- The subscriber identification code in the partner network |MSl—PPLMN.— The home country code (MCC, Mobile Country Code) and thehome network code (MNC, Mobile Network Code).- A list 101 of the MCC codes of all countries and of the MNCcodes of all VPLMN networks which have concluded a roaming agreement withthe home network (VPLMN—WR, VPLMN With Roaming Agreement).This list can be dynamically completed or updated, for example bymeans of a procedure known by the designation SICAP and described in patentapplication EP94810363.5 in the name of the applicant, or by means of anyother suitable procedure such as ESMS, etc.It is known to one skilled in the art that these different items ofinformation are cited as an illustrative example and that they can just as well bedivided up into several files.The UBICOM program run by the processor of the SIM card beginswith step 30 ATR (Answer to Reset). In step 31 the processing flag showingwhether the UBICOM mechanism is activated is tested. The UBICOM programis immediately interrupted when the processing flag indicates that the UBICOMmechanism is not activated, and in this case the processor of the SIM cardimmediately continues carrying out the normal operations from step 37 on,which are carried out after a conventional reset.If the UBICOM mechanism is activated, the program reads in step 32the conventional file EFLOCI (Elementary File for Location Information). In?30CA 02265560 1999-03-0412step 33 the program checks whether the file EFLOCI contains the code of themobile network (MNC, Mobile Network Code) of the home network HPLMN orthe code of a network VPLMN—WR which is specified in the file EFUBICOM,that is, of a network which has concluded a roaming agreement with theHPLMN network.In case of an affirmative result of the check 33, that is, if the fileEFLOCI indicates that the subscriber S is currently in a network whichrecognizes the identification code IMSI of his home network HPLMN, theUBICOM program continues with the check 34 in which the subscriberidentification code IMSI is checked (file EFIMSI). If the subscriber identificationcode IMSI corresponds to an identification code in the partner network PPLMN,the program continues with the following step 35 in which the subscriberidentification code IMSI-PPLMN is replaced by the identification code IMSI-HPLMN in the home network of the subscriber. The program thereafter carriesout the operation 36 in which the file EFLOCI is deleted, for example byinputting the hexadecimal value "FF FF FF The UBICOM program is thereafter terminated, and the processor ofthe SIM card thereafter continues with step 37 in which the normal functions ofthe SIM card are carried out. If the subscriber S actually is in his HPLMN or ina VPLMN-WR, he can thus log on to the network normally using his IMSI-HPLMN. The file EFLOCI is now updated with the identification code of themobile network to which the subscriber logs on.If, however, the subscriber S is in a network VPLMN-NR without aroaming agreement, he cannot log on with his lMS|—HPLMN since no roamingagreement exists between the HPLMN and VPLMN-NR networks. Hence thesubscriber S can neither telephone nor receive a call, so that the file EFLOCI isnot updated and remains deleted. The subscriber then switches his terminal offand on again, which causes the UBICOM program to be re—run. One skilled inthe art can imagine without difficulty another, more elegant way of restartingrunning of the UBICOM program.?2025CA 02265560 1999-03-0413In this re-running of the UBICOM program, the file EFLOCI is thusdeleted. The result of the check 33 is thus negative, whereby it is indicated tothe SIM card that the subscriber identification code in the home network IMSI-HPLMN cannot be used since the subscriber S is currently in a network withouta roaming agreement with his home network HPLMN. In this case the UBICOMprogram continues with the check 38 in which the subscriber identification codeIMSI is checked (file EFIMSI). If the subscriber identification code IMSIcorresponds to an identification code in the home network HPLMN, theprogram continues with the following step 39 in which the subscriberidentification code IMSI-HPLMN is replaced by the identification code lMSl-PPLMN in the partner network PPLMN, so that the subscriber S can log on.Hence there are four possible situations upon switching on theterminal:1) The subscriber is in his home network HPLMN or in a visitednetwork having a roaming agreement VPLMN—WRThe file EFLOCI is read first of all. The UBICOM programdetermines in step 33 that the contained information corresponds to theidentification code of HPLMN or of a VPLMN—WR. The subscriber identificationcode |MSI—HPLMN can continue to be used and the file EFLOCI be deleted forexample with the data "FF FF FF."The UBICOM program is now terminated, and the processor of theSIM card can carry out the normal functions of the SIM card.2) The subscriber 8 comes from a visited network withoutroaming agreement VPLMN—NR into his home network HPLMN or into a visitednetwork having a roaming agreement VPLMN-WR.The file EFLOCI is read first of all. The UBICOM programdetermines in step 33 that the contained information corresponds to theidentification code of HPLMN or of a VPLMN—WR. The subscriber identificationcode lMSl—PPLMN is subsequently replaced by the identification code in the?2025CA 02265560 1999-03-0414home network lMSl-HPLMN and the file EFLOCI then deleted, for example withthe data "FF FF FF."The UBICOM program is now terminated, and the processor of theSIM card can carry out the normal functions of the SIM card.3) The subscriber S comes into a visited network withoutroaming agreement VF'LMN—NR from his home network HPLMN or from avisited network with a roaming agreement VPLMN—WRThe SIM card cannot establish any connection to the VPLMN-NRnetwork since the IMSI-HPLMN is not authorized in this network. The fileEFLOCI is still deleted, for example with the data "FF FF FF."The mobile telephone is then switched off and switched on again,and the UBICOM program is run a further time. EFLOCI is still empty upon thissecond running. The processor now replaces, in step 39, the subscriberidentification code lMSl-HPLMN by the identification code in the partnernetwork lMSl-PPLMN.The UBICOM program is now terminated, and the processor of theSIM card can carry out the normal functions of the SIM card.4) The subscriber S is in a visited network without roamingagreementThe file EFLOCI is read first of all. The UBICOM programdetermines in step 33 that the contained information corresponds to theidentification code of a VPLMN-NR. The subscriber identification code lMSl-PPLMN can continue to be used.The UBICOM program is now terminated, and the processor of theSIM card can carry out the normal functions of the SIM card.?15202530CA 02265560 1999-03-0415Figure 3 shows a variant of the program carried out by the processorof the SIM card according to a first exemplary embodiment of the invention.With reference to the variant depicted in Figure 2, this variant makes it possiblefor the terminal 1 not to have to be switched off and then switched on again inorder to re-run the UBICOM program. For this purpose, in this variant theprogram comprises two additional steps 40 and 41 in which the SIM card sendsdirectly to the terminal (ME, Mobile Equipment) an inquiry which makes itpossible to obtain the subscriber identification code IMSI directly.This additional possibility is made available above all by theadditional functions of the SIM cards according to the GSM11.14 toolkit.It is known to one skilled in the art that the SIM card according to theinvention is preferably provided with a conventional encoding key K1. This keyis used for encoding both the IMSI-HPLMN and the lMSl—PPLMN. Aprerequisite for faultless operation of the process of the invention is thus acorrespondence between the identification code algorithm used by the PPLMNnetwork and by HPLMN.In the variant described before, for carrying it out the UBICOMprogram must be loaded in all SIM cards of subscribers in the mobile networkHPLMN. This loading can be carried out for example with the SICAP processdescribed in the already mentioned patent application EP94810363.5. If theoperator of the HPLMN network has not yet used the SICAP process, or if thestorage or processing capacity of the distributed SIM cards is not sufficient forreliable running of the UBICOM program, it may be necessary to exchange theSIM cards of the subscribers who want to use the novel roaming possibilitiesoffered indirectly via a partner network PPLMN. in view of the slight cost ofthese cards and of the prospective increase in traffic, such an exchange isquite conceivable.There will now be described with reference to Figure 4 a secondexemplary embodiment of the invention which can be carried out withoutupdating and without exchanging the SIM cards of subscribers.?202530CA 02265560 1999-03-0416This exemplary embodiment uses an international turntable 3situated for example in the country or region which is served by the partnernetwork PPLMN, or in another suitable region. Ideally, the turntable 3 shouldbe disposed in an intermediate position between the HPLMN network and theVPLMN-NR network. Corresponding to the number of subscribing networks, itmay be advantageous to use several turntables, for example one per continent.The turntable 3 is preferably administered by the operator of apartner network PPLMN or by another appurtenant unit of the operator or a unitin touch with the operator. The PLMN networks which want to expand theirroaming offer by adding the turntable 3 must conclude a special roamingagreement with the operator of this turntable. As will be shown, only a fewminor adaptations are necessary on the part of the PLMN networks in order touse the turntable 3. These special agreements can thus be concluded withoutdifficulty with the mobile networks VPLMN which have already concluded aroaming agreement with the PPLMN network. On the other hand, bilateralagreements between all PPLMN networks which want to use the turntable 3 arenot necessary.Carrying out this second exemplary embodiment of the inventionrequires that the subscribing VPLMN networks accept the requests to log on ofthe other VPLMN networks even when they have no roaming agreementamongst themselves.The turntable 3 preferably consists of a programmable device whichcan be connected simultaneously to the HPLMN network and every mobilenetwork PLMN which has joined this mentioned, special agreement. Theturntable 3 is preferably controlled by a computer program recorded on arecording carrier 30, as for example a diskette, hard disk, or an optical diskstorage which can be read by the turntable 3.For simpler representation, a single VPLMN network is drawn inFigure 4 in addition to the home network HPLMN of the subscriber 8; it goeswithout saying, however, that a radio system according to this secondexemplary embodiment offers an advantage above all when the number of...-....................n..... ., . . _.".?202530CA 02265560 1999-03-0417networks which have joined is large. Moreover, just as in Figure 1, only thestructures of the HPLMN and VPLMN networks essential to the explanation ofthe invention are depicted.It is assumed that a subscriber S who is a subscriber of the homenetwork HPLMN goes into the network VPLMN—NR without a roamingagreement with the HPLMN network. Still, the home network HPLMN and thevisited network VPLMN—NR have both concluded a special roaming agreementwith the partner network PPLMN. When the subscriber S tries to log on withhis terminal to the VPLMN-NR network, the latter determines based upon thesubscriber identification code HPLMN—|MS| that the subscriber S comes fromthe HPLMN network with which no bilateral roaming agreement has beenconcluded. In principle, the VPLMN-NR network would have to refuse therequest to log on.Because of the special roaming agreement with the partner networkPPLMN, however, the subscribers of the HPLMN network are regarded in theVPLMN—NR as subscribers of the PPLMN network. The special roamingagreements thus require of the networks which have joined that they modify thehome file HLR andlor the exchange centers MSC in order to identify the SIMcards of the subscribers of the other networks which have joined, especially ofthe home network HPLMN of the subscriber S, and that they treat thesesubscribers as subscribers of the partner network PPLMN. Consequently, inaccordance with the GSM protocols, the VPLMN—NR network sends anauthentication inquiry 7 to the PPLMN network. This inquiry is dealt with in thePPLMN network by the turntable 3 which has been set up especially for thispurpose within the scope of this invention.The authentication inquiry transmitted by the VPLMN—NR networkcontains in particular the information concerning the location of the subscriberS (Ll, Location Information), so that the turntable 3 now knows that thesubscriber S is in the VPLMN-NR network. The turntable 3 modifies thislocation information by replacing it with L|—PPLMN data indicating that thesubscriber is in the PPLMN network and then transmits the thus modifiedauthorization inquiry to the home network HPLMN of S (arrow 8). Thus the?202530CA 02265560 1999-03-0418turntable 2 [sic] "lies to" the HPLMN network by pretending that S is in thepartner network PPLMN.As already described, the home network HPLMN has concluded aroaming agreement with the PPLMN network. The home file HLR of the homenetwork HPLMN first checks whether the subscriber S is authorized to use histerminal in the partner network PPLMN, and if the result of this check isaffirmative, a corresponding reply 9 is sent to the turntable 3, which transmits iton to the visited network VPLMN-NR (arrow 11). This reply is compared in thisnetwork with a reply which has been received from the SIM card 10 of theterminal 1 of the subscriber S, and if the result of this check is affirmative, thesubscriber S is considered authorized and is entered in the visitor file VLR—VPLMN (Visitor Location Register of VPLMN). The complete |og—on processmay comprise several interrogations and replies additionally exchangedbetween the visited network VPLMN-NR and the home network HPLMN whichrun through the turntable 3 each time. For example, the visited network mayask the home network about special services for the use of which thesubscriber S has an authorization.At the end of this process of the subscriber S logging on to thevisited network VPLMN-NR, the latter treats S as though he were a subscriberof PPLMN and transmits the connection requests carried out by S, which itcannot establish directly, to the turntable 3, which is administered by PPLMN.Conversely, the HPLMN network transmits the calls intended for S to theturntable 3.The connection requests and the calls from or for S, which arerepresented by the arrow 12, thus run via the PPLMN network and via theturntable 12 [sic]. For the particular case where the mobile networks HPLMNand VPLMN-NR have different standards, for example if a subscriber of a GSMnetwork comes into a PDC network, the turntable 3 may comprise conversionmeans known according to the state of the art which make possible aconversion of the formats of the connection requests and calls.?202530CA 02265560 1999-03-0419In the VPLMN—NR network, the subscriber S is regarded as asubscriber of the partner network PPLMN. Further, the home network HPLMNdoes not know the exact location of S when he is in the VPLMN—NR networkand assumes that he is in the partner network PPLMN. Hence this variant isnot completely transparent to the home radio network HPLMN of the travelingsubscriber S since it does not know the exact location of the subscriber. Someoperators offer their subscribers bargain subscription possibilities whichexclude calls from or into certain regions of the world. These restrictions mayin certain cases be circumvented through the execution of this secondexemplary embodiment.A third exemplary embodiment of the invention which does not havethese disadvantages will now be described with reference to Figure 5.The third exemplary embodiment of the invention requires that allparticipating PLMN networks conclude a special roaming agreement with theoperator of a turntable 5, for example with a partner network PPLMN or with acompany which administers such a turntable. As will become obvioushereafter, through the conclusion of such a special agreement, each networkwhich has joined can offer its subscribers roaming possibilities in every othernetwork which has joined; hence no bilateral roaming agreements between allnetworks which have joined are necessary. When the number of networkswhich have joined is large, a new network having only few roaming agreementscan thus offer its subscribers the same possibilities with a single roamingagreement concluded with the turntable 5 as those offered by alreadyestablished networks which have joined. Upon the joining of new mobilenetworks, it is necessary only to reconfigure the turntable 5 and to check theconnections between the new mobile network and the turntable; no adaptationis required on the part of the networks which have already joined.The mobile networks need a special roaming agreement in order tobe able to use the turntable. This agreement regulates the points ordinarilycited in a roaming agreement, which are recommended for example in the GSMMemory of Understanding, as well as the following points specific to the systemof the invention:?2025,. .. ..«......................................A.,CA 02265560 1999-03-0420- Naming of the other networks which have joined with which thenew network would like to use the roaming possibilities via the turntable 5.— Routing of the necessary signaling signals for connecting viathe turntable 5.— Initial tests for checking the quality of the connections betweenthe new network which has joined and the turntable 5. A test of the bilateralconnections with every other network which has joined is not necessary.— Periodical supplying of the invoicing files (TAP files) to theturntable 5.- Amount of the call charges billed by the new network whichhas joined.- etc.The turntable 5 may, like the turntable 3 in the second exemplaryembodiment, be disposed in the country or region served by the partnernetwork PPLMN or in some other suitable region. Several turntables,geographically distributed, may prove to be suitable. The turntable ispreferably administered by the operator of the partner network PPLMN or byanother appurtenant unit of the operator or a unit in touch with the operator.The international turntable 5 preferably consists of a programmabledevice which can be simultaneously connected to the HPLMN network and toevery PLMN network which has joined this particular said agreement. It ispreferably controlled by a computer program recorded on a recording carrier50, as for example a diskette, hard disk, or an optical disk storage which can beread by the turntable 5.It is assumed that a subscriber S who is a subscriber of the homenetwork HPLMN goes into the network VPLMN-NR without a roamingagreement with the HPLMN network. Still, the home network HPLMN and the?202530CA 02265560 1999-03-0421visited network VPLMN—NR have both concluded a special roaming agreementwith the partner network PPLMN. When the subscriber S tries to log on withhis terminal to the VPLMN—NR network, the latter determines based upon thesubscriber identification code HPLMN—|MSl that the subscriber S comes from anetwork (HPLMN) with which no bilateral roaming agreement has beenconcluded. In principle, the VPLMN—NR network would have to refuse therequest to log on.However, the VPLMN—NR has storage means 13 containing a list ofthe network identification codes (NC) of the networks joined to the intermediateturntable 5. Thus, the VPLMN—NR determines that the subscriber S comesfrom a network joined to the intermediate turntable 5. In this case, based onthe mentioned special roaming agreements, the VPLMN—NR network sends anauthentication inquiry 14 to this turntable 5. The turntable 5 transmits thisinquiry immediately to the home file HLR of the home network HPLMN (arrow15) without changing the possibly contained location information Ll-VPLMN.The home file HLR—HPLMN first checks whether the subscriber S isauthorized to use his terminal in the networks which have joined, and if theresult of this check is affirmative, a corresponding reply 16 is sent to theintermediate turntable 5, which transmits it to the visited network VPLMN—NR(arrow 17). This reply is compared in this network with a reply obtained fromthe SIM card 10 of the terminal 1 of the subscriber S, and if the result of thischeck is affirmative, the subscriber is regarded as authorized and entered inthe visitor file VLR-VPLMN (Visitor Location Register of VPLMN). As in thesecond exemplary embodiment described previously and as in the conventionalroaming protocols, the complete log—on process may comprise severalinterrogations and replies additionally exchanged between the visited networkVPLMN—NR and the home network HPLMN, which run through the intermediateturntable 5 each time. For example, the subscriber identification code lMSl-HPLMN may, of course, also be transmitted between the visited network andthe home network via the turntable 5. Moreover, the visited network may askthe home network about special services for the use of which the subscriber Shas an authorization.?2030CA 02265560 1999-03-0422According to this third exemplary embodiment, the home file of thehome network HLP—HPLMN stores the correct location of the subscriber S inthe visited network VPLMN—NR; this information is not changed by theintermediate turntable 5. Conversely the visitor file VLR of the visited networkVPLMN correctly stores the identification code of the home network HPLMN ofthe subscriber S and thus does not consider S a subscriber of the partnernetwork PPLMN. The connection requests 18 which are intended for thesubscriber S and come for example from his home network HPLMN canconsequently be routed directly between the home network HPLMN and thevisited network VPLMN-NR without running via the turntable 5. Conversely, thecalls made by S intended for a subscriber outside the visited network VPLMN-NR are routed directly via the location file HRL-HPLMN of S's home networkwithout running via the turntable 5.Depending on the type of network, various signals can beexchanged between the visited network and the home network upon thesubscriber S's |ogging—on in the visited network. According to the thirdexemplary embodiment of the invention, at least some of these signals aretransmitted between the visited network and the home network via theintermediate turntable 5 which is administered by a network partner PPLMN.The connection requests from or for S thus run via the turntable 5.In the particular case where the mobile networks HPLMN and VPLMN-NR havedifferent standards, for example if a subscriber comes from a GSM network intoa PDC network, the turntable 5 may comprise conversion means knownaccording to the state of the art which make possible a conversion of theformats of the connection requests.The turntable 5 comprises a clearing and invoicing unit 6.According to the special roaming agreement previously described,each mobile network PLMN which has joined must undertake to supply theturntable 5 with files containing data relating to all calls with roaming use whichhave come from subscribers or were intended for subscribers who were visitingthis network. Similar files are already used in the conventional roaming?202530CA 02265560 1999-03-0423procedures and are called "TAP files." According to the invention, however,these files need not be distributed to every other PLMN network which hasjoined; the operators can group the files containing the data concerning thecalls which comprise the subscribers of every other network which has joined inorder to send them to the turntable 5. It is possible to send either one TAP filefor each HPLMN network which has joined or a single combined file containingall data relating to the calls with all other networks. If no subscriber of aHPLMN network has used his terminal in a VPLMN network since the lastsending of the TAP file, the operator of the VPLMN network preferably soinforms the clearing and invoicing unit by means of a certain notification.The TAP files and the notifications may be sent to the turntable 5 inelectronic form, for example using the well-known exchange format EDI(Electronic Data Interchange). Other carriers, for example magnetic tapes, maynaturally be used within the scope of this invention. The TAP files aretransmitted to the turntable at a rate fixed in advance, preferably daily.The clearing unit 6 in the turntable 5 receives and deals with thereceived TAB [sic] files of various mobile networks (VPLMN) which have joinedand distributes the received information to each home network HPLMN. Theclearing unit is preferably controlled by a computer program registered on arecording carrier 50 as, for example, a diskette, hard disk, or an optical diskstorage. The clearing unit may be provided from the same server as theturntable 5 or executed on another machine administered by the same operatoras the turntable 5. Under the control of this program, the clearing unitpreferably carries out a process, the main steps of which are depicted in theflow chart of Figure 6._ In step 60 the clearing and invoicing unit 6 receives the TAP filesand/or the notifications of each network which has joined, which have beentransmitted for example all day long according to the file exchange protocolEDI. In step 62 the clearing unit 6 now checks for each PLMN network whichhas joined whether all TAP files and all notifications have been received in thefixed period of time, for example within 24 hours after the last sending of TAPfiles. In case of a negative result of this check, a manual or automatic?2025CA 02265560 1999-03-0424inspection is carried out in step 64 at the PLMN networks which have not yetsupplied the necessary files, and the program returns to step 60.In step 66 the TAP files are checked, and in case of an error, theprogram goes to step 64 in order to clarify the problem with the networkconcerned. If the Tap[sic] files do not contain any errors, the clearing unitcopies the received files in step 68 in a suitable format and then in step 70distributes to each home network HPLMN the information relating to the callsfrom or for the subscriber from the visited network into another network whichhas joined.At regular fixed intervals, for example monthly, the clearing andinvoicing unit 6 in the turntable 5 bills (71) each HPLMN network which hasjoined for an amount corresponding to the calls of the subscribers of HPLMN inthe other, visited VPLMN networks which have joined. This amount iscalculated from the information contained in the copies of the TAP files whichhave been supplied by each visited VPLMN network (arrow 75). The arrow 76marks the distribution of the information from the Tap[sic] files to the HPLMN.The bill is sent to the respective HPLMN network by any means, for example inelectronic form (arrow 71). A copy of the bill is preferably sent for informationto each respective VPLMN network (arrow 74).After receipt of this bill, each HPLMN pays the operator of theturntable 5 (arrow 72). It is to be seen that the payment operations carried outby each HPLMN are clearly simplified since the amounts intended for eachVPLMN can be regrouped into a single payment to a single recipient, theoperator of the turntable 5. After receipt of the money remitted by the HPLMN,the clearing and invoicing unit distributes this money to each VPLMN (arrow73), an amount concerning its costs being added to the same bill or shownseparately, In the--frequent-—event that the networks HPLMN and VPLMN donot use the same currency, the clearing unit 6 carries out the necessaryconversions, preferably using an intermediate conversion with the SDR format.

Claims (11)

Claims

1. Telecommunication process which enables a subscriber of a home mobile radio network to log on to a visited mobile radio network (VPLMN, Visitor Public Land Mobile Network) without a roaming agreement with the home mobile radio network, characterized in that a computer programs replaces the identification data of the subscriber with identification data made available by a partner radio network having a roaming agreement with the home mobile radio network, on the one hand, and with the visited mobile radio network, on the other hand.

2. Process according to claim 1, characterized in that the bills run over a unit (6) administered by the partner radio network:.

3. Process according to claim 1 or 2, characterized in that at least one of the mobile radio networks is a GSM network.

4. Process according to any one of claims 1 to 3, characterized in that the radio networks may be of different types.

5. Process according to claim 4, characterized in that the identification data of the subscriber are stored in a storage means (10), for example in a SIM card, which is integrated in the mobile apparatus (1) of the subscriber, and that using an identification modifying means (102) the identification data of the subscriber, dependent upon the mobile radio network in which the mobile apparatus is presently situated, are replaced in the terminal by identification data corresponding to a subscriber in a partner radio network having a roaming agreement with the home mobile radio network, on the one hand, and with the visited mobile radio network, on the other hand.

6. Process according to claim 5, characterized in that the identification data of the subscriber are replaced in the storage means using a processor (102) which runs a computer program stored in the storage means.

7. Process according to claim 6, characterized by a step of checking a processing flag (101) contained in the storage means, upon each reset or upon each switching-on of the mobile apparatus (1), and in that the said computer program is run at the end of the check when the processing flag is set.

8. Chip card (10) which is intended for use in a mobile radio apparatus (1) and makes possible the storage of subscriber identification data, characterized in that it comprises a processor (102) which makes possible a replacement of the subscriber identification data, dependent on the visited mobile radio network in which the mobile radio apparatus is presently situated, by identification data corresponding to a subscriber in a partner radio network having a roaming agreement with the home mobile radio. network in which the subscriber has subscribed, on the one hand, and with the visited mobile radio network, on the other hand.

9. Chip card according to claim 8, characterized in that the means for changing the subscriber identification data contain a computer program which is stored in the programmable device (10) and can be run by a processor (102) on the programmable device.

10. Chip card according to claim 9, characterized in that it further stores a processing flag (100) which is checked upon each reset or upon each switching-on of the mobile radio apparatus (1).

11. Chip card (10) intended for use in a mobile radio apparatus (1) and containing a first set of subscriber identification data from the home radio network, characterized in that it further contains a second set of subscriber identification data from a partner radio network administered by an operator having a roaming agreement with the home mobile radio network.