WO2000049820A1

WO2000049820A1 - Identification module and method in first and second telecommunication networks

Info

Publication number: WO2000049820A1
Application number: PCT/FR2000/000423
Authority: WO
Inventors: René BONGERS
Original assignee: Schlumberger Systemes
Priority date: 1999-02-18
Filing date: 2000-02-18
Publication date: 2000-08-24
Also published as: EP1153517A1; JP2002537738A; CN1341332A; FR2790161A1

Abstract

The invention concerns a method for identifying a subscriber whereby the subscriber is provided with a mobile station (MS) equipped with a subscriber identification module comprising means for identifying himself to a first telecommunication network (11) under a first identity (IMSI1) and means for identifying himself to a second telecommunication network (12) under a second identity (IMSI2). The invention also concerns a subscriber identification module (SIM) for implementing said method. The invention is characterised in that said method comprises the following steps which consist in: defining a first telecommunication network (11) as having priority relative to the second telecommunication network (12); when the subscriber identification module (SIM) is identified in the second telecommunication network (12), verifying at regular intervals whether the mobile station (MS) is within the coverage zone of the first telecommunication network (11); the subscriber identification module (SIM) automatically identifies itself to the first telecommunication network (11) under its first identity (IMSI1), without intervention from the subscriber when he enters the first telecommunication network (11). The invention is particularly applicable to subscriber identification in GSM networks, using SIM.

Description

MODULE AND METHOD FOR IDENTIFICATION WITHIN A FIRST AND SECOND TELECOMMUNICATION NETWORK

The present invention relates to a method for identifying a subscriber within a first and a second telecommunications network, according to which the subscriber has a mobile station provided with a subscriber identification module, said subscriber subscriber identification module comprising means for identifying with the first telecommunications network under a first identity as well as means for identifying with the second telecommunications network under a second identity.

The invention finds a particularly advantageous application in the field of mobile telephony.

In this area, it is common for the subscriber to be able to use his mobile station on another telecommunications network than that for which he has paid a subscription. The only constraint is that the mobile station supports the frequencies of the telecommunications network that the subscriber wishes to use: most countries are in 900 MHz (the initial GSM), some also have networks at 1800 MHz (DCS 1800) , some are only at 1900 MHz (United States) or even use frequencies specific to networks based on satellites. A country is covered by operators who each operate a telecommunications network. Each network covers all or part of the country and thus includes an operating territory. One concept, known as the roaming concept and called in the English language "roaming", allows an operator with low network coverage in a country to offer its subscribers wider network coverage in that country or to allow a subscriber to call when his mobile station is operating outside his country of origin. Agreements concerning the said concept are made between two operators for a fee. The first operator operates the first telecommunications network, while the second called partner has roaming agreements with a third operator which operates the second telecommunications network. In this case, the subscriber identification module of the mobile station comprises two identities making it possible respectively to identify with the first network and with the second network and thus corresponding to two respective subscriber accounts.

A state of the art known and disclosed in the patent document published under the number EP 0 579 655 teaches that, when a subscriber on the first network can no longer telephone because of a loss of coverage of his network, he selects manually his partner account using for example a menu from his mobile station. Said method is not optimum insofar as, on the one hand, the subscriber cannot be called or cannot call the time for selecting the second account, on the other hand, the selection of the second account often seems complicated during said audit. subscriber, and, finally, said subscriber does not know when he can again select the first network on which he is subscribed, that is to say when does his network again cover the territory in which finds its mobile station. Also a technical problem to be solved by the object of the present invention is to propose a method of identifying a subscriber within a first and a second telecommunications network, according to which the subscriber has a mobile station provided with a subscriber identification module, said subscriber identification module comprising means for identifying with the first telecommunications network under a first identity as well as means for identifying with the second telecommunications network under a second identity, as well as a subscriber identification module for implementing such a method, which make it possible, on the one hand, to avoid a subscriber from managing these changes to subscriber accounts himself, and , secondly, to allow a transition from one telecommunications network to another network in a transparent manner to a subscriber, when the coverage of a network is regained, and, finally, to allow a transition from a second network to the first network on which the subscribed user is subscribed, as soon as his station enters the first network, even if it is also on the second network.

A solution to the technical problem posed is characterized, according to a first object of the present invention, in that said method comprises the steps according to which: the first telecommunications network is defined as having priority over the second telecommunications network, when the module d subscriber identification is identified in the second telecommunications network, it is regularly checked whether the mobile station enters the coverage field of the first telecommunications network, said verification being done by regularly resetting the mobile station, the mobile station enters the coverage of the first telecommunications network, the subscriber identification module automatically identifies itself to the first telecommunications network under its first identity, without intervention by the subscriber.

According to a second object of the present invention, this solution is characterized in that the subscriber identification module further comprises:

means for defining the first telecommunications network as a priority with respect to the second telecommunications network, means for regularly checking whether the mobile station enters the coverage field of the first network when the subscriber identification module is identified with the second telecommunications network under its second identity, said checking means being able to regularly reset the station mobile,

- Means for said subscriber identification module to automatically identify itself without intervention of the subscriber to the first telecommunications network under its first identity when the mobile station enters the coverage field of the first telecommunications network.

Thus, as will be seen in detail below, the method of the invention allows this concept of roaming to be managed transparently to the subscriber. The subscriber's telecommunications network is defined as having priority over the second network. Thus, when the subscriber identification module is identified in the coverage area of the second network and it passes into the coverage area of the first network, said module identifies itself automatically with respect to the priority network, that is to say - say in relation to the first network, even if it is still within the coverage of the second network. There is no user intervention.

The description which follows with reference to the appended drawings, given by way of nonlimiting example, will make it clear what the invention consists of and how it can be implemented.

Figure 1 is a diagram of a country's network coverage. FIG. 2 is a diagram of a mobile station located in the coverage fields of different networks in the country of FIG. 1. FIG. 3 is a diagram of the mobile station of FIG. 2. In Figure 1 is shown the territory of a country 10 and its network coverage. The territory of country 10 is covered by at least two mobile telephone telecommunications networks, a first network 11 and a second network 12 managed by two respective operators and covering two respective geographic areas. In the example of FIG. 1, said geographic areas have a region 13 of intersection.

A telecommunications network in mobile telephony, based for example on the GSM or DCS standards, generally comprises a mobile switching center MSC, a nominal location register HLR and a home location register VLR. The nominal location register HLR, on the one hand, stores characteristics of each subscriber such as the IMSI of the subscriber used by the network or a directory number of the MSISDN subscriber corresponding to the number of his station mobile by which it can be called, and, on the other hand, for each subscriber, said HLR recorder stores the home location recorder VLR where the subscriber is registered, even in the case where a subscriber connects to a other network. Each IMSI identity is made up of an MCC code for the subscriber's home country, an MNC code for the subscriber's nominal network and an HLR register code for the subscriber's nominal location within his network. Thus, these three fields make it possible to determine, in a unique way in the world, the nominal network of the subscriber as well as his HLR recorder of nominal location. The switching center MSC dialogues with the home location register VLR to manage the mobility of the subscribers, while the said VLR recorder stores subscription data of the subscribers present in a geographical area also called location area. The data stored by said VLR home location recorder is similar to HLR nominal location recorder data, but only concerns mobile subscribers present in the area under consideration.

A location area is identified by an area identification means LAI. This means is composed of an MCC code for the country in which said location zone is located, a MNC code for the network covering said zone and finally an LAC code for identifying said zone.

A subscriber, owner of a MS mobile station, has a first subscriber account, called nominal account, managed by the operator of the first telecommunications network 1 1 and a second subscriber account, called partner account, managed by a partner operator. The partner operator has an international roaming agreement with a third operator managing the second network 12 or managing the second network itself. The first network 1 1 is called the nominal network of the first subscriber account. The partner account is linked to a partner network of the partner operator called the nominal network of the partner account (not shown).

We are interested in the case where the second network is managed by the third operator. Of course, the partner operator may have other international roaming agreements with other operators managing other networks.

The subscriber's mobile MS station includes a subscriber identification SIM module as well as a transceiver called a mobile device. This module is described in particular in the GSM 1 1.1 1 and GSM 1 1.14 standards, published by ETSI, the content of which is incorporated into this presentation by citation of reference.

Said subscriber identification SIM module comprises in particular a control element 21 (for example a central processing unit or CPU), a rewritable memory 23 (for example EEPROM), a non-rewritable memory 24 (ROM), and a contact block 25 intended for an electrical connection with the mobile MS station.

Said SIM module comprises, on the one hand, two means corresponding to two respective identities IMSI l and IMSI2, and, on the other hand, means LOCI for locating said station MS as well as means PLMN2 for selecting networks. These means are in particular files included in the rewritable memory 23 of said module. The two identities correspond respectively to the nominal account and the aforementioned partner account. The PLMN2 network selection means is linked to the partner account. In our example, said means PLMN2 for network selection is also linked to the subscriber account.

When the subscriber turns on his MS mobile station, an initialization phase starts. This phase of initialization of the mobile MS station essentially comprises a phase of initialization of the SIM module and a phase of registration on a selected network.

The initialization phase of the SIM module essentially comprises the steps according to which:

- the MS mobile station reads the active IMSI identity from the subscriber identification SIM module, the MS mobile station searches for and selects an accessible network, the search being carried out first on the old network on which the MS mobile station was registered thanks to a temporary TIMSI identity found in the LOCI locating means and on the nominal network of the active identity, then thanks to the PLMN2 means for selecting networks.

The recording phase notably includes the step according to which: - the MS mobile station registers on the selected network, which corresponds to an identification by means of the IMSI identity active on said selected network.

The temporary TIMSI identity is the identity that was used and stored in the VLR home location recorder where the subscriber is registered, before switching off or removing the SIM module from a mobile.

The active IMSI identity is the identity whose corresponding file is selected in the SIM module. During a recording, the station MS sends to the switching center MSC, a location request. This can determine, from the active IMSI identity, the nominal location recorder

HLR on which said station depends. The switching center MSC launches an authentication procedure in order to verify the legality of the active identity. Said HLR subsequently sends all the characteristics relating to the station MS to the home location register VLR and stores the identity of said home recorder VLR. The MS mobile station stores the identity LAI of the location area in which it is located, in the LOCI location means of its subscriber identification SIM module as well as its temporary identity TIMSI. This storage corresponds to an update of the location information.

A mobile MS station can be located either in the coverage field of the first network 11, or in the coverage field of another network, here the second network 12. In the example in the figure, the two networks having a intersection region 13, the mobile MS station can also be in said region 13.

As shown in Figure 2, it is expected that when the MS mobile station is in the coverage area of the second network 12, the subscriber identification SIM module identifies with the second network 12 telecommunications under its second IMSI2 identity and thus uses its partner account, said second IMSI2 identity corresponding to said account. In this case, said second IMSI2 identity is the temporary identity. As described below, this is only valid when the MS mobile station is no longer in the field of the first network 11.

It is also expected that when the mobile MS station enters the scope of the first telecommunications network 1 1, the subscriber identification SIM module automatically identifies itself to the first telecommunications network 1 1 under its first identity IMSI l, without intervention of the subscriber, even if the MS mobile station is still in the field of the second network 12.

When the subscriber identification SIM module is identified in the second telecommunications network, it is regularly checked whether the mobile station M S falls within the coverage field of the first telecommunications network 11. The frequency of verification can be periodic or random. Preferably, the verification is done every fifteen minutes. The verification is done by regularly resetting the MS mobile station. The mobile MS station always remains on, therefore, said reset is transparent vis-à-vis the subscriber.

The verification is triggered by a command or a program included in the subscriber identification SIM module. Said program includes a reset command, for example the REFRESH command described in the GSM standard 1.14 published by ETSI. Advantageously, prior to said reinitialization, the content of the LOCI locating means of said SIM module is erased.

Of course, said verification based on a reset is only a means for said identification SIM module to identify itself. automatically without intervention of the subscriber with the first network. Said SIM module may include other means such as specific programs not using reset, but leading to the same result as the previous verification. During the reset, we read the active identity in the module

SIM. Said identity is the IMSI2 identity corresponding to the partner account. Thereafter, as described previously, the reinitialization of the mobile MS station makes it possible to launch a search which begins on the old network on which the mobile MS station was registered. The search is done using LOCI localization. The content thereof having been deleted, the search continues with the network corresponding to the active identity, here the second IMSI2 identity. The corresponding network is the partner network. Since the MS mobile station is not in said network, the search continues on the other networks.

It will be noted that this search being triggered, it is carried out when the second network 12 is no longer accessible, or when said network no longer optimally covers the location area in which the mobile station MS is located, as in the case of the region 13 of intersection shown in FIG. 2, or even when the mobile MS station is in the coverage field of the second network 12 and that said coverage is optimal.

The search continues thanks to the PLMN2 network selection means included in the subscriber identification SIM module. This means comprises a set of identities Ri of networks accessible to said mobile station MS, said identities being placed in said means PLMN2 in order of preference of use. For example, identities are names of networks or MNC codes of networks, each code can be associated with a country code. The PLMN2 file is the means to define the first network 1 1 of telecommunications as a priority with respect to the second telecommunications network and to the other networks which may be accessible by the mobile MS station.

As shown in Figure 3, it is expected that the first network 1 1 is placed first in this means PLMN2 selection. Thus, for the partner account, the first telecommunications network 1 1 is defined as having priority with respect to the second telecommunications network 12, and with respect to all those which could be accessible in country 10. The priority network, here the first network 1 1 telecommunications, is automatically chosen when the MS mobile station is within the coverage of said network

1 1 ie as soon as it enters said field of said first network

1 1, even if said mobile MS station is still in the coverage field of the second network 12. The partner account is subsequently registered in the first network 1 1 by means of the second identity IMSI2. A temporary TIMSI identity is assigned to it. The station MS is thus registered in said first network 1 1. The location information located in the LOCI locating means is updated and thus comprises the means LAI for locating the area covered by the first network 1 1 called nominal network .

Thereafter, the regular verification consisting in verifying whether the mobile station M S falls within the coverage of the first telecommunications network 11 is no longer triggered. Note that when a conversation is in progress, we avoid triggering this check so as not to cut the conversation.

And, likewise, the verification is preferably triggered only every fifteen minutes. However, in order to avoid the additional costs due to the use of the partner account on the nominal network, it is planned to switch to the nominal account corresponding to the first network 1 1.

In a first step, after an update of the LOCI locating means, it is verified that the mobile MS station has identified with the first network 11 by means of its second identity IMSI2. The verification is done using LOCI location means of the SIM module.

The codes of the LOCI location means are compared with those of the first IMSI l identity, namely the MNC codes of the network and MCC of the country. The first network 1 1 is used when the codes are equivalent. Then, it is checked that the second IMSI2 identity is well recorded.

In a second step, after verifying that the subscriber is using his partner account on the nominal network 11, the first identity IMSI1 is activated.

For this, the invention provides that the subscriber identification SIM module includes means ACTIV for activating an IMSI identity of the SIM module. This means is in particular a program included in the memories 24 not rewritable or 23 rewritable of the SIM module. In the case of FIG. 3, it is in the memory 24 which cannot be rewritable. In a nonlimiting embodiment, said activation means ACTIV corresponds to a selection of the file corresponding to an IMSI identity and to an activation of all the attached files. Thanks to the ACTIVating means ACTIVATION, the first IMSI identity 1 corresponding to the nominal account is activated, while that which was previously activated, that is to say the second IMSI2 identity, is deactivated.

Then, an initialization phase of the mobile MS station transparent to the subscriber is restarted, by means of the command REFRESH initialization, as described above. During this phase, authentication takes into account the active identity of the module

SIM. The first IMSIl identity corresponding to the nominal account which is activated is thus retained for authentication. The search begins on the old network on which the mobile MS station was registered thanks to the temporary identity TIMSI found in the locating means LOCI. The old network is the first network 1 1. This being accessible, it is selected and the recording is done by means of the active identity IMSIl. Thus the nominal account is again used on the first telecommunications network 11 and the mobile station MS is registered with its first identity IMSI 1.

Note that prior to said reinitialization, the content of the LOCI locating means can be deleted. In this case, the search will not stop at the old network, but will continue on the nominal network of the first IMSIl identity which is the first network.

1 1 which will be selected.

The average time for checking and switching accounts is advantageously low and is less than a minute. This avoids blocking incoming or outgoing calls as in the case of a manual change of accounts and networks made by the subscriber.

Following the same principle as above, it is expected that the mobile MS station will leave the coverage area of the first telecommunications network 11. Subsequently, the subscriber identification SIM module identifies itself automatically with the second telecommunications network 12 under its second IMSI2 identity, without intervention by the subscriber. The subscriber must not use a menu, must not change the SIM module or must not enter a code for this identification to take place. It takes place without said subscriber being the initiator. To this end, the subscriber identification SIM module includes a CNTRL means for controlling loss of network coverage. This means is in particular a program included in the memories 24 not rewritable or 23 rewritable of the SIM module. When the mobile MS station leaves a network, said station generally updates the information of the LOCI location means. The updated information is, for example, the temporary TIMSI identity which is erased or a data item indicating coverage.

Also, a first non-limiting embodiment of said control means consists in comparing the codes of the LOCI means of localization and of the active IMSI l identity, namely the codes MNC of the network and MCC of the country. One difference indicates a loss of network coverage. A second embodiment consists in verifying a data of indication of coverage being found in the means LOCI of localization. This indicates whether the network coverage is still active. In these two modes, said control means CNTRL is triggered by said SIM module, after each update of the information of the location means LOCI by the mobile station MS. A third embodiment consists in that the control means CNTRL is triggered periodically by said SIM module, for example every fifteen minutes. In a first step, said means CNTRL requests the mobile MS to send it location information corresponding to the current location area, and, in a second step, compares said information with that of the first active IMSI1 identity. One difference indicates a loss of network coverage. In this case, the CNTRL control means uses in particular an PROVIDELOCALINFO information command described for example in the GSM 1 1.14 standard published by ETSI. Generally, when the coverage of a network is lost and the mobile station MS enters a second network, it tries to register with this second network 12 with its active identity, here the first identity IMSI 1. However, having no roaming agreement with this second network 12, said mobile MS station cannot use the second network 12. The latter prohibits the registration of said mobile MS station. Consequently, the MNC code of said second network

12 is included in a means of prohibiting FPLMN networks (not shown). This means of prohibiting FPLMN networks is in particular a file written in the rewritable memory 23 of the module.

In order, however, to be able to use this second network 12, when the loss of coverage of the first network 1 1 is noted, said SIM module triggers the ACTIV means of identity activation and thus activates the IMSI2 identity corresponding to the partner account. The second network 12 is defined in the network selection means PLMN2, as a priority with respect to the other networks and secondary with respect to the first network 1 1. The MNC code of the second network 12 is thus placed second in the PLMN file.

Then, the mobile MS station is reset transparently to the user, in particular by means of the reset command REFRESH. The network search is done first by means of LOCI localization. Either we find that the old network is the first network 1 1 thanks to the temporary identity TIMSI, or said identity has been deleted. The first network 1 1 is no longer accessible, in both cases the search continues on the nominal network of the IMSI2 partner account, ie the partner network, but does not succeed because said network does not cover the area in which it is located. the MS mobile station. Subsequently, the search is made by means of the PLMN2 network selection means, in priority on the first network 1 1, then on the second network 12. The first network no longer covering the zone where the mobile station MS is located, the partner account is then registered on the second network 12. The subscriber identification SIM module is thus identified with the second network 12, by means of its second identity IMSI2. The information of the LOCI location means having been updated, automatically after fifteen minutes, a regular check is triggered, said check making it possible to determine whether the MS mobile station falls within the coverage field of the first network 11, and thus immediately as seen previously. It will be noted that during the initialization phase of the SIM module, generally, a search is made in the means of prohibiting FPLMN networks corresponding to the active IMSI identity, in order to know the networks to which one cannot access. In a first embodiment, a means of prohibiting FPLMN networks is attached to each IMSI identity, for example a first means of prohibiting FPLMN networks 1 is attached to the first identity IMSI1 and a second means of prohibiting FPLMN2 is attached to the second IMSI2 identity. In a second embodiment, a single FPLMN prohibition means is attached to several IMSI identities, for example a single FPLMN prohibition means is attached to the first and second identities IMSI 1, IMSI2. In this second mode, in order to be able to use the second network 12, advantageously, it is provided that simultaneously with the activation of the second identity IMSI2 corresponding to the partner account, the call sign of the second network 12 is deleted in said means for prohibiting FPLMN networks.

Furthermore, it will be noted that generally a user of the mobile MS station can on his own initiative change the order of preference of use of the networks in the network selection means PLMN2.

It is thus possible not to find the first priority network 1 1 or the second network 12. Also, advantageously ^ each activation of a IMSI identity, simultaneously, in the PLMN2 network selection means, the first network 11 is given priority over the second network 12, and the second network 12 is priority over other networks that can cover the territory of the country 10. Thus, the network selection means PLMN2 first comprises at least the code MNC of the first network 1 1 and second at least the code MNC of the second network 12.

Of course, the invention is in no way limited to the description of the examples of implementation above. The scope of the invention extends to other embodiments in which, in particular, said subscriber identification SIM module can be identified with a multitude of networks which are defined on a priority scale in one or more means. PLMN for network selection or also said SIM module includes multiple IMSI identities corresponding to different subscriber accounts.

Claims

1 - Method for identifying a subscriber within a first (1 1) and a second (12) telecommunications network, according to which the subscriber has a mobile station (MS) provided with a subscriber identification module (SIM), said subscriber identification module comprising means for identifying with the first telecommunications network (1 1) under a first identity (IMSI 1) as well as means for identifying with the second telecommunications network (12) under a second identity (IMSI2), characterized in that said method comprises the steps according to which: the first telecommunications network (11) is defined as having priority over the second telecommunications network (12) ; when the subscriber identification module (SIM) is identified in the second telecommunications network (12), it is regularly checked whether the mobile station (MS) falls within the coverage of the first telecommunications network (11), said verification being done by regularly resetting the mobile station (MS), the mobile station (MS) enters the field of coverage of the first telecommunications network (1 1); - the subscriber identification module (SIM) identifies itself automatically with the first telecommunications network (1 1) under its first identity (IMSI l), without intervention by the subscriber.

2 - Method according to claim 1, characterized in that the subscriber identification module (SIM) identifies itself automatically with the first telecommunications network (1 1), and this, even if the mobile station (MS) is still within the coverage of the second network (12).

3 - Method according to any one of the preceding claims, characterized in that the verification is triggered by a command or a program included in the module

(SIM) subscriber identification, said program comprising a reset command (REFRESH).

4 - Method according to any one of the preceding claims, characterized in that it comprises an additional step according to which:

- prior to said reinitialization, the content of a locating means (LOCI) included in said module (SIM) is erased.

5 - Method according to any one of the preceding claims, characterized in that it comprises the additional steps according to which:

- The mobile station (MS) leaves the field of coverage of the first telecommunications network (1 1);

- the subscriber identification module (SIM) identifies itself automatically with the second telecommunications network (12) under its second identity (IMSI2), without intervention by the subscriber.

6 - Method according to claim 5, characterized in that the step of automatic identification of the module (SIM) with the second network (12) under its second identity (IMSI2) comprises the additional steps according to which:

- there is a loss of coverage of the first network (1 1),

- an identity activation means (ACTIV) is activated by said module (SIM) and the second identity (IMSI2) is thus activated, - said mobile station (MS) is reset.

7 - Method according to claim 6, characterized in that it comprises an additional step according to which:

- Prior to said reinitialization, the second network (12) is defined in a means (PLMN2) for selecting networks as priority over other networks and secondary over the first network (1 1).

8 - Method according to claim 6, characterized in that the loss of coverage is noted by means (CNTRL) of monitoring loss of coverage.

9 - A method according to claim 8, characterized in that the means (CNTRL) of loss of coverage control is triggered after each update of information from a locating means (LOCI) by the mobile station (MS). 10 - Method according to claim 8, characterized in that said control means (CNTRL) is triggered periodically by said SIM module.

11 - Method according to claim 10, characterized in that said control means (CNTRL) uses an information command (PROVIDELOCALINFO).

12 - Method according to any one of the preceding claims, characterized in that the step of automatic identification of the module (SIM) with the first telecommunications network (1 1) under its first identity (IMSI l) comprises the additional steps whereby :

- the subscriber identification module (SIM) identifies itself to the first telecommunications network (11) by means of the second identity (IMSI2), - it is verified that the subscriber identification module (SIM) has identified itself on the first network (1 1) by means of its second identity (IMSI2),

- the first identity is activated (IMSI 1), - a reinitialization phase of the mobile station (MS) is restarted. 13 - The method of claim 12, characterized in that the verification is done by means of location (LOCI) of the module (SIM). 14 - Method any one of the preceding claims, characterized in that the reset is transparent vis-à-vis the subscriber.

15 - Method according to any one of the preceding claims, characterized in that the first telecommunications network (11) is defined as having priority over the second telecommunications network (12) by means of network selection means (PLMN2) .

16 - Method according to any one of the preceding claims, characterized in that the initialization phase of the mobile station (MS) comprises a module initialization phase (SIM) and a recording phase on a network.

17 - Subscriber identification module (SIM) intended to be associated with a mobile station (MS), comprising:

- Means for identifying with a first telecommunications network (11) under a first identity (IMSI 1);

- means for identifying with a second telecommunications network (12) under a second identity (IMSI2); and characterized in that it further comprises: - means for defining the first telecommunications network (1 1) as a priority with respect to the second telecommunications network (12),

means for regularly checking whether the mobile station (M S) falls within the coverage of the first network

(11) when the subscriber identification module (SIM) is identified with the second telecommunications network (12) under its second identity (IMSI2), said verification means being able to regularly reset the mobile station (MS), - means for said subscriber identification module (SIM) to identify itself automatically without intervention of the subscriber to the first telecommunications network (1 1) under his first identity (IMSI 1) when the mobile station (MS) enters the coverage of the first telecommunications network (1 1).

18 - Subscriber identification module (SIM) according to claim 17, characterized in that the identification means are capable of identifying said subscriber identification module (SIM) automatically without intervention of the subscriber with the first network (1 1) telecommunications under its first identity (IMSIl) when the mobile station (MS) enters the field of coverage of the first telecommunications network (11), even if the mobile station (MS) is still in the field coverage of the second network (12).

19 - Subscriber identification module (SIM) according to one of claims 17 or 18, characterized in that said verification means are triggered by a command or a program included in the subscriber identification module (SIM), said program with a reset command

(REFRESH).

20 - Subscriber identification module (SIM) according to one of claims 17 to 19, characterized in that it comprises means for erasing the content of a locating means

(LOCI) included in the (SIM) module.

21 - Subscriber identification module (SIM) according to one of claims 17 to 20, characterized in that it comprises means for automatically identifying with the second network (12) under its second identity (IMSI2) without intervention of the subscriber.

22 - Subscriber identification module (SIM) according to one of claims 17 to 21, characterized in that it comprises means (ACTIV) for activating an identity (IMSI). 23 - Subscriber identification module (SIM) according to one of claims 17 to 22, characterized in that it includes means (PLMN2) for selecting networks being able to define the second network (12) as priority over to other networks and secondary to the first network (1 1). 24 - Subscriber identification module (SIM) according to one of claims 17 to 23, characterized in that it comprises means (CNTRL) for controlling loss of network coverage.

25 - Subscriber identification module (SIM) according to claim 23, characterized in that the means (CNTRL) of loss of coverage control is capable of being triggered after each update of information from a means (LOCI) location by the mobile station (MS).

26 - Subscriber identification module (SIM) according to claim 23, characterized in that the means (CNTRL) of loss control coverage is adapted to be triggered periodically by said SIM module.

27 - Subscriber identification module (SIM) according to claim 25, characterized in that the means (CNTRL) for controlling loss of average coverage (CNTRL) uses an information command (PROVIDELOCALINFO).