Abstract:
A method for performing a switch from a first mobile network to a second mobile network by a mobile terminal comprising a secure element includes the following steps: attaching to the first mobile network using a first subscription profile; downloading a second subscription profile from a subscription management server including a command script defining a sequence of commands; attaching to the second mobile network; and executing the sequence of commands defined by the command script.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to mobile communications in general and in particular to methods and devices for performing a switch from a first subscription profile for attaching to a first mobile network to a second subscription profile for attaching to a second mobile network by a mobile terminal comprising a secure element, such as a subscriber identity module (SIM), an eUICC/UICC or the like. 
       BACKGROUND OF THE INVENTION 
       [0002]    Communicating by means of a mobile terminal, such as a mobile phone, via a public land mobile network (PLMN; also referred to as a mobile or cellular communications network herein) operated by a mobile network operator (MNO) generally requires the mobile terminal to be equipped with a secure element for securely storing data uniquely identifying the user of the mobile terminal (also called subscriber). For instance, in the context of a mobile terminal configured to communicate according to the Global System for Mobile Communications (GSM), currently the world&#39;s most popular standard for mobile communications systems, the secure element is called a subscriber identity module (SIM) and is usually provided in the form of a smart card. According to the GSM standard, the technical features of which are defined by a large number of interrelated and mutually dependent specifications published by the ETSI standardization organization, the SIM contains subscription credentials for authenticating and identifying the user of the mobile terminal, including in particular an International Mobile Subscriber Identity (IMSI) and an authentication key K i . These subscription credentials are generally stored on the SIM as part of a subscription profile by the SIM manufacturer/vendor or the MNO during a SIM personalization process prior to providing the user of the mobile terminal with his SIM. A non-personalized SIM is generally not suited for use in a mobile terminal, i.e. using the services provided by a PLMN with a non-personalized SIM without a subscription profile is not possible. 
         [0003]    One particular field of application of secure elements, such as SIMs, eUICCs, UICCs and the like, which is expected to grow rapidly in the future is M2M (machine-to-machine) communication, i.e. the communication between machines over a cellular communications network without human intervention, also called the Internet of things. In M2M communication data is automatically transmitted between many different types of machines equipped with a secure element in the form of a M2M module, such as TV systems, set top boxes, vending machines, vehicles, traffic lights, surveillance cameras, sensor devices, and the like. It is foreseeable that at least for some of these devices it will not be possible or at least very difficult to provide the secure element beforehand with a subscription profile, including for instance an IMSI. This is because in a lot of M2M devices the secure element will most likely be implemented in the form of a surface mounted chip or chip module without the possibility of providing the secure element with a subscription profile beforehand. Consequently, once in the field, these M2M devices and their non-personalized secure elements generally require the provision of a subscription profile over-the-air. 
         [0004]    When using the services provided by a MNO, in particular communicating via the PLMN provided by the MNO, the user of a mobile terminal is usually charged a certain monthly fee by the MNO. If the mobile user wants, for instance due to a lower monthly charge and/or superior services, to change to a different MNO, he generally has to manually replace the SIM provided by the current MNO and containing the subscription profile necessary for attaching to the PLMN of the current MNO by the SIM provided by the new MNO and containing the subscription profile necessary for attaching to the PLMN of the new MNO. Certainly, it would be easier for the user, if instead of this conventional process of switching to a new MNO by manually replacing the SIM it would be possible to use one and the same secure element in the form of a SIM that can be “reprogrammed” over-the-air. 
         [0005]    Conventional methods are known for downloading a target subscription profile over-the-air onto a secure element with an already existing subscription profile and performing a switch from the already existing subscription profile to the target subscription profile associated with a target mobile network. Moreover, it is known to confirm the successful finalization and switch to the target mobile network by sending SMS, USSD and/or BIP messages from the mobile terminal to a subscription management backend system. However, in some case these communication means for finalizing and confirming a mobile network switch are not available at all, for instance, because SMS messages cannot be used on the target mobile network due to no credit yet, or should be reduced to a minimum for cost reasons. There is, therefore, a need for improved methods and devices for performing a switch from a first mobile network to a second mobile network by a mobile terminal comprising a secure element, such as a subscriber identity module (SIM), an eUICC/UICC or the like, and, in particular, for improved methods and devices for confirming the successful finalization of such a switch to a subscription management backend system. 
       SUMMARY OF THE INVENTION 
       [0006]    The above object is achieved according to the present invention by the subject-matter of the independent claims. Preferred embodiments of the invention are defined in the dependent claims. 
         [0007]    According to a first aspect the invention provides for a method for performing a switch from a first mobile network to a second mobile network by a mobile terminal comprising a secure element. The method comprises the following steps: attaching to the first mobile network using a first subscription profile; downloading a second subscription profile from a subscription management server; downloading a command script defining a sequence of commands from the subscription management server; attaching to the second mobile network using the second subscription profile; and executing the sequence of commands defined by the command script. 
         [0008]    According to preferred embodiments of the invention, the command script is downloaded as part of the second subscription profile. 
         [0009]    Preferably the step of downloading the command script comprises the additional step of checking the integrity of the command script. 
         [0010]    According to preferred embodiments of the invention, the step of checking the integrity of the command script comprises the additional step of sending a confirmation message to the subscription management server confirming that the command script received from the subscription management server is integer. Preferably the confirmation message is a SMS message. 
         [0011]    Preferably the step of executing the sequence of commands comprises the additional step of sending a confirmation message to the subscription management server confirming that the sequence of commands defined by the command script has been executed successfully. Preferably the confirmation message is a SMS message. 
         [0012]    According to preferred embodiments of the invention, the receipt of the confirmation message by the subscription management server triggers the additional step of instructing the secure element to switch to the second subscription profile and to attach to the second mobile network. 
         [0013]    Preferably the method comprises the additional step of repeating the execution of the sequence of commands defined by the command script from the beginning or returning to the first subscription profile, in case the sequence of commands defined by the command script was not executed successfully. 
         [0014]    According to preferred embodiments of the invention, the method includes the additional step of informing the second mobile network about the download of the second subscription profile by the secure element and providing the second mobile network with the subscription credentials of the second subscription profile for the second mobile network to be able to allow the secure element to attach to the second mobile network using the second subscription profile. 
         [0015]    Preferably the step of downloading the second subscription profile comprises the additional step of storing the command script in a memory of the secure element such that the secure element has access thereto, once the secure element has attached to the second mobile network using the second subscription profile. 
         [0016]    According to preferred embodiments of the invention, the first mobile network and/or the second mobile network are operated according to the GSM standard. 
         [0017]    Preferably the first subscription profile is a provisional subscription profile that is stored on the secure element during the manufacturing and/or personalization process of the mobile terminal and/or the secure element. 
         [0018]    According to a second aspect the invention provides for a secure element configured to perform the steps of the method according to the first aspect of the invention. 
         [0019]    Preferably, the secure element is a subscriber identity module (SIM) for authentication/identification of a subscriber in the mobile network. Such a SIM communicates with the mobile terminal via a card reader therein and can be removed in principle from the mobile terminal to be either replaced by a different SIM and/or used in a different mobile terminal. Alternatively, the secure element is an integral part of the mobile terminal such as a hard-wired chip module. Such embedded secure elements are known, for instance, as embedded Universal Integrated Circuit Cards (eUICCs). Preferably, the secure element supports storage of multiple subscription profiles which may be associated with different MNOs. Generally, only one subscription profile is active at a time. 
         [0020]    According to a third aspect the invention provides for a mobile terminal containing a secure element according to the second aspect of the invention. 
         [0021]    The mobile terminal according to the present invention comprises means for communicating with a cellular communications network, in order to receive a new subscription profile. Preferably, the mobile terminal is implemented in form of a smart phone, a tablet PC, a notebook, a PDA, or the like. Alternatively the mobile terminal can be a multimedia device such as digital picture frame, audio equipment, a TV system, a set top box, an e-book reader and so on. By way of example, the term “mobile terminal” also includes any kind of machinery, like vending machines, vehicles, smart-meters and the like that are configured to communicate via a cellular communications system in the context of a M2M system. 
         [0022]    According to a fourth aspect the invention provides for a subscription management server configured to interact with the secure element according to the second aspect of the invention according to the method according to the first aspect of the invention. 
         [0023]    These and other features, characteristics, advantages, and objects of the invention will be clear from the following detailed description of preferred embodiments, given as a non-restrictive example, under reference to the attached drawings. The person skilled in the art will appreciate, in particular, that the above preferred embodiments can be combined in several ways, which will result in additional advantageous embodiments that are explicitly supported and covered by the present invention. In particular, the person skilled in the art will appreciate that the above described preferred embodiments can be implemented in the context of the different aspects of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  shows a schematic overview of a mobile communications system illustrating different aspects of the present invention; and 
           [0025]      FIG. 2  shows a diagram illustrating a method for performing a mobile network switch from a first mobile network to a second mobile network of the mobile communications system of  FIG. 1  according to a preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]      FIG. 1  shows schematically the components of a communications system  10  as well as some of the communication channels or links between the components of this system  10  that illustrate different aspects of the present invention. Although the below detailed description will refer to a “mobile” terminal, the person skilled in the art will appreciate that the present invention can be advantageously implemented in the context of any kind of terminal that is configured to communicate via a mobile or cellular communications network. In other words, the attribute “mobile” used herein refers to the ability of a terminal to communicate via a mobile or cellular communications network (or short mobile network), also including IP based mobile communication networks. 
         [0027]    An exemplary mobile terminal  12  is shown in  FIG. 1  including a secure element  14  for securely storing and processing data that uniquely identifies the mobile terminal  12  and/or its user, i.e. the subscriber. As indicated in  FIG. 1 , the mobile terminal  12  preferably is a mobile phone, smart phone or a similar device. The person skilled in the art will appreciate, however, that the mobile terminal  12  according to the present invention can be implemented in the form of other devices as well, such as a tablet or notebook computer, a TV system, a set top box, a vending machine, a vehicle, a surveillance camera, a sensor device and the like. 
         [0028]    According to preferred embodiments of the invention the secure element  14  is configured as an eUICC or UICC with a SIM application running thereon, i.e. a secure element that can be mounted in the mobile terminal  12  and used in cellular communications systems for unique and secure subscriber identification as well as for the provision of different special functions and value-added services. Alternatively, the secure element  14  could be configured as a removable subscriber identity module (SIM), the SIM currently being the most popular type of secure element. The person skilled in the art will appreciate, however, that other types of secure elements that, depending on the underlying generation and type of cellular communications system standard, are designated as USIM, R-UIM, ISIM and the like, are also encompassed by the present invention. Moreover, the secure element  14  could be a M2M module or a Trusted Execution Environment (TEE) implemented as part of the mobile terminal  12 . 
         [0029]    The mobile terminal  12  is configured to communicate via the air interface (or radio link) with a first cellular communications network or public land mobile network (PLMN)  30  or a second cellular communications network or public land mobile network (PLMN)  40  of a mobile communications system  20 . Preferably, the first PLMN  30  (also referred to herein as the provisioning PLMN  30 ) is operated by a first mobile network operator (MNO) and the second PLMN  40  (also referred to herein as the target PLMN  30 ) is operated by a second mobile network operator (MNO). Preferably, the provisioning PLMN  30  and the target PLMN  40  can be accessed from substantially the same physical location. According to preferred embodiments the provisioning PLMN  30  and/or the target PLMN  40  are operated according to the GSM standard. 
         [0030]    In the following, preferred embodiments of the invention will be described in the context of mobile or cellular communications networks according to the standards of the Global System for Mobile communication (GSM), as specified in a number of specifications provided by ETSI. However, the person skilled in the art will appreciate that the present invention may be advantageously applied in connection with other cellular communications systems as well. Such systems include third-generation cellular communications systems (3GPP), such as the Universal Mobile Telecommunications System (UMTS), and next generation or fourth-generation mobile networks (4G), such as Long Term Evolution (LTE), as well as other cellular communications systems. 
         [0031]    As is well known to the person skilled in the art, a PLMN configured according to the GSM standard generally comprises a base station subsystem consisting of one or more base transceiver stations that define respective cells of the PLMN and are connected to a base station controller. Generally, the base station controller is one of several base station controllers that communicate with a common mobile switching center (MSC). Often, a local database called Visitor Location Register (VLR) for keeping track of the mobile users currently located within the cells covered by a MSC (i.e. the MSC service area) is incorporated in the MSC. The MSC provides essentially the same functionality as a central office switch in a public-switched telephone network and is additionally responsible for call processing, mobility management, and radio resource management. The MSC is further in communication with a home location register (HLR), which is the primary database of the PLMN that stores information about its mobile users required for authentication. To this end, the HLR generally is in communication with an authentication center (AUC). The person skilled in the art will appreciate that although the above described components of a conventional GSM system may have different names in different or consecutive standards for mobile communications networks, the underlying principles used therein are substantially similar and, therefore, compatible with the present invention. 
         [0032]    As is known to the person skilled in the art, the communication means between the above described components of a PLMN may be proprietary or may use open standards. The protocols may be SS7 or IP-based. SS7 is a global standard for telecommunications defined by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T). The standard defines the procedures and the protocols by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wired call setup, routing and control. The SS7 network and protocol are used for e.g. basic call setup, management, wireless services, wireless roaming, and mobile subscriber authentication, i.e. enhanced call features providing for efficient and secure worldwide telecommunications. How the network elements are grouped or left separate and the interfaces—whether proprietary or open—between these elements are left to the MNO. 
         [0033]    Of the above described components of a PLMN only the following ones are shown in the schematic drawing of  FIG. 1  for ease of explanation: an exemplary base transceiver station  32  and a HLR  34  for the provisioning PLMN  30  and an exemplary base transceiver station  42  and a HLR  44  for the target PLMN  40 . The provisioning PLMN  30  and the target PLMN  40  are each at least in temporary communication with a subscription management server  50 , as will be described in more detail further below. The provisioning PLMN  30  and/or the target PLMN  40  moreover could each comprise a SMS-C (Short Message Service Center) for storing, forwarding, converting and delivering SMS messages or be connected to a common SMS-C. 
         [0034]    As can be taken from the enlarged view of the secure element  14  in  FIG. 1 , the secure element  14  preferably comprises a central processing unit (CPU)  15 . Preferably, the CPU  15  is configured such that at least one subscription management application  16  (SM applet) can be executed on the CPU  15  providing for some of the features that will be described in the context of  FIG. 2  in more detail further below. The subscription management application  16  could be implemented, for instance, as a Java Applet. For providing an execution environment for the subscription management application  16  a secure element operating system (not shown in  FIG. 1 ) is preferably implemented on the CPU  15 . 
         [0035]    Moreover, the secure element  14  preferably comprises a memory unit  17 , which preferably is implemented as a non-volatile, rewritable memory unity, e.g., a flash memory. As can be taken from  FIG. 1 , a first subscription profile (SUB)  18   a  is stored in the memory unit  17  of the secure element  14 . This first subscription profile  18   a  comprises data that allow the secure element  14  and the mobile terminal  12  to attach to the provisioning PLMN  30 , i.e. data, such as subscription credentials, a MNO specific authentication algorithm, and the like. Preferably, at least parts of the memory unit  17  of the secure element  14  are configured to securely store the data therein, for instance any subscription credentials to be kept secret, such as an International Mobile Subscriber Identity (IMSI) and/or an authentication key K i , that are part of the first subscription profile  18   a.  As indicated in  FIG. 1 , the memory unit  17  preferably provides several “slots” for accommodating additional subscription profiles, such as a second subscription profile (SUB)  18   b , which is preferably provided by the subscription management server  50  according to the process shown in  FIG. 2  and described in more detail further below. 
         [0036]    Preferably, the first subscription profile  18   a  is stored in the memory unit  17  of the secure element  14  during the manufacturing and/or personalization process of the mobile terminal  12  and/or its secure element  14 . Especially in the context of this preferred embodiment it is conceivable that the first subscription profile  18   a  is merely a provisional subscription profile only providing for basic services that allow the secure element  14  and mobile terminal  12  to communicate with the subscription management server  50  via the provisioning PLMN  30  and to download a more complete subscription profile providing for additional services, such as the second subscription profile  18   b  shown in  FIG. 1 . As a provisional subscription profile, such as the first subscription profile  18   a  shown in  FIG. 1 , generally provides only a limited functionality, the user of the mobile terminal  12  generally will be enticed to change to a more complete subscription profile providing for additional services, such as the second subscription profile  18   b  shown in  FIG. 1 . 
         [0037]    The operation of the SM server  50  in combination with the other elements of the communications system  10  shown in  FIG. 1  will now be described in the context of a preferred embodiment of the invention under further reference to  FIG. 2  for the case where in the beginning only the provisional subscription profile  18   a  is present on the secure element  14 . From the following detailed description the person skilled in the art will appreciate, however, that the present invention can be also advantageously used in the case where in addition to the provisional subscription profile  18   a  also the target subscription profile  18   b  (and possibly other subscription profiles) is already present on the secure element  14 . 
         [0038]    In step S 1  of  FIG. 2  the secure element  14  attaches to the provisioning PLMN  30  using its provisional subscription profile  18   a.  Preferably, this attachment is done according to the conventional GSM challenge response authentication procedure well known to the person skilled in the art. Having successfully attached to the provisioning PLMN  30  the secure element  14  in step S 2  of  FIG. 2  downloads the target subscription profile  18   b  from the SM server  50  for attaching to the target PLMN  40  and utilizing the services provided thereby. 
         [0039]    Preferably as part of downloading the target subscription profile  18   b,  the SM server  50  provides the secure element  14  in step S 2  of  FIG. 2  with a command script, i.e. a sequence or list of commands, to be executed by the secure element  14  after the secure element  14  has successfully attached to the target PLMN  40  using the target subscription profile  18   b.  The person skilled in the art will appreciate, however, that the SM server  50  could provide the secure element  14  with the command script in a separate step, i.e. the command script could be downloaded from the SM server  50  in a separate step. The command script could include commands for erasing the provisional subscription profile  18   a  in the non-volatile memory  17  of the secure element  14 , unlocking applications implemented on the secure element  14  and/or the mobile terminal  12 , unlocking a PIN number and the like. Preferably, the command script provided by the SM server in step  2  of  FIG. 2  is stored in a part of the memory  17  such that the SM applet  16  has access thereto, once the provisional subscription profile  18   a  is no longer active and the target subscription profile  18   b  has become the active subscription profile. 
         [0040]    In step S 3  of  FIG. 2  the secure element  14 , preferably by means of the SM applet  16 , checks that the command script it has received in step S 2  of  FIG. 2  is complete and has not been tampered with, for instance, by calculating a checksum thereof. This checksum could also include the target subscription profile  18   b  downloaded along with the command script in step S 2  of  FIG. 2 . In case the checksum computed by the secure element  14  is not equal to a reference checksum provided by the SM server  50  in step S 2  of  FIG. 2 , the secure element  14  could request the SM server  50  to repeat step S 2  of  FIG. 2 . The person skilled in the art is aware of many different available means to check the integrity of the data transmitted from the SM server  50  to the secure element in step S 2  of  FIG. 2 , such as hash functions and message authentication codes, and/or, if necessary, to protect this data by encryption, so that these means will not be described in greater detail herein. 
         [0041]    Having checked the integrity of the command script in step S 3  of  FIG. 2 , the secure element  14  preferably sends a confirmation message in step S 4  of  FIG. 2  to the SM server  50  confirming that the integrity of the command script it has received has not been tampered with, i.e. that the command script is integer. Preferably, the receipt of this confirmation message triggers the SM server  50  to instruct the secure element  14  to switch to the target subscription profile and to attach to the target PLMN  40 . Alternatively, the switch to the target subscription profile can be triggered by the secure element  14  itself or a user interaction via the mobile terminal  12 . Consequently, in step S 5  of  FIG. 2  the secure element  14  deactivates the provisional subscription profile  18   a,  activates the target subscription profile  18   b  and attaches to the target PLMN  40  using the target subscription profile  18   b.  This means, as the person skilled in the art will readily appreciate, that any subsequent communication between the secure element  14  and the SM server  50  is no longer via the provisioning PLMN  30 , but via the target PLMN  40 . 
         [0042]    In step S 6  of  FIG. 2  the secure element  14  executes the commands of the command script provided by the SM server in step S 2  of  FIG. 2  via the provisioning PLMN  40 . As already mentioned above, the command could include commands for removing the provisional subscription profile  18   a  on the memory unit  17 , unlocking certain applications on the secure element  14  or the mobile terminal  12  and the like. 
         [0043]    Only after all of the commands of the command script have been successfully executed, the secure element  14  sends a corresponding confirmation message to the SM server  50 , preferably in the form of a SMS message. Thus, this confirmation message proves to SM server  50  that the secure element  14  has successfully executed all commands of the command script and the SM server  50  can determine the state of the secure element  14  as well as the different subscription profiles located thereon. 
         [0044]    In case of any error before completion of the command script there is preferably a fall-back mechanism, such as repeating the execution of the command script from the beginning, returning to the provisional subscription profile  18   a,  for instance by deactivating the target subscription profile  18   b,  activating the provisional subscription profile  18   a  and attaching to the provisioning PLMN  30 . 
         [0045]    In light of the above detailed description the person skilled in the art will appreciate that modifications and/or additions can be made to the methods, devices and systems as described heretofore, which are to be considered to remain within the scope of the present invention as defined by the appended claims. 
         [0046]    For instance, the downloading of the subscription profile in step S 2  of  FIG. 2  could trigger the additional step (not shown in  FIG. 2 ) that the SM server  50  informs the target PLMN  40 , in particular the HLR  44  thereof, about the download of the target subscription profile  18   b  by the secure element  14  in order for the target PLMN  40  to perform any additional preparations that might be necessary for allowing the secure element  14  to attach to the target PLMN  40  using the target subscription profile  18   b,  such as registering the IMSI of the subscription profile in the HLR  44  of the target PLMN  40 .