Abstract:
A mechanism to allow provisioning and use of BYOD (Bring Your Own Device) for authorized access in the enterprise network through a  3 G/ 4 G/Wi-Fi access network is provided. A brokering entity in the mobile packet core is provisioned for each authorized employee with enterprise specific rules for security and steering of user traffic. An Enterprise Container is defined as entity on the User Equipment that is self-contained virtual machine with enterprise sanctioned applications. An intelligent mechanism for and steering of signaling and traffic from such BYOD devices to the brokering entity is defined. At any time by using the personal container or the default behavior of the user equipment the user can get mobile service as if the Enterprise Container did not exist. Further, when such employment relationship is terminated the user&#39;s BYOD needs to be restored to its pre-employment functionality.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/899,533, filed May 21, 2013, entitled Method and System for Selective and Secure Interaction of BYOD (Bring Your Own Device) with Enterprise Network Through Mobile Wireless Networks, the contents of which are incorporated herein in their entirety by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates generally to mobile wireless networks which include general packet radio service (GPRS) networks, universal mobile telecommunications system (UMTS) and long term evolution (LTE). Standardization work has also been done to interwork Wi-Fi radio with the above-said networks. Specifically, this disclosure relates to a method and system for allowing an Enterprise Container (or Enterprise Entity) within individually owned third generation (3G), fourth generation (4G) or Wi-Fi data devices (e.g., smart phones, tablets, personal computers (PCs), etc. which are also known as “Bring Your Own Device” (BYOD)) to securely interact with a trusted Enterprise Broker and eventually to an enterprise network itself using 3G, 4G or interwork Wi-Fi access. Enterprise policies decide which applications are allowed within the Enterprise Container on the BYOD. Based on these enterprise polices, the trusted Enterprise Broker is configured to steer the data to enterprise and external networks. 
       BACKGROUND 
       [0003]    GPRS and UMTS networks are an evolution of the global system for mobile communications (GSM) standards to provide packet switched data services to GSM mobile stations. Packet-switched data services are used for transmitting chunks of data or for data transfers of an intermittent or bursty nature. Typical applications for Third Generation Partnership Project (3GPP) packet services include Internet browsing, wireless e-mail, video streaming, credit card processing, etc. utilized by human users. 3GPP packet service could also be used to connect mobile devices to packet data networks owned by organizations such as government or enterprises.  FIG. 1  shows 3GPP networks (3G UMTS and 4G LTE) connecting mobile devices to the Internet as well as a private data network. It also shows interworking with Wi-Fi access. Referring to  FIG. 1 , mobile devices  102  and  103  are communicatively coupled to a packet core network  110 . For example, 3G/4G User Equipment (UE)  102  is coupled to packet core network  110  via a 3G Radio Access Network (RAN)  104  through, for example, node B (NB) and radio network controller (RNC)  105  and from there to the packet core node through the Serving GPRS Support Node (SGSN)  111 . The UE  102  is additionally coupled to the core network  110  via a corresponding LTE access network (e.g., evolved UMTS terrestrial RAN (Evolved Universal Terrestrial Radio Access Network (E-UTRAN)) node B (eNB)  106 . Finally the 3G/4G/Wi-Fi UE  103  is coupled to the packet core network  110  via RNC  105  or eNB  106  or via Wi-Fi access point  123 . In order to communicate to a data service located in other networks such as the Internet  120  and/or private network enterprise (or enterprise premise)  121 , UE data devices  102  and  103  have to go through packet core network  110 . Typically, packet core network  110  includes SGSN  111  for the 3G network or serving gateway (S-GW)  113  for the LTE network  106  and a gateway GPRS support node (GGSN)  112  for the 3G network or packet data network (PDN-GW)  114  for the LTE network. The packet core network  110  also has evolved packet date gateway (ePDG)  122  and 3GPP AAA Server  113  when Wi-Fi access  123  is interworked. SGSN  111 /S-GW  113  and GGSN  112 /PDN-GW  114  relay communications between UE  102  and UE  103  and a destination (e.g. Internet  120  and enterprise server  121 ). A typical packet core network  110  also includes a home location register (HLR) or home subscriber server (HSS)  117  storing subscription profile and a policy and charging rule function (PCRF)  118 . 
         [0004]    Today mobile technology has permeated through all walks of life and mobile phone penetration is more than 100% in most developed markets. Advances in content delivery (applications (Apps), streaming media, interactive), screen resolution (e.g., high-definition (HD)) and user interface (e.g., multi-touch, voice interactive), etc. have led to a new phenomenon called “device loyalty” where consumers make buying choices irrespective of their service providers and employers. Open mobile operation systems (OS) like Android® allow devices makers to create fairly sophisticated devices and bring them to market pretty quickly. People assemble their favorite set of applications as they see fit from the App stores and other sources. Some of these applications could have questionable origins since the Android® app store does not validate or qualify apps based on their behavior. 
         [0005]    Employers realize that mobile connectivity with employees leads to higher productivity. However, in the digital age where most of the knowhow, business strategies and product secrets exist as data, enterprises take security of their network quite seriously. In order to be productive the mobile employee will need access to the enterprise network. While enterprises can issue another mobile device to employees, it is neither cost effective nor productive. Rather it is burdensome since the mobile employee has not only to carry personal and enterprise devices all the time, but has to deal with logistics of partitioning their contacts and activities into personal and business which is ineffective and tedious if not impossible. This has lead to BYOD policies at the enterprise where employees bring their own mobile device and get enterprise&#39;s permission to access the corporate network. The decline of the enterprise specific Blackberry® is an indicator that this trend is strong. While it is convenient thing to do, it also opens up the enterprise network to attacks through variety of apps on the BYOD device. While this problem applies to all smartphones and mobile computing platforms, the problem is more acute for the Android® ecosystem, given the open nature of the Android® app store, the number of apps and the sheer number of devices running Android®. 
         [0006]    Traditional security solutions such as Internet Protocol security (IPSec) virtual private networks (VPNs) are impractical for mobile devices. IPsec encryption is computer intensive and has an adverse effect on battery life. Moreover, such VPN solutions typically rely on the end device being under protection of “always on” virus or malware scanning software that are connected to an enterprise monitor. It may not be practical for the user or the enterprise to continuously manage BYOD devices in the same manner. Therefore once malicious apps are on the smartphone because of intentional or unintentional user action, they could get root access by tricking the user and after that could get unauthorized access to the enterprise network even if the VPN was on. Therefore, traditional VPN solutions are not only inefficient but inadequate as well in the context of BYOD. 
         [0007]    Some have proposed virtualization based solutions whereby the mobile device runs personal and enterprise personality in a virtualized environment. The VMware®. Mobile Virtual Platform (MVP) is such an example. The enterprise personality is a self-contained virtual machine image and serves as the “enterprise container” for enterprise authorized apps and security policies. Just like in case of desktop virtualization, the enterprise container executes as a self-contained operating system. The personal and enterprise app containers may act as virtual machines (VM) on single user equipment (UE). The enterprise container is also expected to perform security procedures towards the enterprise and interact with the enterprise over the mobile network. Unfortunately, a traditional mobile network is not well suited for connecting to a large number of enterprises. The standard mechanism to interconnect a mobile network and an enterprise network is the Access Point Name (APN). The APN is part of the subscription profile. For APN-based enterprise access, the user first subscribes to that APN (i.e., the APN is put in subscriber profile at the HLR/HSS). In subsequent access requests, the UE includes the APN as part of the request. Upon receiving such a request, the SGSN/Mobility Management Entity (MME) first checks the subscription profile (downloaded from HLR/HSS) to confirm that the user is authorized to access the APN and upon success it passes this information to the Gateway GPRS Support Node (GGSN)/packet data gateway (P-GW). The P-GW typically has external networking setup to the enterprise for such an APN. It is obvious from this description that adding an APN subscription has many touch points in the mobile network and it is impractical or unsustainably expensive to do so as people join and leave hundreds or thousands of enterprises. Nodes like HLR/HSS, SGSN/MME, GGSN/P-GW and the like were not designed to be opened to each enterprise so that they can manage enterprise connectivity of their mobile employees. Clearly, there is a need for an enterprise managed element within the mobile network and for a method to steer signaling and traffic in a way that such an enterprise managed element can have control over enterprise access. 
       SUMMARY 
       [0008]    The embodiments disclosed herein provide a solution so that an enterprise can provision BYOD devices of its employees in the mobile packet core and define rules for security, application distribution and steering of signaling and traffic from such BYOD devices. Further, when such employment relationship is terminated the user&#39;s BYOD is able to be restored to its pre-employment functionality. 
         [0009]    An aspect of the embodiments disclosed herein is the trusted Enterprise Broker (EB) which is a function that may reside in the mobile packet core. The EB provides application programming interfaces (APIs) for provisioning of per enterprise policies and for provisioning of supplemental data for each subscriber for that enterprise. It augments private networking capabilities of the mobile packet core with enterprise specific security policies (both static and dynamic) with the possibility of using mobile authentication as a supplement to the enterprise authentication. The EB may include structured information storage. The EB is an intermediary between the mobile device and the traditional HLR/HSS. The EB alters signaling parameters in such a way that traditional nodes HLR/HSS, SGSN/MME, and P-GW/GGSN typically do not need to be changed in order to fulfill interaction and management with the UE. Based on enterprise policies, the EB performs the traffic steering for an associated application to the enterprise network or to external networks. 
         [0010]    Another aspect of the embodiments disclosed herein are methods in a non-roaming scenario that force the flow of signaling for the packet data session to an enterprise capable preferred node (the EB) in the mobile packet core according to the 3GPP rules of the multi-operator core network (MOCN) and Iu-flex/S1-flex based pooling. These methods include the ability to determine if the preferred node is reachable in a non-roaming scenario. This is achieved by setting the Network Resource Indication (NRI) bits of a Packet Temporary Mobile Subscriber Identity (P-TMSI) to a value corresponding to the preferred enterprise node (the EB) in the mobile packet core. 
         [0011]    The third aspect of embodiments disclosed herein are methods in a roaming scenario that force the flow of packet domain signaling to an enterprise capable preferred node (the EB) in the mobile packet core according to the 3GPP rules of Routing Area Update (RAU). This may be achieved by setting the higher bits of MSIN part of the IMSI that are typically used to indicate preferred HLR/HSS in the mobile network to a value corresponding to the preferred enterprise node. These methods include the ability to instruct the traditional SGSN or MME to select the preferred enterprise node as the packet data gateway so that enterprise specific external networking and policies are uniformly available in this scenario. 
         [0012]    The fourth aspect of embodiments of this disclosure are methods in a non-3GPP based access scenario (e.g., Wi-Fi) to force the flow of signaling and traffic to an enterprise capable preferred node (the EB) in the mobile packet core according to the 3GPP rules of Interworking Wireless Local Access Network (IWLAN) interworking. This ensures that enterprise specific external networking and policies are uniformly available in this scenario. 
         [0013]    The embodiments disclosed above include a standard data capable enterprise UE as well as virtualized enterprise containers within the UE. 
         [0014]    The fifth aspect of the embodiments disclosed herein is the interaction of the enterprise UE or enterprise container with the EB in the mobile packet core so that a chain of trust can be established from the user personal identification number (PIN) to user subscriber identity module (SIM) and enterprise credentials. An Enterprise Container (or Enterprise Application Container) (EC) is a virtualized instance of an enterprise qualified mobile device which serves as an “isolated” container for enterprise authorized applications and operates as per enterprise policies that are made available on a per enterprise basis by the EB. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements. 
           [0016]      FIG. 1  is a block diagram illustrating mobile communications over a typical 3GPP packet core network and the interconnection with RANs and external networks (e.g., Internet or enterprise network). 
           [0017]      FIG. 2  is a block diagram illustrating functional entities of UE and associated identities used in such a system. 
           [0018]      FIG. 3 a    is a block diagram illustrating the EC and EB entities in the context of a mobile network according to one embodiment of this disclosure. 
           [0019]      FIG. 3 b    is illustration of the structure of an International Mobile Subscriber Identity (IMSI). 
           [0020]      FIG. 3 c    is illustration of the structure of a Packet Temporary Mobile Subscriber Identity (P-TMSI). 
           [0021]      FIG. 4  is a block diagram illustrating EC and EB entities in the context of a mobile network according to another embodiment. 
           [0022]      FIG. 5  is a block diagram illustrating EC and EB entities in the context of a mobile network according to yet another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    In the following description, numerous details are set forth to provide a more thorough explanation of the embodiments of this disclosure. It will be apparent, however, to one skilled in the art, that the embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the disclosure. 
         [0024]    Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification do not necessarily all refer to the same embodiment. 
         [0025]    According to the embodiment shown in  FIG. 3 , a system EB  300  in a mobile packet core network interacts with enterprise UE  301  or EC  302  located within the UE  301 . While the embodiment is described with a focus on EC  302 , it is equally applicable to UE  301  which may be enterprise issued. EB  300  includes an access network interface unit, a processor and memory (database (DB)  310 ). EB  300  receives provisioning data and policies from Enterprise Private Network  315  that it stores in structured form in database  310  regarding enterprise&#39;s employees subscription and devices. The provisioning data and policies may be continuously updated by the Enterprise Private Network  315  so that the security policies of the network  315  are both static and dynamic. The user plane  312  of EB  300  uses this provisioned information to steer the data from UE  301  to the Internet  314  or Enterprise Private Network  315 . 
         [0026]    One aspect of this disclosure is the steering of signaling from EC  302  to EB  300  through RAN  303  which is coupled to EB  300 . According this embodiment, EB  300  is associated with an identification code that allows RAN  303  to select EB  300  among other nodes as the place to seek services as per the 3GPP rules of MOCN and Iu-flex/S1-flex features. U.S. patent application Ser. No. 12/987,546, filed on Jan. 10, 2011, and which is hereby incorporated by reference in its entirety, describes a standard 3GPP mechanism as well an enhancement and for the purposes of this disclosure both may be used. 
         [0027]      FIG. 3 b    shows the structure of such an identification code-IMSI 3a00 (which is also referenced as  221  in the description with respect to  FIG. 2 ). In the standard MOCN mechanism, the Mobile Network Code (MNC) 3a02 part of IMSI 3a00 is used to select the core network node for service. RAN  303  of  FIG. 3 a    is configured with a map or a table in order to associate an MNC to a core network node and it selects the correct node accordingly. Therefore according to this embodiment, EB  300  is associated with a unique MNC if the standard MOCN mechanism is used. As per the enhancements described in U.S. patent application Ser. No. 12/987,546, the one, two or three highest digits of the Mobile Subscriber Identification Number (MSIN) 3a03 are used to select the core network node (EB  300 ) for service. In  FIG. 3 b    these digits are termed Network Resource Identifying part of MSIN (NRIM) 3a04. RAN  303  of  FIG. 3 a    may be configured with a map or a table in order to associate a NRIM to core network node mapping and it selects the correct node (EB  300 ) accordingly. Therefore according to this embodiment, EB  300  is associated with a unique value for the NRIM 3a04. The IMSI 3a00 is also in a SS7 signaling network to derive a global title that allows routing of a signaling message to the correct node. In the globally connected network, the MCC 3a01 and MNC 3a02 part of the IMSI 3a00 help locate the home operator&#39;s HLR/HSS  313  for roaming users. For many large operators, there could be many HLR/HSS&#39;s. In order to reach a specific HLR/HSS within the operator&#39;s network, the higher digits of the MSIN 3a04 may be use (i.e., the NRIM is used as a common practice). 
         [0028]    IMSI 3a00 is the private identity of a subscriber and in 3GPP networks its use in signaling with the UE  301  is only recommended when the UE does not have a temporary identity such as Temporary Mobile Subscriber Identity (TMSI), P-TMSI, Global Unique Temporary UE Identity (GUTI), etc. While this embodiment as described utilizes a P-TMSI, it should be evident to those skilled in the art that the embodiment can be practiced with other temporary identities as well. 
         [0029]    Upon initial signaling using IMSI, the packet core network  110  assigns a temporary identity P-TMSI to the UE  301 . (P-TMSI is referenced as 3b00 in the description with respect to  FIGS. 3 c    and  223  in the description with respect to  FIG. 2 ). The UE  301  is supposed to use the P-TMSI in all subsequent signaling as long as the core network node (EB  300 ) accepts it. The packet core network  110  may have a policy of refreshing the P-TMSI after a certain duration or upon failure to understand it. While generating the P-TMSI, the core network node (EB  300 ) also embeds its own identity in it in the form of Network Resource Identifier (NRI) 3b01. The structure of P-TMSI 3b00 is shown in  FIG. 3   c.  Bit  29  is designated on the P-TMSI 3b00 as Initial Use Indicator 3b02. As the per the Iu-flex/S1-flex feature of the 3GPP specification, RAN  303  of  FIG. 3 a    looks at the NRI 3b01 and routes the signaling to the corresponding core network node. 
         [0030]    One aspect of this disclosure is the method which allows EC  302  to steer signaling to the preferred core network node EB  300 .  FIG. 2  shows a block diagram of UE  301  having Personal App Container (VM)  225  and EC  302 , a self contained VM, according to this embodiment. UE baseband  210  in UE  301  is the module responsible for radio communication with the mobile network. The Subscriber Identity Module (SIM)  220  (also in UE  301 ) is a physical device with its own processor and storage. The SIM  220  is mainly used for authentication and as the storage for provisioned parameters, network parameters, etc. during the course of UE&#39;s  301  interaction with the network (e.g., IMSI  221  and P-TMSI  223  are stored in the SIM  220  files along with TMSI  222  and P-TMSI Signature  224 ). UE  301  or an authorized application on UE  301  can communicate with SIM  220  and read and modify parameters for these files. As per this disclosure, EC  302  is provided with the NRI 3b01 of EB  300  through pre-programming or by using any data transfer mechanism. When EC  302  on UE  301  is invoked, EC  302  checks the public land mobile network (PLMN) information either by querying the baseband  210  or by reading it from SIM  220 . If UE  301  is in its home PLMN (home operator&#39;s network) it proceeds to read and save P-TMSI  223  and IMSI  221  from the SIM  220 . Then it over-writes the Initial Use Indicator and NRI fields in the P-TMSI  223  with a pre-programmed value for the initial use and for the EB  300  respectively. Any subsequent signaling from UE  301  will now be steered by RAN  303  to EB  300 . 
         [0031]    According to this disclosure, in  FIG. 3   a,  upon receiving a service request with P-TMSI Initial Use Indicator field set to “Initial Use” from EC  302 , EB  300  will ignore the P-TMSI Signature  224  and initiate the procedure to obtain IMSI  221  from UE  301 . Upon receiving IMSI  221 , the EB  300  will be able to locate the associated employee record in database  310 . It will then invoke the AAA  311  function to query the HLR/HSS  313  of the subscriber in order to obtain the mobile subscriber record and authentication vectors (e.g., response, other key materials, etc.). At this point, the EB  300  will perform full authentication with UE  301 . Since UE  301  has the SIM  220  associated with the mobile subscriber, the authentication should go through. At this point EB  300  can assign a new P-TMSI  223  with predetermined rules to route subsequent signaling. The Initial Use Indicator field will be set to “Active”. All other bits except the NRI bits could be set to identify the enterprise and the employee user. EB  300  can now proceed to fulfill the requested service as per the employee record and subscriber record obtained from HLR/HSS. 
         [0032]    As an example, if the requested service from EC  302  was to establish a packet data protocol (PDP) context, the EB  300  will fulfill that and instruct the RAN  303  to send the user traffic to EB  300 . EB  300  in consultation with the enterprise policy will set the traffic path to the enterprise  315  or to the Internet  314 . Since EC  302  contains only enterprise authorized applications, each application can setup its own Internet Protocol (IP) flow toward the servers. Alternatively, all such applications can share a single HyperText Markup Language 5 (HTML5) connection between EC  302  and EB  300  and then EB  300  can proxy each flow to external entities. Once the EC  302  and EB  300  communication path is established, EC  302  can allow the download of enterprise approved applications. Thus without the loss of generality this process provides for comprehensive communication capability for the EC  302 . 
         [0033]    Another aspect of this disclosure is the establishment of a communication between EC  302  and EB  300  when UE  301  is under a RAN that cannot directly reach EB  300 . In such a scenario, as also shown in  FIG. 3   a,  RAN  303  connects to SGSN  308  and EC  302  will need to find a path to the EB  300 . SGSN  308  uses subscriber&#39;s IMSI  221  to reach the associated HLR. When EC  302  accesses RAN  303  with a pre-programmed NRI value in the P-TMSI  223 , RAN  303  will either fail to route the signaling or will route to an SGSN that will not recognize the P-TMSI and/or P-TMSI signature. Upon recognizing failure of the service request based on a modified P-TMSI, EC  302  will modify the MNC 3a02 field or NRIM 3a04 field depending on the home operator policy. Subsequently, when the SGSN requests the IMSI  221  from UE  302 , UE  302  will respond with the modified IMSI. The MNC or NRIM field in the modified IMSI will point SGSN to the EB  300  as the HSS/HLR. When the signaling messages from SGSN reach EB  300 , it will then restore the IMSI based on pre-provisioned information. EB  300  will then query the real HSS/HLR for that subscriber based on the restored IMSI using the built in AAA function  311 . At this point, EB  300  will receive mobile subscription data. Based on employee record and mobile subscriber data received from HLR  313 , EB  300  will insert enterprise APN in the subscriber record and deliver it to the SGSN so that it can respond to the service request. The enterprise APN will resolve to the EB  300  as the GGSN and the user traffic will come to it. From here onwards it works in the same way as described in previous described processes of this disclosure. 
         [0034]    Another aspect of this disclosure is the establishment of communication between EC  302  and EB  300  when UE  301  is roaming in a foreign mobile network (i.e., Visited PLMN (VPLMN))  304  as shown in  FIG. 3 a    when EC  302  is invoked. When EC  302  identifies that is in a foreign VPLMN  304 , according to this disclosure, EC  302  will modify the IMSI just as described previously. The SGSN in the visited network will go through the roaming exchange  305  to reach the EB  300  as the HSS/HLR. The rest of the procedures are the same. 
         [0035]    When EC  302  is shutdown, or when a user switches to another VM on the UE  301 , according to this disclosure EC  302  will restore the original P-TMSI  223  and the IMSI  221  that it had read during the startup time. 
         [0036]    When the employment arrangement with the enterprise ends, the enterprise can instruct the EC  302  to wipe or disable itself. The enterprise may also tell EB  300  to remove service for such employee. Without a functional EC  302 , UE  301  will be in equivalent condition prior to being provisioned in EB  300 . 
         [0037]      FIG. 4  shows another embodiment of this disclosure whereby the EB  416  functionality is realized partially or completely in existing packet core nodes. For example, EB  416  can be implemented fully in SGSN  407  or partly in HLR/HSS  411  and partly in GGSN  408 . Similarly, for 4G based access, EB  416  can be realized in MME  409  and P-GW  414  or in HLR/HSS  411  and P-GW  414 . Finally for Wi-Fi based access, EB  416  can be realized in the ePDG  415 . For access from visited foreign network VPLMN  419 , EB  416  inside the SGSN  407 , MME  409  or HLR/HSS  411  can be reached via roaming exchange  420 . To the skilled in art it should be clear that realization will be able to provide equivalent functionality as in the previous embodiment. 
         [0038]      FIG. 5  shows another embodiment of this disclosure whereby EB  510  functionality is realized as an extension of a collapsed and virtualized packet core  550 . A Virtualized Optimized Core (VOC) is a flexible and scalable realization of essential functions of a mobile packet core in a service oriented (SOA) way. A 3G/4G/Wi-Fi access network can be served by the VOC instead of the traditional mobile packet core. The private networking capabilities of the VOC are described in U.S. patent application Ser. No. 13/763,653, filed Feb. 9, 2013, and titled “Method and System for Automatic Provisioning of Enterprise Private Network Over 3G/4G Mobile Wireless Networks While Maintaining Respectively Consistent Identities”, which is hereby incorporated by reference in its entirety. In  FIG. 5 , VOC  550  interfaces with local RAN  503 , RAN  505 , and Wi-Fi  508 . It also interfaces with Visited Network VPLMN  506  through roaming exchange  507 . To the skilled in art it should be clear that realization will be able to provide equivalent functionality as the previous embodiments. 
         [0039]    Some portions of the preceding detailed descriptions have been presented in terms of processes and symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A process is here, and generally, conceived to be a self-consistent sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
         [0040]    It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the above discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
         [0041]    Embodiments of the present disclosure also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer having a communication (or network) interface, a processor and memory and selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable medium. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium (e.g., read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.)), etc. 
         [0042]    The processes and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method operations. The required structure for a variety of these systems will appear from the description above. In addition, embodiments disclosed herein are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of embodiments as described herein. 
         [0043]    Although process (or method) steps may be described or claimed in a particular sequential order, such processes may be configured to work in different orders. In other words, any sequence or order of steps that may be explicitly described or claimed does not necessarily indicate a requirement that the steps be performed in that order unless specifically indicated. Further, some steps may be performed simultaneously despite being described or implied as occurring non-simultaneously (e.g., because one step is described after the other step) unless specifically indicated. Moreover, the illustration of a process by its depiction in a drawing does not imply that the illustrated process is exclusive of other variations and modifications thereto, does not imply that the illustrated process or any of its steps are necessary to the embodiment(s), and does not imply that the illustrated process is preferred. 
         [0044]    In this disclosure, devices that are described as in “communication” with each other or “coupled” to each other need not be in continuous communication with each other or in direct physical contact, unless expressly specified otherwise. On the contrary, such devices need only transmit to each other as necessary or desirable, and may actually refrain from exchanging data most of the time. For example, a machine in communication with or coupled with another machine via the Internet may not transmit data to the other machine for long period of time (e.g. weeks at a time). In addition, devices that are in communication with or coupled with each other may communicate directly or indirectly through one or more intermediaries. 
         [0045]    In the foregoing specification, embodiments of this disclosure have been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.