DISPLAYING ADDITIONAL INFORMATION ALONG WITH OR INSTEAD OF A NETWORK IDENTIFICATION

Abstract: The application relates to a mobile communication device and mobile communication system, in which it is possible to display additional information along with or instead of a network identification that is associated with a network code received from a network onto which the mobile communication device is logged. This greatly enhances the performance of mobile communication devices, such as mobile telephones, with respect to the possibility of roaming between different independently operated networks, as the range of a given network may be extended virtually.

Description: DISPLAYING ADDITIONAL INFORMATION ALONG WITH OR INSTEAD OF A NETWORK IDENTIFICATION Field of the invention The present invention relates to a mobile communication device that is capable of communicating with different networks, and to a corresponding mobile communication system. An example of such a mobile communication device is a cellular telephone. An example of such a mobile communication system is a cellular communication system consisting of base stations, switching centers and the corresponding control elements. Mobile telephone and communication systems have become an integral part of the modern world. The present invention relates to such mobile communication systems and devices, in which a mobile station is capable of logging onto different networks, i.e. networks established by different network providers and operated independently. A typical example of a standard for mobile communication systems is GSM (Global System for Mobile communication) , which is the dominant mobile communication standard in Europe. In GSM, such independently operated networks are referred to as PLM s (Public Land Mobile Network) . With respect to a given band of frequencies, most European countries have several network providers, and these are usually restricted to one country. In other words, there are typically several independent providers that offer mobile communication services in one geographic location, and when moving to another geographic location, services from different providers become available. The GSM standard is such that a subscriber to one PLMN may in principle also log on to a network established by another provider. In other words, a subscriber can in principle roam between different PLMNs. The roaming capabilities of a given subscriber may be limited due to individual parameter settings for said subscriber, as will be explained in the following. Location management poses a basic problem for any mobile communication system offering this capability. GSM for example solves this problem by on the one hand using so- called subscriber identity modules (SIM) that are inserted into a mobile station and identify the subscriber associated with the module. The SIM stores all the relevant information that a network requires for identifying a subscriber. In Europe this module is typically provided on a card that can be slid into a mobile telephone. In this way, a subscriber can use any mobile station that fulfills the communication requirements (required frequency band, etc.) for the network to which he subscribes, simply by inserting his personal SIM card. The mobile station then has the subscriber identification that is necessary for communicating with a network. In GSM, the procedure for logging on the network basically consists in sending out a location update request from the mobile station, where said location update request contains the identification data associated with the subscriber. On the network side, the subscriber data is kept in the so-called home location register (HLR) . This is basically a data base for the PLMN to which the subscriber subscribes . The network to which someone subscribes is also referred to as the home PLMN. When the subscriber logs on to his network, i.e. lets his mobile station register with the network (typically this is automatically done when the mobile station is turned on) , the mobile station sends out data associated with the user that are read from the SIM to the network base station with which it is communicating, by sending out the above mentioned location update request. The network base station forwards the data to the HLR, where the momentary position (in terms of the base station with which the mobile station is communicating) of the subscriber can then be stored, specific parameters associated with the user (e.g. a predetermined priority for channel allocation) can be sent back to the base station and generally the services provided to the given subscriber can be monitored and recorded, e.g. for billing purposes. It should be noted that in GSM, the information pertaining to a given subscriber is also stored in the so-called mobile services switching center (MSC) , where one MSC handles communication in a given number of cells, and the PLMN comprises several MSCs. In order to allow a subscriber to receive services from other PLMNs than his home PLMN, the PLMNs must communicate between themselves. A PLMN to which a specific subscriber does not subscribe is also referred to (in GSM) as a visited PLMN or VPLMN. A PLMN keeps track of visiting mobile subscribers in the so-called visitor's location register (VLR), which is kept in each MSC. In other words, when a visiting mobile station sends out a location update request ' to a VPLMN, the MSC handling the cell in which the mobile station is located, can check the VLR to see if this visiting subscriber is already registered there, and if not, can determine the home PLMN from the information provided by the mobile station and contact said home PLMN to thereby find out if services (and which services) can be provided to the visiting mobile station. In the other direction of communication, the PLMN always provides every mobile station that is logged on or attempting to log on with a network ID, so that the mobile station knows which PLMN it is communicating with. This information is of great importance, because, as already mentioned, several providers will typically offer services in one location, so that on the one hand a mobile station will need it to identify and establish a connection with its home PLMN when in range thereof, and on the other hand be able to distinguish the various VPLMNs when outside the range of its home PLMN. The network ID can e.g. be displayed to the user of the mobile station. Typically the mode of operation of the mobile station in which the network ID is displayed to the user is the idle mode in which the mobile station is in a state of waiting to receive incoming calls or to establish outgoing calls. Another mode is a manual selection mode, in which all available networks are displayed to the user, so that he may choose the one he desires. More specifically, in GSM, when searching for a PLMN to log on to, a mobile station will scan various GSM frequencies and receives information transmitted on the so-called broadcast control channel (BCCH) . The mobile station thereby obtains the mobile network code (MNC) of every PLMN serving the given location. The MNC is a two- digit numerical code contained in the so-called location area identity (LAI) of the BCCH system information type 3 and 4 message. The MNC is translated into a respective mobile identity string by referring to a look-up table that is stored in the mobile station at production time. In a manual log on mode, the mobile identity strings of all available PLMNs may be displayed to the user of the mobile station, such that he can choose the network he wishes to log on to. After log on, the mobile identity string associated with the MNC of the PLMN to which the user is logged on to (be it home PLMN or VPLMN) , will be displayed during the idle mode. Due to the above described importance of network identification, the fixed association between the mobile network codes and the mobile identity strings, and also due to numbering plan considerations and existing mobility management mechanisms, the MNC is a vital parameter that can not be changed. Object of the invention It is an object of the present invention to improve the performance possibilities of mobile stations and mobile communication systems with respect to the capability of mobile stations to roam between different independently operated networks. Brief description of the invention This object is solved by devices and systems described in the independent claims. Advantageous embodiments are described in the dependent claims . In the prior art, the mode of operation in which a mobile station typically may display a network ID, is the idle mode. In the idle mode, the mobile station is in a state of waiting for incoming and outgoing calls. In this mode, the control element of a prior art mobile station will first determine that the idle mode is to be entered, and then automatically display the network ID associated with the network code of the network that it is monitoring for incoming calls and with which it would request a connection if the user of the mobile station initiated a call. This is shown schematically in Fig. 2, which represents a portion of the control flow in the mobile station, where SI indicates the step that determines that the idle mode should be entered, S2 indicates the entering of the idle mode (i.e. the appropriate setting of parameters etc.) and S3, which directly follows S2, relates to the control of the display, such that the ID of the network onto which the mobile station is logged is automatically displayed. Naturally, during the idle mode the display may also show other information, such as the signal strength, but the characterizing aspect of the prior art device is that in the mode during which a network ID can be displayed, the network ID is necessarily displayed, and this network ID is always displayed exclusively in a specific predetermined part of the display (e.g. the center) . In accordance with the present invention, when a mobile station enters a mode of operation in which a network ID corresponding to a received network code may be displayed (e.g. the idle mode) , the network ID is not automatically displayed, much rather a predetermined condition is first checked, and then the data to be displayed is determined in accordance with the result of said check. The fact that the displayed data is not automatically determined from the received network code enhances the performance of the mobile station, as entirely new features can be implemented with respect to the capability of the mobile station to roam between different independent networks, even though the network codes remain unchanged. According to a preferred embodiment, after having entered the idle mode, the mobile station first checks if a specific type of data is present, and if said specific type of data is present, then it is displayed instead of or in addition to the data corresponding to the network code broadcast by the network onto which the mobile station is logged, which conventionally is displayed automatically and exclusively. An example that relates to the control shown in Fig. 2 is shown in Fig. 1. The same reference numerals indicate the same steps. In contrast to what is shown in Fig. 2, the control in Fig. 1 is conducted such that after entering the idle mode in step S2, it is determined in step S4 if the above mentioned specific type of data (e.g. a predetermined network ID that is always to be displayed for the subscriber of the mobile station, even when he is logged on to a different network) is present or not. If it is present, then control moves to step S5 in which the specific type of data is displayed in place of the network ID. On the other hand, if no such data is present, then control moves to step S3 and the network ID decoded from the network code of the network onto which the mobile station is logged is displayed. The replacing mentioned in connection with step S5 means that the network ID or the specific data are displayed in the same part of the display. As an alternative to step S5, the specific data may also be displayed together with the network ID decoded from the network coded, preferably in close vicinity on the display. This specific type of data, which is intended to replace or complement the data associated with the network code, can be identifiable by a predetermined address in data relating to the subscriber, be it in the data stored on a SIM or the data received from the network after having logged on. The determination of the presence of said predetermined data can be done in any suitable or desired way, e.g. by checking if a specific flag is set, or by going to the predetermined address and checking if bits other than zero are stored there. In other words, the present invention provides the possibility of not displaying or not exclusively displaying the network ID associated with the network onto which a mobile station is logged, even though the mobile station is in a mode of operation in which this network ID would commonly be displayed exclusively. This additional feature offers great advantages. For example, this specific type of data can be the ID of the network to which the subscribers subscribes, i.e. the ID that is conventionally displayed in the idle mode in response to receiving the home network code. Then, even if the subscriber is logged on to another network, e.g. when visiting a foreign country, in which case the conventional device would display the network ID related to the network code of that network, the device according to the invention can display the network ID of the subscriber's home network instead of the network ID belonging to the network onto which the user is logged, which gives the subscriber the impression of still being in his home network. This increases the service identification potential for the provider of the home network, as it provides a virtual extension of the actual network. This advantage is especially pronounced in the context of what is called national roaming, i.e. when two or more network providers who compete in more densely populated areas, cooperate in a thinly populated, rural area to thereby save costs. In these rural areas only one of the providers offers services to the subscribers of both networks, where typically certain areas will be covered by one provider, and other areas by the other. Then, with the above described mechanism of the present invention, the subscriber will always see the ID of the network to which he subscribes displayed in the typical ID display mode (e.g. the idle mode) and thereby always have the impression of being in his home network, although actually he may be roaming in the network of another provider . Naturally, any type of data can be displayed, not only the above described network ID of the home network. Another very advantageous application of the present invention is in the relationship between service providers and network providers . Network providers run the actual networks, whereas service providers offer and sell services for and over networks. Such a service may be the establishing of long distance connections at a less expensive rate, or a call-back service. As an example, in order to access a specific service provider, the subscriber in a given network must dial a specific service number. He is then connected to the desired service, for example a low cost long distance operator. It is clear that most network providers are also service providers, but a number of service providers can exist beside the network provider of a given network. As already indicated above, in conventional systems only the network ID of the network onto which a user is logged, is displayed. In other words, there is no possibility for a service provider to display an ID of his own or similar information. By contrast, with the present invention this is possible, as the service provider can either communicate a message to be displayed in the idle mode (or other appropriate mode) to the mobile device, or this data can be contained on the subscriber identity module if the service provider is also the provider of the subscriber identity module. In this way, the service providers can "brand" their services, i.e. make themselves seen to the user. For example, a service provider who uses one or more established networks and sells subscriptions, can have his own ID displayed on the mobile devices of his subscribers, so that these subscribers have the impression of being in a network provided by the service provider. As in the previous case this is naturally well applicable in the case that the service providers offers services over more than one network, so that the subscriber will have the impression of being in a given network (which in reality does not exist at all) even though he is in fact roaming between different networks. In other words, it is possible to create a virtual network for service providers. Brief description of figures Fig. 1 shows a portion of a flow chart for controlling the operation of a mobile communication device, said portion indicating the control of the display in accordance with an embodiment of the present invention. Fig. 2 shows a portion of a flow chart for controlling the operation of a mobile communication device, said portion indicating the control of the display in accordance with the prior art. Fig. 3 shows a typical example of a mobile communication device. Fig. 4 is a block diagram that schematically shows the structure of a mobile communication device. Fig. 5 shows a schematic explanation of how additional display information is provided to a mobile station in accordance with an embodiment of the invention. Fig. 6 shows an example of the structure of a message provided to the mobile station shown in Fig. 5. Fig. 7 shows an example of the structure of the supplementary display information in accordance with the invention. Fig. 8 shows a schematic explanation of how additional display information is provided to a mobile station in accordance with another embodiment of the invention. Fig. 9 shows a portion of a flow chart for controlling the operation of a mobile communication device, said portion indicating the control of the display in accordance with another embodiment of the present invention. Detailed description of the present invention The following detailed description will generally be given in the context of GSM. This serves the purpose of better understanding and is to be seen as a preferred application of the present invention. However, the present invention is by no means restricted to systems working in accordance with GSM. Much rather, the present invention can be applied in all devices and systems having the features described in the appended claims. Figure 3 shows a representation of a mobile telephone as an example of a mobile communication device. The telephone 1 has an antenna 2 for transmitting and receiving wireless communications. Furthermore, a display 3 is provided, on which specific information for the user of the mobile telephone can be displayed. In the example of Fig. 3, the information regarding the network provider is a network identification 31, in this example called "Teleplus". Moreover, other information 32 is shown, e.g. the signal strength etc. Furthermore, the mobile telephone 1 comprises number keys 4 for entering numbers, e.g. telephone numbers, variable keys 7, which may fulfill any desirable function, and a loudspeaker 5 for letting a user hear incoming voice information, and a microphone 6 into which the user speaks when communicating. Fig. 4 schematically shows the structure of the mobile communication device shown in Fig. 3. Identical elements have the same reference numeral . The communication device is controlled by a central control unit 10. This central control unit may e.g. comprise a microprocessor and suitable storage elements, such as RAMs and ROMs containing the programs and data necessary for the functioning of the microprocessor. This control unit 10 is connected with the various parts of the mobile communication device, to thereby control the data flow between these various parts and control their individual operation to thereby determine the overall operation of the mobile communication device. As shown in Fig. 4, the antenna 2 is connected to a transceiver 11, which transmits and receives signals on a appropriate frequencies under the control of control unit 10. The data to be sent and data received by the transceiver 11 is manipulated in a data processor 12, which e.g. appropriately digitizes analogue voice information coming from the microphone β, and also converts digitized information into analogue information to be output by speaker 5. Moreover, specific control information received through antenna 2 and transceiver 11 is passed to the control unit 10, and vice versa control information from control unit 10 is also processed by data processor 12, in order to be sent out from the mobile communication device. The control unit 10 is also connected to the keyboard 4 and the display 3, to thereby register the pushing of the keys, and to control which data is displayed on the display 3. The mobile communication device or mobile station also comprises a SIM connector 13, i.e. a means for receiving a subscriber identity module. Fig. 4 also shows such a subscriber identity module (SIM) 14, although this is in principle not a part of the communication device per se. Much rather, the SIM 14 is inserted into the communication device prior to operation, such that all of the subscriber-related data on the SIM 14 can be accessed by the control unit 10 through the SIM connector 13. As explained previously, in European GSM systems the SIM is generally provided on a card that is inserted into the mobile telephone prior to use, where a chip having standardized contacts is provided on the card, such that appropriate counter contacts inside the mobile telephone constitute the SIM connector 13 shown in Fig. 4. This technology is well-known and therefore will not be explained further. Naturally, the module can be provided in any other suitable way, e.g. as a circuit chip package that can be attached to a designated part of a printed circuit board in the mobile communication device. In accordance with the present embodiment, the control unit 10 controls the operation of the mobile communication device 1 in accordance with the steps shown in Fig. 1. Step SI represents an arbitrary step in the control flow conducted by the control unit 10 that leads to the idle mode being entered (step S2) . The idle mode is defined as that mode in which the mobile communication device is in a state of waiting for incoming calls or outgoing calls or any user actions, i.e. the mobile station waits to see if the base station associated with the cell in which the mobile station is located sends a message indicating that a call is being directed towards the mobile station, or waits for the user of the mobile station to place a call or perform some other action. Conventionally, mobile stations display the network identification information associated with the mobile network code received from the network onto which the mobile station is logged. In other words, the conventional mobile station automatically decodes the received mobile network code on the basis of the predefined tables stored in the mobile station at production time, and displays the corresponding information. In other words, if the subscriber to a network having the identification "Teleplus" (i.e. "Teleplus" is the name of his home PLMN) is logged on to another network having the network identification "Money- sy-phone" ( "Money-sy-phone" is the visited PLMN), then "Money-sy-phone" will automatically be displayed in the display 3 (see Fig. 3) , instead of the shown network identification "Teleplus" (31 in Fig. 3) . In contrast thereto, in the present embodiment, step S4 determines if a specific type of date is present. In this embodiment, this means that the control unit 10 checks to see if there is data at a predetermined address on the subscriber identity module 14, said specific data being an alternative network identification, and if said specific type of data is present, then step S5 specifies that this specific type of data be displayed. As an example, at a predetermined address of the subscriber identity module, the network identification corresponding to the subscriber's home PLMN (i.e. "Teleplus") could be stored, and then the mobile station would display "Teleplus" on the display 3, as shown in Fig. 3, although it is in fact logged on to the network referred to as "Money-sy-phone" . In this way, the subscribers to "Teleplus" have the impression of an extended network, i.e. the network is virtually extended. This example is equally well applicable to the case that "Teleplus" is the name of a service provider using the network named "Money-sy-phone" . Then, despite a mobile device being logged onto the "Money-sy-phone" network, "Teleplus" can be displayed, such that the user considers himself as using the (virtual) "Teleplus" network. On the other hand, should no such specific type of data be present at the predetermined address (e.g. because the provider of the home PLMN does not wish to use the possibilities of the present invention) , then the processing continues to step S3, in which the network ID associated with the received mobile network code is displayed, as in the prior art. In other words, in the above example, the network identification "Money-sy- phone" would be displayed. In this way, the system remains compatible with the conventional implementation, because if the mentioned specific type of data is not present, then the mobile station will default into the conventional behavior. In summary, a check is performed with regard to the information to be displayed in the ID display mode, and the data that is displayed at the end, is determined on the basis of said check. An example of the structure of the stored additional display information is shown in Fig. 7 and will be explained in more detail further on. The above mentioned embodiment can be modified in a number of ways. For one thing, the precise implementation of step S4 can be in any suitable or desired way, i.e. it is possible that this step is not conducted by looking for the presence of the alternative network identification, but much rather only looking if a specific flag is set at a predetermined location in the data on the subscriber identity module. For example, if such a flag is set to a value of 1, then this means that the specific type of data is present, and consequently such data is read out from a predetermined address and then step S5 follows, whereas if the flag is set to 0, then step S3 is automatically conducted. Also, step S5 may be embodied in several different ways. For example, instead of only displaying the alternative information stored on the subscriber identity module, it is equally well possible to display both the network identification associated with the mobile network code received from the network to which the mobile station is logged and the additional information on the subscriber identity module at the same time. In other words, in the context of the above mentioned example, this means that both "Teleplus" and "Money-sy-phone" would be displayed at the same time. Another alternative to step S5 is the displaying of the additional information from the subscriber identity module for a given period of time and then displaying the network identification associated with the mobile network code in a subsequent period of time, and then repeating this process as long a the mobile station is in the idle mode. In other words, in the context of the above example, this means that "Teleplus" and "Money-sy-phone" would be displayed in alternation. The last two embodiments, in which both the additional information from the subscriber identity module and the network identification corresponding to the received mobile network code are displayed, are advantageous in that the user of the mobile station is informed of the network onto which he is logged, but at the same time is also reminded of his home network. In connection with the above embodiments, the supplementary information on the subscriber identity module was an additional network identification to be displayed in place of or together with the network identification belonging to the network onto which the mobile station is actually logged. Naturally, the present invention is by no means restricted thereto. Much rather, the type of information displayed in step S5 (be it exclusively or mutually with the network identification of the network to which the mobile station is logged) can basically be of arbitrary nature. For example, it can be an indication of a specific type of service provided to the given subscriber (e.g. "Gold Member", "VIP Service" etc.). In such a case, the alternative display mode can advantageously be to display the service indication together with the network identification of the VPLMN. In this way the subscriber can see that his special service is being provided, even though he is roaming. Also, it would be possible to provide the network identification of the home PLMN together with the service indication (i.e. "Teleplus Gold Member" etc.). In this case the alternative display mode could again be to show this information in place of the network identification of the VPLMN, to thereby give the subscriber the impression of an extended network. As can also be seen from this example, the present invention does not only enhance the performance possibilities with respect to the roaming capability of a mobile communication device, it also provides new possibilities in a single network. Using the above mechanism, a network provider can let an indication of a specific type of service be displayed to those subscribers entitled to that service, where the alternative display mode would here advantageously consist in displaying the service indication together with the network identification. Those subscribers not entitled to the service will simply see the network ID, as usual . Figure 9 shows another embodiment of the present invention, where identical or equivalent steps carry the same reference signs as in Fig. 1. The procedure is the same as in the previous embodiments, except that an additional step S6 is provided, in which it is determined if the visiting network allows the display of the additional data. If not, then the control procedure goes to step S3, i.e. the network identification of the VPLMN is displayed, as in a conventional system. This step S6 can be implemented in any suitable or desired way, for example by having the mobile communication device send a corresponding request message to the VPLMN and then conducting step S6 in accordance with the answer message, or the necessary information can already be provided by the VPLMN in the answer to the location update request sent by the mobile communication device before logging on. This embodiment further increases the performance possibilities, as the control over what is displayed to the user of a mobile communication device is not only in the hands of the home PLMN of that user, but also in the hands of individual VPLMN providers. A variation of this embodiment consists in the provider of the VPLMN not only influencing if additional and/or alternative information is to be displayed, but also which information and how it is to be displayed, e.g. in alternation or simultaneously. This may e.g. consist in the VPLMN checking the type of phone sending a location update request in response to said location update request, and then sending data on how a display is to be conducted in dependence on the capabilities of the phone. As can again be seen, the present invention increases the performance possibilities of a mobile communication device and system tremendously. It should also be noted that the processing shown as steps S4 and S5 in Fig. 1 and steps S4, S5 and S6 in Fig. 9 is only an example of the present invention, as the invention generally consists in checking for a predetermined condition in the ID display mode (e.g. the idle mode) and then determining the data to be displayed in said mode in accordance with the result. For example, this processing can also be more complicated and it is possible that there are more than two possibilities for the data to be displayed. As indicated in connection with the embodiment shown in Fig. 9, some of the processing (decisions) can be made at one or both of the mobile services switching centers (MSC) of the VPLMN and HPLMN. In the above embodiments, this additional information for being displayed in step S5 is always stored in the subscriber identity module, which needs to be inserted into the mobile station before being able to use it. However, the present invention is by no means restricted thereto. Much rather, it is equally well possible that this additional information to be displayed is transmitted to the mobile station. A system embodying this principle is shown in Fig. 5. The embodiment of Fig. 5 is based upon GSM, but requires a change of standardization with respect to present implementations, as will be explained. The additional information to be displayed is obtained in the following way. Initially, the mobile station selects a network and attempts to log onto the network by sending a so-called location update request. This is still in accordance with the known method of operation. Such a location update request, which essentially constitutes a request for registering with a given network is passed on to the home location register HLR of the subscriber using the mobile station. This is also still in accordance with known systems . According to the invention, the additional information to be displayed is stored as an alphanumeric string of limited length in the subscriber record in the home location register HLR. If the home location register, which belongs to the home PLMN of the subscriber accepts the location update, a message of acceptance will be returned to the mobile services switching center MSC at the visiting PLMN onto which the subscriber is trying to log. In accordance with the invention, the additional information to be displayed is retrieved from the subscriber record and is sent along with the message of acceptance. In Fig. 5 this message is referred to as MAP- Update-Location-Result (MAP = Mobile Application Part) . The visitor's location register at the mobile services switching center receives this message and passes the information along in a DTAP-Location-Update-Accept- Message to the mobile station (DTAP = Direct Transfer Application Part) . The mobile station decodes the message and obtains the additional information to be displayed. The other processing is as explained in the previous embodiment, i.e. if it is determined that additional information is present, then this information is displayed exclusively or together with the network ID of the visiting PLMN (as in step S5) , and if this additional information to be displayed is not present in the message from the visitor's location register, then the network ID of the visiting PLMN is displayed, as explained in connection with step S3 of Fig. 1. A variation of the above embodiment can consist in not storing the additional information to be displayed in the home location register HLR at the home PLMN of the subscriber, but to keep such additional information to be displayed, which is associated with a given subscriber, in a table stored in the mobile services switching center's visitors location register (MSC/VLR) , by using the subscriber's IMSI (IMSI = International Mobile Subscriber Identity) as an input. In other words, the additional display information for a given subscriber is stored using that subscriber's IMSI as an identifier. Such a table at the MSC/VLR would have to be updated regularly from a network operation and maintenance center. The advantage of this variation would be that the HLR would remain unchanged, and only that part of the GSM standard relating to the communication between the MSC/VLR and the mobile station (MS), i.e. DTAP, would have to be modified. Fig. 6 shows an example of a DTAP-Location-Update-Accept- Message. As can be seen, the message contains known parameters, and in accordance with the invention, a new additional display information parameter is added at the end, as indicated by the dashed line. Fig. 7 shows an example of the coding of this additional display information parameter. The first octet contains an information element identity (i.e. a tag) for the additional display information, and is followed by an octet describing the display method to be used on the mobile station. This display method can consist of permanent display, temporary display, display together with the existing network identification, or the alternate display with the existing network identification. In other words, the way of displaying the additional display information can be communicated together with the display information. The third octet may contain information specifying the character coding to be used. The intention of this is to use the available character coding schemes already supported by the mobile station. In the example of Fig. 7, octets 4 to m contain n characters that represent the additional display information. In terms of the example cited with the first embodiments of the invention, the string ("Money-sy- phone") would be contained in these characters 4-n, i.e. character 1 would be M, character 2 would be o, character 3 would be n, etc. As already mentioned previously the format shown in Fig. 7 can also be used in connection with the other embodiments of the invention. In other words, in those embodiments, in which the additional display information is stored on the subscriber identity module, then a sequence of octets as shown in Fig. 7 may be stored at a predetermined address on said module. With regard to this format, it may be remarked that by storing the n characters, any arbitrary string can be used as additional display information. If the additional information is itself a network identification (e.g. the network identification of the subscriber's home PLMN, "Teleplus" in the above examples) then it is sufficient to transmit the mobile network code belonging to the network code that is supposed to be displayed as an additional information in place of the octets 4 to m shown in Fig. 7. This alternative simplifies the system, as a transmission or storage of a string of characters that is already stored in the table contained in the mobile station is avoided. A further embodiment of the present invention, in which the additional display information is transmitted to the mobile station, will be explained in connection with Fig. 8. Fig. 8 is similar to Fig. 5 in that first the mobile station sends a location update request to a given network, where the mobile services switching center of the visited network passes said location update request on to the home location register of the subscriber making the request. However, in contrast to the embodiment described in connection with Fig. 5, the present embodiment sends the additional display information in a USSD message (USSD = Unstructured Supplementary Service Data) . The additional display information is stored in the home location register and at a location update the USSD application obtains this additional display information from the subscriber data and transmits it to the mobile station encapsulated in a USSD message. The decisive aspect of USSD is that it is not a part of the standard, much rather the concept of USSD allows for applications that are specific to individual PLMNs. This is due to the fact that USSD messages are handled transparently by intermediate elements. In other words, the MSC/VLR at the visiting PLMN shown in Fig. 8 transparently handles the USSD message encapsulating the additional display information and therefore simply passes the USSD message on to the mobile station. The mobile station can then decode the information. With respect to the embodiment described in connection with Fig. 5, the use of USSD has the advantage that the mobile services switching center and all other intermediate elements between the home location register and the mobile station would not have to be changed, as they would simply transparently pass on the USSD message. According to a preferable variation of the above described embodiment, the USSD message is repeated after a certain time, i.e. the home location register periodically sends a USSD message to the mobile station. Although the advantage of using USSD lies in the fact that the elements between the home location register and the mobile station do not need to be changed, it is nonetheless possible to also implement the invention in such a way that the additional display information is not stored at the home location register, but much rather is stored in the mobile services switching center's visitors location register, where the association between a given subscriber and the additional display information for said subscriber is provided by the IMSI . This is similar to what has already been described in connection with Fig. 5. In this case, a USSD message is only sent from the MSC/VLR to the mobile station. According to a preferred modification of the above embodiment, the information to be displayed (or parts thereof) in the ID display mode (e.g. the idle mode) is generated dynamically, e.g. depending on one or several of the visited network, the possible services for the given subscriber, the type of mobile device being used etc. In other words, the message to be displayed instead of or together with the network ID of the network to which the specific user is logged, is not fixed, but is determined dynamically from case to case and from time to time on the basis of one or more conditions. As an example, in a system in which a specific subscriber in his home network is accorded a high access priority, this can be indicated to the subscriber by an appropriate message displayed together with the network ID, e.g. "HP" in addition to "Teleplus" if the user subscribes to the above mentioned "Teleplus" network. If the user roams into another network that due to an arrangement with that users HPLMN will also accord the high priority access, then the HPLMN can determine this and select "HP" as the additional display information for the ID display mode in that network. On the other hand, if the visited network does not accord any higher priority, then the HPLMN can select an appropriate different display information, such as e.g. "No Pri" to thereby inform the user. This dynamic message determination can also be employed in connection with the embodiments described in connection with Figures 5 to 7. Although the present invention has been described by referring to specific examples, it should be understood that the scope of protection is not restricted to these specific examples, as a person skilled in the art will readily envision various modifications. Much rather, the scope of the invention is defined by the appended claims. Reference numerals are included in the claims for the purpose of better understandability, and do not restrict the scope.

Claims: Claims A mobile communication device (1) that is capable of communicating with a plurality of distinguishable networks, said networks being distinguishable by a unique code that identifies each network, said code being sent out by each network such that it may be received by mobile stations that are in range, where said mobile communication device (1) comprises: a display means (3) for displaying information to the user of said mobile communication device (1) , and a control means (10) for controlling the operation of said mobile communication device (1) , said control means (10) being capable of setting said mobile communication device (1) in a specific state of operation in which said mobile communication device (1) is capable of displaying on said display means (3) data (31) associated with the code of a network from which said mobile communication device (1) has received said code, wherein said control means (10) , after having controlled said mobile communication device (1) to enter said specific state of operation, checks a predetermined condition (S4) and determines the data to be displayed in said state of operation on the basis of the outcome of said check. 2. A mobile communication device according to claim 1, characterized in that said specific state of operation is a state in which said mobile communication device (1) waits for one of incoming calls, outgoing calls and any user action. 3. A mobile communication device according to claim 1 or 2, characterized in that said predetermined condition is the presence of a predetermined type of data. 4. A mobile communication device according to claim 3, characterized in that said predetermined data is display information to be displayed on said display means . 5. A mobile communication device according to claim 3, characterized in that said predetermined data is a flag indicating the existence of display information to be displayed on said display means. 6. A mobile communication device according to claim 4 or 5, characterized in that said display information is associated with the subscriber using said mobile communication device. 7. A mobile communication device according to claim 4 or 5, characterized in that said display information is stored at a predetermined location among data sent to said mobile communication device by the network with which it is communicating. 8. A mobile communication device according to claim 4 or 5, characterized by having a receiving means (13) for a module (14) that carries data identifying the subscriber using said mobile communication device (1) , where said display information is stored at a predetermined location among the data on said module . 9. A mobile communication device according to one of claims 4 to 8, characterized in that said display information is one of network identification data associated with the network to which said subscriber subscribes and service identification data associated with a service provider. 10. A mobile communication device according to one of claims 4 to 9, characterized in that if said predetermined type of data is present, then said display information is displayed by said display means, and otherwise the network identification data associated with the network code received from the network onto which said mobile communication device is logged, is displayed. 11. A mobile communication device according to one of claims 4 to 9, characterized in that if said predetermined type of data is present, then said display information is displayed by said display means together with the network identification data associated with the network code received from the network onto which said mobile communication device is logged, and otherwise the network identification data associated with the network code received from the network onto which said mobile communication device is logged, is displayed alone. 12. A mobile communication system comprising a plurality of distinguishable networks for mobile communication devices, said networks being distinguishable by a unique code that identifies each network and said code being sent out by each network such that it may be received by mobile stations that are in range, where each network may have subscribers that can log onto other networks, and respective display information is stored in conjunction with data relating to each of said subscribers who can log onto other networks, wherein said display information associated with a given subscriber is to be displayed on a mobile communication device used by said given subscriber one of together with a network identification that corresponds to the code received from the network onto which said mobile communication device used by said given user is logged, and instead of a network identification that corresponds to the code received from the network onto which said mobile communication device used by said given user is logged. 13. A mobile communication system according to claim 12, characterized in that said display information for a given subscriber is stored together with other information relating to said given subscriber in a central data base for the network to which said given subscriber subscribes . 14. A mobile communication system according to claim 12, characterized in that said display information for a given subscriber is stored together with other information relating to said given subscriber in a subscriber identity module that identifies said given user and is designed to be connected to a mobile communication device to thereby provide said mobile communication device with the information stored on said module. 15. The mobile communication system according to claim 12, characterized in that said system operates in accordance with GSM and said display information is sent to said mobile communication device (1) in one of - a message formed according to a predetermined data format specified for said display information, and an unstructured supplementary service data message. 16. The mobile communication system according to claim 15, characterized in that said display information is stored in one of - the home location register of the home public land mobile network to which the user of said mobile communication device (1) subscribes, and - the visitor's location register of the visited public land mobile network onto which said mobile communication device (1) is logged. 17. The mobile communication system according to claim 15, characterized in that said display information is determined dynamically by the mobile services switching center handling communication with said mobile communication device (1) . 18. The mobile communication system according to claim 15, characterized in that said display information is determined dynamically in the home public land mobile network to which the user of said mobile communication device (1) subscribes. 19. A subscriber identity module (14) that stores information associated with a predetermined subscriber of a mobile communication network, said module (14) being designed to be connected to a mobile communication device (1) to thereby provide said mobile communication device (1) with the information stored on said module (14) , wherein said module (14) also stores display information to be displayed on a mobile communication device (1) used by said predetermined subscriber, together with or instead of a network identification that corresponds to a unique network identification code received from the network onto which said mobile communication device (1) used by said predetermined user is logged. 20. A method for controlling a mobile communication device (1) that is capable of communicating with a plurality of distinguishable networks, said networks being distinguishable by a unique code that identifies each network, said code being sent out by each network such that it may be received by mobile stations that are in range, comprising setting (S2) said mobile communication device (1) in a specific state of operation in which said mobile communication device (1) is capable of displaying on a display means (3) data (31) associated with the code of a network from which said mobile communication device (1) has received said code, wherein after said mobile communication device (1) has been controlled to enter said specific state of operation, a predetermined condition is checked (S4) and the data to be displayed in said state of operation is determined on the basis of the outcome of said check. 21. The method according to claim 20, characterized in that said predetermined condition is the presence of a predetermined type of data and if said predetermined type of data is present, then predetermined display information is displayed (S5) by said display means, and otherwise the network identification data associated with the network code received from the network onto which said mobile communication device is logged, is displayed (S3) . 22. The method according to claim 20, characterized in that said predetermined condition is the presence of a predetermined type of data and if said predetermined type of data is present, then a further check is performed (S6) if the display of predetermined display information is allowed, and if said further check allows the display, then said display information is displayed (S5) by said display means, and otherwise the network identification data associated with the network code received from the network onto which said mobile communication device is logged, is displayed (S3) . 23. The method according to claim 21 or 22, characterized in that said predetermined type of data is a flag. 24. The method according to claim 21 or 22, characterized in that said predetermined type of data is said predetermined display information. 25. The method according to claim 20, characterized in that if said predetermined condition is met, then one of - predetermined display information alone, - predetermined display information simultaneously together with network identification data associated with the network code received from the network onto which said mobile communication device is logged, and - predetermined display information in alternation with network identification data associated with the network code received from the network onto which said mobile communication device is logged is displayed (S5) by said display means, and otherwise said network identification data associated with the network code received from the network onto which said mobile communication device is logged, is displayed (S3) alone. 26. The method according to claim 25, characterized in that said predetermined condition is the presence of a predetermined type of data and said predetermined condition is met if said predetermined type of data is present. 27. The method according to claim 25, characterized in that said predetermined display information is stored on a subscriber identity module connected to said mobile communication device (1) . 28. The method according to claim 25, characterized in that said mobile communication device (1) and said networks operate in accordance with GSM and said predetermined display information is sent to said mobile communication device (1) in one of - a message formed according to a predetermined data format specified for said display information, and an unstructured supplementary service data message. 29. The method according to claim 28, characterized in that said predetermined display information is stored in one of - the home location register of the home public land mobile network to which the user of said mobile communication device (1) subscribes, and - the visitor's location register of the visited public land mobile network onto which said mobile communication device (1) is logged. 30. The method according to claim 28, characterized in that said predetermined display information is determined dynamically by the mobile services switching center handling communication with said mobile communication device (1) . 31. The method according to claim 28, characterized in that said predetermined display information is determined dynamically in the home public land mobile network to which the user of said mobile communication device (1) subscribes.

Inventors: BOYLAN CORNELIUS, BOYLAN, CORNELIUS
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1999
Main classification: H04Q7
IPC codes: H04W8