WO2011050835A1

WO2011050835A1 - Use of mobile telecommunications network selection data when roaming

Info

Publication number: WO2011050835A1
Application number: PCT/EP2009/064167
Authority: WO
Inventors: Jari Pekka Mustajarvi
Original assignee: Nokia Siemens Networks Oy
Priority date: 2009-10-28
Filing date: 2009-10-28
Publication date: 2011-05-05

Abstract

An access network discovery and selection function or ANDSF management object is described. The ANDSF 5 management object includes network selection data and also includes an override flag. In the event that active ANDSF policies are provided by a home network and a visited network, the override flag is used to determine the extent to which the ANDSF data provided by the home network can be 10 overridden by a visited network.

Description

Title

OF MOBILE TELECOMMUNICATIONS NETWORK SELECTION DATA WHEN ROAMING

The invention relates to network selection mechanisms, such as Automatic Network Discovery and Selection Function (ANDSF) mechanisms .

Many mobile communication devices are able to make use of more than one communication access technology. For example, some mobile communication devices are able to make use of both the 3GPP standard and WLAN (wireless local area

network) .

Providing a mobile communication device with alternative communication technologies has a number of potential

advantages. For example, the mobile communication device may be able to function in areas where only one of a number of access technologies is available. Also, if a user requires a low cost connection, then the cheapest of a number of

available connection options can be chosen. Alternatively, if a user wants to send a large amount of data over a

connection, then a connection with a high available bandwidth can be chosen.

It is known to provide mobile communication devices with information regarding access technologies that are available. Access Network Discovery and Selection Function (ANDSF) mechanisms allow a mobile operator to provide subscriber devices with inter-system mobility policies for automatic, intelligent network selection in a heterogeneous network environment, where a plurality of different non-3GPP access technologies are available together with 3GPP or fulfilling gaps where 3GPP is not available.

Figure 1 is a block diagram of a system, indicated generally by the reference numeral 1, comprising a mobile communication device 2, an ANDSF server 4, a first mobile network 6 and a second mobile network 8.

In the use of the system 1, the ANDSF server 4 provides information to the mobile communication device 2 regarding the priority in which the access networks available to the mobile device (such as the networks 6 and 8) should be accessed. The mobile communication device requests this priority information from the ANDSF server 4, and the ANDSF server returns the requested data to the mobile communication device. The mobile communication device 2 may choose the network to be used with ANDSF communication according to existing network selection information or by any other means available to the mobile device.

Figure 2 is a flow chart showing an algorithm, indicated generally by the reference numeral 10, showing an exemplary use of the system 1 by the mobile communication device 2.

The algorithm 10 starts at step 12, where ANDSF information is obtained. The ANDSF information may, for example, be provided (by the ANDSF server 4) on request from the mobile communication device 2 (in a "pull" mode) or may be provided in a manner determined and initiated by the ANDSF server (in a "push" mode) .

The ANDSF server 4 provides a number of policies for

connecting the mobile communication device 2 to networks (such as the first mobile network 6 or the second mobile network 8) . Priorities are assigned to the various policies and, at step 14 of the algorithm 10, the highest priority valid policy is applied by the mobile communication device 2. A policy is considered to be "valid" if it meets a number of validity conditions. Such conditions may, for example, relate to location or the time of day. The highest priority valid policy is often referred to herein as an "active policy" . The policy selected at step 14 will have a number of access network options associated with it. The access network options will be prioritized within the policy. At step 16 of the algorithm 10, the highest priority access network option of the selected policy is selected at the mobile

communication device 2.

The algorithm 10 moves to step 18 where it is determined whether or not the highest priority access network option of the selected policy has resulted in a successful connection to an available network. If a network connection has been made, then the algorithm 10 terminates at step 24. If a connection has not been made then the algorithm 10 moves to step 20, where it is determined whether or not the selected policy has any more (lower priority) access network options available.

It should be noted that ANDSF information does not define when a network connection is considered to be good enough. Even if a mobile communication device is able to connect to a network, the network quality may still be low. It is left to the mobile communication device to decide whether a given network fulfills its own requirements for the connection. If the network quality is too low, then the mobile communication device can choose the next preferred network in the policy. If no further access network options exist, the algorithm 10 terminates at step 24. If further access network options do exist, then the next highest priority access network is selected at step 22. The algorithm 10 then returns to step 18, where it is determined whether or not the newly selected access network results in a successful connection to an available network. If a connection is made, then the

algorithm 10 terminates at step 24. If a connection is not made, then the algorithm 10 moves to step 20, as discussed above .

The algorithm 10 continues until either a successful

connection is made or all access network options of the selected policy have been tried. In some implementations of ANDSF systems, if the highest priority valid policy does not result in a connection being made, then no further efforts are made to make a connection. In other implementations, if the highest priority valid policy does not result in a connection being made, then the next highest priority policy (if any) is used and steps 16 to 24 of the algorithm 10 are repeated using that policy.

In addition to providing network selection policies, ANDSF allows mobile operators to provide access network discovery information (ANDI) to assist user equipment (UE) in detecting access networks specified in the ANDSF policy rules. Policies are used to list preferred access networks in any given location or time.

Discovery information consists of radio technology specific information like frequencies and channels. This is

particularly important, for example, for WiMAX where blind scanning of the whole frequency domain can take a considerable period of time (perhaps as much as 15 minutes or more) and can use considerable battery resources.

Both policies and discovery information can have validity area, expressed for example using 3GPP Cell Identifier or tracking area data. Typically, an ANDSF server runs in an operator network and delivers the policies and discovery information to a user device either on request from the user device (pull mode) or at the operator's preference (push mode) .

When the ANDSF mechanism was first proposed, it was only intended to provide data that is valid within the area of a single public land mobile network (PLMN) . This network (the "home" network) of the user device was the only network for which ANDSF data was provided. More recently, it has been proposed to provide roaming support using ANDSF data. This means that when a particular user device moves from a home network to a visited network, the user device can still make use of ANDSF information. In one arrangement, when roaming, a user device is able to contact a home operator ANDSF (H- ANDSF) , a visited operator ANDSF (V-ANDSF) or both.

Figure 3 is a block diagram of a system, indicated generally by the reference numeral 30, comprising a mobile

communication device 32, a visited operator ANDSF (V-ANDSF) server 34, a home operator ANDSF (H-ANDSF) server 35 and a network 36 (such as a 3GPP IP access network or some other non-3GPP IP access network) . As shown in Figure 3, the mobile communication device 32 and the V-ANDSF server 34 are located within a VPLMN and the H-ANDSF server 35 is located within a HPLMN. The HPLMN and VPLMN are separated in Figure 3 by a dotted line 38. Accordingly, in the system 30, the mobile communication device 32 is roaming in the network VPLMN and using the network 36 of the VPLM to do so.

When the mobile communication device 32 is in its home network (i.e. served by the HPLMN) , then the device 32 should only use ANDSF information provided by the H-ANDSF server 35. When the device 32 is roaming, as in the system 30, the device 32 should use either ANDSF information provided by the relevant V-ANDSF server (i.e. the server 34) or the H-ANDSF server 35. However, in the event that policies provided by the H-ANDSF server 35 and the relevant V-ANDSF server 34 conflict, it is not currently clear how this should be handled .

The present invention seeks to address at least some of the problems outlined above.

The present invention provides a method of using mobile telecommunications network selection data stored at a user device when the user device is within a visited network, the method comprising: determining whether mobile

telecommunications network selection data (such as automatic network discovery and selection function data) has been provided by a home network of the user device (e.g. whether an active H-ANDSF policy exists) ; determining whether mobile telecommunications network selection data (such as automatic network discovery and selection function data) has been provided by a visited network of the user device (e.g.

whether an active V-ANDSF policy exists) ; and in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, determining the mobile telecommunications network selection data that should be used on the basis of a value of an override element of the network selection data (often _η

the relevant override element is included in the network selection data provided by the home network) . The method is typically carried out at the user device. The provision of an override element provides a degree of control over the network selection data that is used. This control is typically given to the home network (e.g. to an H- ANDSF server) , although this is not essential to all forms of the invention.

The said override element may indicate whether or not the mobile telecommunications network selection data of the visited network should override the mobile telecommunications network selection data of said home network.

The said override element may include at least two states. For example, in one form of the invention, the override element includes a first state, in which the mobile

telecommunications network selection data provided by the home network is used and a second state, in which the mobile telecommunications network selection data provided by the visited network is used. The provision of two states enables a very simple allowed/denied setting to be provided. The said override element may include at least three states. For example, in addition to the first and second states described above, a third state may be provided in which the mobile telecommunications network selection data provided by the home network is selected and, if the mobile

telecommunications network selection data provided by the home network does not result in a suitable access network being provided to the user device, the mobile

telecommunications network selection data provided by the visited network is used. The use of a third state enables more sophisticated co-operation between home networks and trusted networks that a simple allowed/denied setting.

The present invention also provides a method of populating a data structure stored at a user device with mobile

telecommunications network selection data (such as automatic network discovery and selection function data) , the method including setting an override element of the mobile

telecommunications network selection data indicating the extent to which mobile telecommunications network selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network. The data structure is typically populated in accordance with the invention when the user device is within a home network of the user device.

In one form of the invention, the said override element includes a first state and a second state, wherein: the override element being in the first state indicates that when mobile telecommunications network selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data provided by the home network should be used; and the override element being in the second state indicates that when mobile

telecommunications network selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data provided by the visited network should be used. In one form of the invention, the said override element includes a third state, wherein the override element being in the third state indicates that when mobile telecommunications network selection data has been provided by both the home network and the visited network, the mobile

telecommunications network selection data provided by the home network should be selected and, if the network selection data provided by the home network does not result in a suitable access network being provided to the user device, the mobile telecommunications network selection data provided by the visited network should be used.

The present invention also provides a server (such as an automotive network discovery and selection function server) comprising a first processor for controlling the editing or provision of mobile telecommunications network selection data (such as automatic network discovery and selection function data) for a user device, wherein the editing or provision of the mobile telecommunications network selection data includes setting an override element of the mobile telecommunications network selection data indicating the extent to which mobile telecommunications network selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network .

The said override element may indicate whether or not the mobile telecommunications network selection data of the visited network should override the mobile telecommunications network selection data of said home network. 1

The said override element may include at least two states, such as a first state, in which the mobile telecommunications network selection data provided by the home network is used and a second state, in which the mobile telecommunications network selection data provided by the visited network is used. The said override element may include a third state in which the mobile telecommunications network selection data provided by the home network is selected and, if the mobile telecommunications network selection data provided by the home network does not result in a suitable access network being provided to the user device, the mobile

telecommunications network selection data provided by the visited network is used. The present invention further provides a mobile communication device comprising: a first processor for determining whether mobile telecommunications network selection data stored at the mobile communication device has been provided by a home network of the user device; a second processor for

determining whether mobile telecommunications network

selection data stored at the mobile communication device has been provided by a visited network of the user device; and a third processor for determining the mobile telecommunications network selection data that should be used, in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, on the basis of a value of an override element of the mobile telecommunications network selection data. The various processors may be provided as separate processors, or the functionality of at least some of the processor may be combined into a single functional processor. In many forms of the invention, the mobile telecommunications network selection data is provided by the home network that provides the said override element. The said override element may indicate whether or not the mobile telecommunications network selection data of the visited network should override the mobile telecommunications network selection data of said home network.

telecommunications network selection data provided by the visited network is used.

The present invention further provides a data structure comprising mobile telecommunication network selection data, wherein the data structure includes an override element indicating the extent to which mobile telecommunications network selection data provided by a home network of a user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network. The data structure may be an automatic network discovery and selection function management object.

The said override element may be stored as a leaf of said management object (for example, stored below a policy node of said management object) . 1

The present invention also provides a computer program comprising: code (or some other means) for determining whether mobile telecommunications network selection data has been provided by a home network of a user device; code (or some other means) for determining, when the user device is roaming in a visited network, whether mobile

telecommunications network selection data has been provided by the visited network; code (or some other means) for determining, in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, the mobile

telecommunications network selection data that should be used on the basis of a value of an override element of the network selection data. The computer program may be a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer.

The present invention further provides a computer program comprising code (or some other means) for setting an override element of mobile telecommunications network selection data stored at a user device, the override element indicating the extent to which mobile telecommunications network selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network. The computer program may be a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer. 1

Exemplary embodiments of the invention are described below, by way of example only, with reference to the following numbered drawings . Figure 1 is a block diagram of a system in which the present invention may be used;

Figure 2 is a flow chart showing a network access selection algorithm;

Figure 3 is a block diagram showing a system in which the present invention may be used;

Figure 4 is a block diagram showing an exemplary ANDSF management object structure;

Figure 5 is a block diagram showing part of an exemplary ANDSF management object structure in accordance with an aspect of the present invention; and

Figure 6 is a flow chart showing an algorithm in

accordance with an aspect of the present invention.

Figure 4 is a block diagram showing an exemplary ANDSF management object (MO) structure. The structure of the management object 100 is the same as that set out in the technical specification 3GPP TS 24.312 V 8.1.0 produced by the 3rd Generation Partnership Project (available at

www.3gpp.org) . The management object 100 is supplied to a user device (such as the user device 2) by an ANDSF server (such as the ANDSF server 4) . As policies and rules are changed, the ANDSF server may update the data stored at the user device. The management object 100 is a tree of leaves and nodes. The tree starts at an interior node 102 (the root of the tree) , which provides a placeholder, under which an account for a fixed node may be provided. As shown in Figure 4, a number of nodes and leaves are provided under the node 102, some (but not all) of which are discussed below.

A Name leaf 104, a Policy node 106, a Discoverylnformation node 116, a UE_Location node 120 and an Ext node 122 are provided under the node 102, i.e. at the next level of the tree 100.

The name leaf 104 enables a name to be stored. The name stored at the name leaf 104 is not the formal name of the ANDSF MO. The name of the ANDSF MO is given at node 102. The name stored at the leaf 104 is a string and is generally the name that is shown to the user in any user interface associated with the tree 100.

The policy node 106 acts as a placeholder for policies for intersystem mobility. An interior node 108 is located under the policy node 106. Policies are stored under the node 106, with one policy being stored within each node 108. The ANDSF MO 100 shown in Figure 4 follows the OMA DM syntax for

Management Objects, such that the symbol +' after a node or leaf name (as with the node 108) indicates that one or more instances of the node or leaf may be present in any

particular ANDSF MO.

As shown in the algorithm 10 discussed above, the highest priority valid policy may be selected when a user is

attempting to connect to a network. The data stored at and under the policy node 106 can, amongst other functions, be used to determine the validity and priority of policies.

The Discoverylnformation node 116 acts as a root node for access network discovery information. As discussed above, access network discovery information (ANDI) can be used by a user device in detecting access networks specified in ANDSF policy rules. The access network discovery information is stored with the ANDSF MO tree 100 at and below the

Discoverylnformation node 116.

The UE_Location node 120 acts as a placeholder for data describing the current location of a user device. A range of location information is stored at nodes and leaves under the node 120, as shown in Figure 4, but not discussed further here.

The Ext node 122 is an interior node where vendor-specific information about the ANDSF MO is placed. Usually the vendor extension is identified by a vendor-specific name under the ext node. The tree structure under the vendor identifier may take many forms and is neither shown in Figure 4, nor

discussed further here.

As discussed above, the policy node 106 acts as a placeholder for policies for intersystem mobility, with the policies themselves being stored within the interior node 108. As described in the algorithm 10 discussed above, the highest priority valid policy (valid according to validity

conditions) is considered for network selection. The user device connects to the most preferred access network in the prioritized access list which user device is able to detect.

The rule structure shown in Figure 4 includes a rule priority leaf 110, a ValidityArea node 112 and a Roaming leaf 114. Other nodes and leaves are shown in Figure 4, but are not discussed further here.

The RulePriority leaf 110 represents the priority given to one particular rule and is represented as a numerical value. 1

The ValidityArea node 112 acts as a placeholder for location conditions for a particular rule. A range of area

information is stored at nodes under the node 112, as shown in Figure 4, but not discussed further here.

The Roaming leaf 114 indicates the roaming condition for the intersystem mobility policy rule. The rule is not valid unless the current user device roaming status (indicating whether or not the user device is roaming) matches the value in this field. VPLMN ANDSF would need to set this field always to 'roaming' while HPLMN ANDSF could set it either to 'roaming' or ^xnot roaming' . It is entirely possible that in some implementations of the ANDSF MO, this feature may be implemented differently.

As discussed above, the Discoverylnformation node 116 acts as a placeholder for access network discovery information. An interior node 118 is located under the Discoverylnformation node 116 and acts as a placeholder for one or more access network information elements. A range of discovery data is stored at nodes and leaves under the node 118, as shown in Figure 4, but not discussed further here. 3GPP specifications require that each PLMN can specify its own policy rules which are to be followed while a user device is roaming in the PLMN. Only a home PLMN can specify rules for other PLMNs and these are followed if the current PLMN does not provide its own rules. However, the inventors have realized that it is not currently clear how conflicts between policies provided by a H-ANDSF server and a V-ANDSF server should be resolved. Figure 5 shows a part of a management object, indicated generally by the reference numeral 200, in accordance with an aspect of the present invention. The management object 200 has its root at an interior node 202, which is similar to the interior node 102 described above. The management object 200 also includes a name leaf 204, a Policy node 206, a Discoverylnformation node 216 and a UE_location node 220 similar to the corresponding nodes described above.

In the same manner as the management object 100, the name leaf 204, Policy node 206, Discoverylnformation node 216 and the UE_location node 220 are all located below the interior node 202 of the tree 200.

The policy node 206 acts as a placeholder for policies for intersystem mobility. An interior node 208 is located under the policy node 206. The interior node 208 acts as a

placeholder for one or more intersystem mobility policy rules. As discussed above, multiple rules for any particular policy could be stored. The rule shown in Figure 5 shows a rule priority leaf 210 (similar to the rule priority leaf 110), a ValidityArea node 212 (similar to ValidityArea node 112) and a Roaming leaf 214 (similar to the Roaming leaf

114) . In addition, a VPLM Override leaf 230 is provided, as discussed further below. Other nodes and leaves may be provided, including (but not limited to) the nodes and leaves shown in the management object 100 described above with reference to Figure 4. Indeed, in some forms of the

invention, the management object 200 differs from the

management object 100 only in the provision of the VPLM

Override leaf 230. 1

The nodes and leaves of the management object 200 also have a variety of information stored under them, as discussed elsewhere and not shown in Figure 5.

The VPLMN Override leaf 230 enables an H-ANDSF server (such as the server 35) to indicate a co-operation mode to the user device. Currently one rule (policy) is selected to be an active rule among valid candidate rules. This can be a V- ANDSF provided rule or a H-ANDSF provided rule. If the user device is roaming, the V-ANDSF provided rules typically have precedence over H-ANDSF provided rules. The VPLMN Override leaf enables this default situation to be changed by allowing the HPLMN server to influence access technology selection even when the user device is roaming.

In one form of the invention, the VPLMN Override flag has three available values: DENIED, ALLOWED, and COOP. DENIED will prioritize HPLMN rules over VPLMN rules (i.e. does not allow the V-ANDSF policy to override the H-ANDSF policy) . ALLOWED prioritizes the VPLMN rules over the HPLMN rules (i.e. allows the V-ANDSF policy to override the H-ANDSF policy) . COOP indicates that the active HPLMN policy should be considered first and, in case this does not provide a suitable access technology to use, the active VPLMN policy is used. In this way, the HPLMN could, for example, favour a specific WLAN service provider but in case that provider is not available, the user device would follow the active VPLMN rule. The user device would need to select one active HPLMN rule and one active VPLMN rule and operate according to the VPLMN Override leaf in the active HPLMN rule. If there is no active HPLMN rule, then active VPLMN rule would be selected automatically . 1

Thus, the management object 200 enables the H-ANDSF server for a particular user device and the V-ANDSF server in the area in which the user device is roaming to co-operate. As usual, the H-ANDSF server defines ANDSF policies for the user device; the H-ANDSF also indicates (using the VPLM Override leaf 230) whether or not the relevant V-ANDSF server is allowed to override the policies provided by the H-ANDSF server . Figure 6 shows a flow chart, indicated generally by the reference numeral 300, showing an exemplary use of the principles of the present invention.

The flow chart provides an algorithm 300 for determining ANDSF policies to be used in a situation where a user device is roaming. The algorithm 300 starts at step 302, where it is determined whether or not an active H-ANDSF policy has been set for the user device. If an H-ANDSF policy has been set, the algorithm moves to step 304; otherwise the algorithm moves to step 308.

At step 304, it is determined whether or not an active V- ANDSF policy has been set for the user device at the relevant location. If an active V-ANDSF policy has been set, the algorithm moves to step 306; otherwise the algorithm moves to step 310.

At step 306, it has been determined that both an active H- ANDSF policy and an active V-ANDSF policy have been set for the current location of the user device. Accordingly, it is necessary to decide which policy should be used. At step 306, it is determined whether or not a VPLM Override flag (such as the flag 230) is present. If not, then the

algorithm moves to step 312 (where the V-ANDSF policy is allowed to override the H-ANDSF policy, which is the default action) . Otherwise, the algorithm considers the value of the VPLMN Override flag. Of course, a different default action could be specified in alternative embodiments of the

invention.

If the value of the VPLMN Override flag is DENIED, then the algorithm 300 moves to step 310 (where the H-ANDSF policy is applied, since the V-ANDSF policy has not been allowed to override the H-ANDSF policy) . If the value of the VPLMN

Override flag is ALLOWED, then the algorithm 300 moves to step 312 (where the V-ANDSF policy is allowed to override the H-ANDSF policy) . If the value of the VPLM Override flag is COOP, then the algorithm 300 moves to step 307.

At step 307, it is determined whether or not the active H- ANDSF policy has provided a suitable access network which is available for user device to connect to in current location. If so, the algorithm moves to step 310 (where the H-ANDSF policy is applied) ; otherwise the algorithm moves to step 312 (where the V-ANDSF policy is applied) .

At step 308, it is determined whether or not an active V- ANDSF policy has been set. If so, the algorithm moves to step 312; otherwise, the algorithm 300 terminates at step

314, since neither an H-ANDSF policy nor a V-ANDSF policy has been set for the user device at the relevant location.

At step 310, an H-ANDSF policy is applied. This is either because a V-ANDSF policy has not been set, because a V-ANDSF policy has been suppressed under the control of the H-ANDSF server, or because an H-ANDSF policy did not find a suitable access network. The algorithm then terminates at step 314. 1

At step 312, a V-ANDSF policy is applied. This is either because an H-ANDSF policy has not been set, or because although an H-ANDSF policy has been set, it has been

overridden by a V-ANDSF policy. The algorithm then

terminates at step 314.

In many forms of the invention, elements of the algorithm 300 are repeated periodically to ensure that the correct

decisions are made. For example, in the event that, at step 307, the HPLMN success output was "no", then the step 307 may be re-evaluated periodically to determine whether an HPLMN- preferred access point has become available.

As described above, the Override flag may have three states: ALLOWED, DENIED and COOP. In alternatives embodiments of the invention, the Override flag may have more or fewer than three states. For example, the Override flag may have just two states: ALLOWED (which allows the V-ANDSF policy to override the H-ANDSF policy) and DENIED (which does not allow the H-ANDSF policy to be overridden) . Moreover, the Override flag may be implemented using more than one flag to enable Boolean operations.

The present invention is intended for use with network selection data, such as ANDSF data. The exemplary formats of ANDSF data structures provided here are by way of example only. Many modifications to the data structures could be provided whilst still being within the scope of the present invention. For example, in the example described above, the PLMN Override flag 230 is provided as part of each policy entry. This is not essential. For example, there could be a single common flag provided by the H-ANDSF server, for example at the ANDSF root level. Furthermore, it should be noted that the ANDSF MO is likely to change over time. The present application is intended to encompass any such modifications to the ANDSF MO.

Moreover, the present invention is not restricted to ANDSF. The invention could be used with other forms of network selection data, such as WiMAX or 3GPP2 networks.

The embodiments of the invention described above are illustrative rather than restrictive. It will be apparent t those skilled in the art that the above devices and methods may incorporate a number of modifications without departing from the general scope of the invention. It is intended to include all such modifications within the scope of the invention insofar as they fall within the scope of the appended claims.

Claims

CLAIMS :

1. A method of using mobile telecommunications network selection data stored at a user device when the user device is within a visited network, the method comprising:

determining whether mobile telecommunications network selection data has been provided by a home network of the user device;

determining whether mobile telecommunications network selection data has been provided by a visited network of the user device; and

in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, determining the mobile

telecommunications network selection data that should be used on the basis of a value of an override element of the network selection data.

2. A method as claimed in claim 1, wherein said override element indicates whether or not the mobile

telecommunications network selection data of the visited network should override the mobile telecommunications network selection data of said home network.

3. A method as claimed in claim 1 or claim 2, wherein said override element includes at least two states, wherein, in a first state, the mobile telecommunications network selection data provided by the home network is used and, in a second state, the mobile telecommunications network selection data provided by the visited network is used.

4. A method as claimed in claim 3, wherein said override element includes a third state, wherein, in the third state, the mobile telecommunications network selection data provided by the home network is selected and, if the mobile telecommunications network selection data provided by the home network does not result in a suitable access network being provided to the user device, the mobile

5. A method of populating a data structure stored at a user device with mobile telecommunications network selection data, the method including setting an override element of the mobile telecommunications network selection data indicating the extent to which mobile telecommunications network

selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network.

6. A method as claimed in claim 5, wherein said override element indicates whether or not the mobile

7. A method as claimed in claim 5 or claim 6, wherein said override element includes a first state and a second state, wherein :

the override element being in the first state indicates that when mobile telecommunications network

selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data provided by the home network should be used; and

the override element being in the second state indicates that when mobile telecommunications network selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data provided by the visited network should be used .

8. A method as claimed in claim 7, wherein said override element includes a third state, wherein the override element being in the third state indicates that when mobile

telecommunications network selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data provided by the home network should be selected and, if the network selection data provided by the home network does not result in a suitable access network being provided to the user device, the mobile telecommunications network selection data provided by the visited network should be used.

9. A method as claimed in any preceding claim, wherein said mobile telecommunications network selection data is automatic network discovery and selection function data.

10. A server comprising a first processor for controlling the editing or provision of mobile telecommunications network selection data for a user device, wherein the editing or provision of the mobile telecommunications network selection data includes setting an override element of the mobile telecommunications network selection data indicating the extent to which mobile telecommunications network selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network.

11. A mobile communication device comprising: a first processor for determining whether mobile telecommunications network selection data stored at the mobile communication device has been provided by a home network of the user device;

a second processor for determining whether mobile telecommunications network selection data stored at the mobile communication device has been provided by a visited network of the user device; and

a third processor for determining the mobile telecommunications network selection data that should be used, in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, on the basis of a value of an override element of the mobile telecommunications network selection data .

12. A data structure comprising mobile telecommunication network selection data, wherein the data structure includes an override element indicating the extent to which mobile telecommunications network selection data provided by a home network of a user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network .

13. A data structure as claimed in claim 12, wherein

data structure is an automatic network discovery and

selection function management object.

14. A data structure as claimed in claim 13, wherein said override element is stored as a leaf of said management object .

15. A server as claimed in claim 10, a mobile communication device as claimed in claim 11 or a data structure as claimed in any one of claims 12 to 14, wherein the mobile

telecommunications network selection data is automatic network discovery and selection function data.

16. A computer program product comprising:

means for determining whether mobile

telecommunications network selection data has been provided by a home network of a user device;

means for determining, when the user device is roaming in a visited network, whether mobile

telecommunications network selection data has been provided by the visited network; and

means for determining, in the event that mobile telecommunications network selection data has been provided by both the home network and the visited network, the mobile telecommunications network selection data that should be used on the basis of a value of an override element of the network selection data.

17. A computer program product comprising means for setting an override element of mobile telecommunications network selection data stored at a user device, the override element indicating the extent to which mobile telecommunications network selection data provided by a home network of the user device and mobile telecommunications network selection data provided by a visited network should be used when the user device is roaming in the visited network.