WO2012077068A1

WO2012077068A1 - A system and method preventing accidental international roaming and enabling steering of subscribers

Info

Publication number: WO2012077068A1
Application number: PCT/IB2011/055517
Authority: WO
Inventors: Bahri Okuroglu
Original assignee: Turkcell Teknoloji Arastirma Ve Gelistirme Anonim Sirketi
Priority date: 2010-12-09
Filing date: 2011-12-07
Publication date: 2012-06-14
Also published as: TR201010286A2

Abstract

The present invention relates to a system (1) and method (100) enabling accidental international roaming prevention system(4) which prevents GSM subscribers who are crossing from transnational border (from border gate, by sea or by air) from getting service from operators of neighbor countries accidentally and outbound roamer steering system(5) which enables GSM operators to steer their subscribers to the operators desired abroad to co-operate in interaction with each other in an effective way. With this invention, it is ensured that more subscribers of HPLMN operator get service from preferred operators in neighbor countries by activating outbound roamer steering system(5) even in registration requests processed by the accidental international roaming prevention system(4).

Description

A SYSTEM AND METHOD PREVENTING ACCIDENTAL

INTERNATIONAL ROAMING AND ENABLING STEERING OF

SUBSCRIBERS

Technical Field

The present invention relates to a system and method enabling accidental international roaming prevention system which prevents GSM (Global System for Mobile Communications) subscribers from getting service from operators of neighbor countries accidentally and outbound roamer steering system which enables GSM operators to steer their subscribers to the operators desired in a foreign country to operate in an effective interaction.

Background of the Invention

GSM operators make roaming agreements with different operators in each country in order to enable their subscribers to get service abroad. Even if an operator has roaming agreement with more than one operator in any country, operators may specially want their subscribers to get service from some of their operators with whom they have agreement for certain reasons. The reason for this either may be a commercial reason such as the said operator provides a lower cost or a quality- based reason such as enabling subscribers to get better service depending on technical competencies of operators. In order to attain this objective, network- based outbound roamer steering systemoutbound roamer steering systems try to ensure that the subscribers get service from a foreign operator which is preferred by preventing registration requests of the subscribers in a specific scope and with specific techniques.

In order to prevent their subscribers from getting service from operators of neighbor countries in an accidental and unintentional way due to certain reasons while they are still within national boundaries, GSM operators prevent and delay registration requests of the subscribers in a specific scope and with specific techniques. This is called as accidental international roaming prevention system.

Both outbound roamer steering system and accidental international roaming prevention system operate on messages which are used by subscribers, getting service from abroad, in registration requests made from the operator abroad. Therefore, these two systems are in an inevitable interaction.

In both systems, the rejection of subscribers' registration requests is carried out within certain limits. It is allowed to approve the registration request of the subscriber to the operator abroad in cases such as when the registration request takes longer than the time limit specified or trying of foreign network/operator in a number more than the number limit specified.

Although there is not any interaction method which is generally defined between outbound roamer steering systems and systems of preventing accidental international roaming, when applications concerning these issues are examined it is seen that the most common configuration for operation of these two systems in interaction today is as follows:

If subscriber request to register an operator is received from a neighbor country, accidental international roaming prevention system evaluates subscriber's probability of making accidental international roaming. Information such as previous location of the subscriber are evaluated for the said transaction.

If no possibility of making accidental international roaming is detected, the registration request is continued to be processed by the outbound roamer steering system. If possibility of making accidental international roaming is detected, subscriber's request to register an operator is tried to be rejected or delayed without notifying it to the outbound roamer steering system. If subscriber's request to register an operator continues to be received persistently such that it will exceed the limits specified, the subscriber's request to register an operator is allowed.

Registration request of a subscriber whose probability of making accidental international roaming is detected in this way is terminated either by allowing the subscriber to return the main network (HPLMN - Home Public Land Mobile Network) or register the operator of a neighbor country successfully. The accidental international roaming prevention system allows the subscriber's request to register operators abroad after a certain point when it anticipates probability of subscriber's to cross from the border to a neighbor country really. In this case, for each subscriber crossing from the border to a neighbor country (from border gate, by sea or by air), neighbor operator for which the accidental international roaming prevention system allows the registration request can be an operator that is not preferred by the HPLMN operator. Systems which enable the accidental international roaming prevention system - the outbound roamer steering systems used today to operate in an interaction cannot solve this problem.

In interactions of the outbound roamer steering system - the accidental international roaming prevention system used today, message of registration request is allowed to reach HLR when limits configured by different number of parameters during rejection are reached. The outbound roamer steering system is never operated for a registration request which is detected to have a probability of accidental international roaming in such interaction systems (Figure 1).

Accidental international roaming prevention system cannot detect occurrence of accidental international roaming precisely by controls that it performs, it only detects that this may be a state of accidental international roaming. This state detected by the accidental international roaming prevention system either may really be a state of accidental international roaming or registration messages that are received from subscribers really crossing from border.

When interaction is not provided between the accidental international roaming prevention system and the outbound roamer steering system entirely, the outbound roamer steering system is not activated in certain cases and each subscriber crossing from the border to a neighbor country is tried to be prevented only by the accidental international roaming prevention system. In such cases, register to operators of neighbor country is allowed after limits set in the accidental international roaming prevention system because the subscriber is really in a neighbor country physically. Limits determined by the accidental international roaming prevention system may be number of foreign network tried by the subscriber or repetition of the registration request for a long time. The outbound roamer steering system is not activated because the first registration request received after these limits are reached is sent to the HLR (Home Location Register) of the HPLMN (Home Public Land Mobile Network) by being confirmed by the accidental international roaming prevention system. And this means that steering is not performed for subscribers crossing the border. This causes many subscribers to get service from non-preferred operators where there are border gates with high activity.

There may be preferential operator list written by HPLMN operator in SIM card (Subscriber Identity Module Card) of the operator. If there is an operator preferred for the country located in this list, it is tried to switch to the preferential operator in the list on the SIM card after a certain period of time even if the phone is registered to a non-preferred operator for a reason. However, this list on the SIM card is rather short and this list cannot be filled such that it will comprise all operators preferred by operators. When there is no preferential operator belonging to the country in the list on the SIM card and the subscriber is registered to a non-preferred operator for a reason, most of the operators crossing from the border gate to a neighbor country remain in a non-preferred operator because the phone does not make any effort to exit this network automatically.

The United States patent document no. US2006135160A1 discloses a system and method used for registering a subscriber, who is in a region having multiple overlapping wireless cellular networks, to a Home Public Mobile Network (HPMN). The invention disclosed in the said document detects potential registration of the subscriber with a Neighboring Visited Public Mobile Network (NPMN), although the HPMN may be present in the region, in response to a registration request from the NPMN and attempts a pre-defined number of rejections upon successful detection. A accidental international roaming prevention system is described in the said document and co-operation of accidental international roaming prevention system and outbound roamer steering system is not mentioned. The United States patent document no. US7072651B2 discloses a system and apparatus for redirecting wireless network traffic. Registration attempt of roaming mobile station to a non-preferred network is determined and the said station is steered to a preferred network. The traffic redirection network entity provided in the said system has a traffic redirection node, a traffic redirection application and a traffic redirection probe. Co-operation of accidental international roaming prevention system and outbound roamer steering system is not mentioned in the said document.

The United States patent document no. US2008020756A1 discloses a system, method and computer programme for redirecting roaming traffic of a subscriber in the event that the subscriber is associated with the visitied network. The method used in the system comprises steps of: retrieving a first transaction ID by passively monitoring a registration message intended for a home location information database; retrieving a second transaction ID by passively monitoring an update message originating from the home location information database; sending an abort message to the home location information database with the second transaction ID to restrict any further transactions with the home location information database using the second transaction ID; and sending a registration response message to a visited location information database with the first transaction ID to restrict the subscriber from registering with the visited location information database, based on the subscriber's profile information. Co-operation of accidental international roaming prevention system and outbound roamer steering system is not mentioned in the said document. The United States patent document no. US7139570B2 discloses selection of a network preferred for roaming. In the system disclosed in the said document, there is a remote preference unit which influences visited network selection by roaming mobile units. This unit has a detection unit which detects roaming activity of mobile units; a database which is used by roaming mobile units in order to select network and indicates preferred networks; and an output unit which is associated with the detection unit and the database and influences network selection of roaming mobile units. The system disclosed in the said document relates to connection of roaming subscribers to a preferred operator and co-operation of accidental international roaming prevention system and outbound roamer steering system is not mentioned in the said document.

Summary of the Invention

Objective of the invention is to realize a system and method enabling accidental international roaming prevention system which prevents GSM subscribers, who are crossing from transnational border (from border gate, by sea or by air), from getting service via operators of neighbor countries accidentally and outbound roamer steering system which enables GSM operators to steer their subscribers to the operators desired abroad to co-operate.

Another objective of the invention is to realize a system and method enabling more subscribers of HPLMN operator to get service from preferred operators in neighbor countries by activating outbound roamer steering system even in registration requests processed by accidental international roaming prevention system.

Detailed Description of the Invention

"A System and Method Preventing Accidental International Roaming and Enabling Steering of Subscribers" realized to fulfill the objectives of the present invention is shown in figures attached, in which:

Figure 1 is a flowchart of a method used in an embodiment of the prior art.

Figure 2 is a schematic block diagram of the inventive system.

Figure 3 is a flowchart of a method enabling the inventive system to operate.

The components illustrated in the figures are individually numbered, where the numbers refer to the following: 1. System

2. Mobile device

21. SIM card (Subscriber Identity Module Card)

3. HPLMN (Home Public Mobile Network)

31. VLR (Visitor Location Register)

32. HLR (Home Location Register) 33. MSC (Mobile Switching Center)

4. Accidental international roaming prevention system

5. Outbound roamer steering system

100. Method

A. VPLMN (Visitor Public Mobile Network)

B. VLR (Visitor Location Register)

C. MSC (Mobile Switching Center)

System which prevents GSM subscribers from getting service from operators of neighbor countries accidentally and enables GSM operators to be steered to operators desired abroad (1) comprises:

at least one mobile device (2) which has at least one SIM card (21); at least one home public mobile network (3) which has at least one visitor location register (31) that is a database where subscriber information are kept under registration temporarily, at least one home location register (32) that is a main database where all subscriber information are kept under registration permanently, at least one mobile switching center (33) that is associated with the visitor location register (31) and the home location register (32) and acts as a terminal; at least one accidental international roaming prevention system (4) which prevents GSM subscribers from getting service from operators of neighbor countries accidentally; and

at least one outbound roamer steering system (5) which can operate together with the accidental international roaming prevention system (4) or independently of the accidental international roaming prevention system (4), enables GSM operators to steer their subscribers to desired operators in foreign countries that are neighbor and/or not neighbor in embodiments where it operates independently of the accidental international roaming prevention system (4), and enables GSM operators to steer their subscribers to desired operators in foreign countries that are neighbor by being activated by the accidental international roaming prevention system (4) depending on whether there is probability of accidental international roaming state in embodiments where it operates together with the accidental international roaming prevention system (4) (Figure 2).

In the preferred embodiment of the invention, the mobile device (2) is a cell phone and it comprises at least one SIM card (21). The home public mobile network (3) is a network whereto the subscriber belongs in fact.

The visitor public mobile network (A) is a visitor network from which the subscriber gets service when s/he is out of her/his network.

The home location register (32, C) is a central database and it carries out transaction of keeping all information of a subscriber in GSM network.

The mobile switching center (33, D) carries out transactions of telephone switching by inspecting calls of the network where it is located with other networks and data systems.

The visitor location register (31, B) carries out transaction of keeping registration of subscribers who are in this area physically, in the GSM network temporarily. When the subscriber enters coverage area of the mobile switching center (C) in the visitor public mobile network (A), the visitor location register (31) in the visitor public mobile network (A) requests subscriber information from the home location register (32) in the home public mobile network (3). When the home location register (32) approves this request, it enables new calls to reach the visitor location register (B) in the visitor public mobile network (A) by changing active VLR information for the subscriber in the database. This infrastructure is defined by GSM standards and the message sent by the visitor location register (B) to the home location register (32) is an UpdateLocation (UL) MAP (Mobile Application Part) message. The said message flow is shown in Table 1. The visitor location register (B) stores information of the said subscriber is stored temporarily as long as the subscriber is in coverage area.

Table 1: Message flow of location update between the visitor location register

(31, B) and the home location register (32)

VL fo d)

The accidental international roaming prevention system (4) enables the message coming from the subscriber to reach the home location register (32) or to reject the incoming message depending on whether there is probability of accidental international roaming state. In addition, the accidental international roaming prevention system (4) activates the outbound roamer steering system (5) depending on whether there is probability of accidental international roaming state.

The outbound roamer steering system (5) enables subscribers to get service from foreign operators preferred by the operator, by allowing or not allowing the message coming from the subscriber to reach the home location register (32) like the accidental international roaming prevention system (4).

When the mobile device (2) finds out that its SIM card (21) is not within the coverage of the home public mobile network (3) while it is in international roaming, it tries to get service from a network by selecting GSM networks which have coverage with specific algorithms i.e. one of visitor public mobile networks (A). If the visitor public mobile network (A) selected has a roaming agreement with the home public mobile network (3) the visitor location register (B) of the visitor public mobile network (A) sends UpdateLocation (UL) message of the home public mobile network (3) to the home location register (32), upon this request of the subscriber. This request is accepted or rejected as a result of specific controls such as whether the subscriber is enabled for roaming or not. In order to both prevent accidental international roaming and steer the subscriber to a preferred visitor public mobile network (A), the accidental international roaming prevention system (4) and the outbound roamer steering system (5) intervene this message flow by co-operating in an interactive manner and try to make the subscriber to return the home public mobile network (3) or steer the subscriber to a preferred visitor public mobile network (A).

In order to illustrate the said steering or the rejection carried out by the accidental international roaming prevention system (4), message flow for steering a subscriber to a preferred operator by the outbound roamer steering system (5) is shown in Table 2. Table 2: Message flow for steering a subscriber to a preferred operator by the outbound roamer steering system (5)

VL

F

'ne l - non-preferred 1 AYi

The accidental international roaming prevention system (4) tries to make subscribers to return the home public mobile network (3) by rejecting registration requests similar to Table 2. Both the accidental international roaming prevention system (4) and the outbound roamer steering system (5) carry out the said rejection within certain limits. These limits are set by the operator operating the system (1) and its main objective is not to put subscribers in a position where they cannot get service unnecessarily. For this purpose, different limits which are adjustable can be set for the rejection. The said limits can be illustrated as follows:

Maximum period of registration trial: In the accidental international roaming prevention system (4), registration requests of the subscriber can be rejected until the time started when the subscriber sends first message to register the visitor public mobile network (A) reaches the configured value whereas in the outbound roamer steering system (5), registration requests of the subscriber can be rejected until the time started when the subscriber sends first message to register the visitor public mobile network (A) reaches the configured value, as long as the requests continue coming from a non-preferred network, and first message which is received after this period of time is accepted. Two different copies of this parameter, called TKUDOS and TAYS, can be kept for the accidental international roaming prevention system (4) and the outbound roamer steering system (5) if this parameter is called as T.

Maximum number of rejectable network: When the registration request of the subscriber is rejected the subscriber tries to register from another network having coverage after s/he repeats three more times from the same network. By counting the number of networks tried in this way, first registration request received is accepted when this number exceeds the N value configured. Two different copies of this parameter, called NKUDOS and NAYS, can be kept for the accidental international roaming prevention system (4) and the outbound roamer steering system (5). Limits to be applied for the accidental international roaming prevention system (4) activates the outbound roamer steering system (5) are not limited to the said examples. The inventive system (1) and the method (100) enabling the system (1) to operate are independent of the said parameters.

The method which prevents GSM subscribers from getting service from operators of neighbor countries accidentally and enables GSM operators to be steered to operators desired in foreign countries (1) comprises steps of:

- receiving message of registration request (101);

- controlling whether the subscriber is rejected before (102);

controlling whether the message of registration request is received from a neighbor country if it is detected that the subscriber is not rejected before at the step of controlling whether the subscriber is rejected before (102)

(103) ;

- activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the message of registration request is not received from a neighbor country at the step of controlling whether the message of registration request is received from a neighbor country (103)

(104) ;

execution of accidental international roaming detection algorithm if it is detected that the message of registration request is received from a neighbor country at the step of controlling whether the message of registration request is received from a neighbor country (103) (105);

interrogating whether there is probability of accidental international roaming (106); activating the outbound roamer steering system (5) for the message sent by the subscriber (in other words, going to step 104) if it is detected that there is no probability of accidental international roaming at the step of interrogating whether there is probability of accidental international roaming (106) (104);

rejecting the registration request if it is detected that there is probability of accidental international roaming at the step of interrogating whether there is probability of accidental international roaming (106) (107);

marking the subscriber as rejected (108);

interrogating whether the first threshold for rejection limit value is reached if it is detected that the subscriber is rejected before at the step of controlling whether the subscriber is rejected before (102) (109);

allowing registration transaction of the subscriber to the visitor public mobile network (A) by allowing the message of registration request to reach the home location register (32) of the home public mobile network (3) if it is detected that the first threshold for rejection limit value is reached at the step of interrogating whether the first threshold for rejection limit value is reached (110);

interrogating whether the second threshold for rejection limit value is reached if it is detected that the first threshold for rejection limit value is not reached at the step of interrogating whether the first threshold for rejection limit value is reached (109) (111);

rejecting the registration request (in other words, going to step 107) if it is detected that the second threshold for rejection limit value is not reached at the step of interrogating whether the second threshold for rejection limit value is reached (111) (107);

activating the outbound roamer steering system (5) for the message sent by the subscriber (in other words, going to step 104) if it is detected that the second threshold for rejection limit value is reached at the step of interrogating whether the second threshold for rejection limit value is reached (111) (Figure 3).

The subscriber may try to get service from the visitor public mobile network (A) in whose coverage area it is located while s/he is in places close to country borders or about to cross country borders. Therefore, the mobile device (2) sends message of registration request to the visitor public mobile network (A). When the subscriber enters coverage area of the mobile switching center (C) in the visitor public mobile network (A), the visitor location register (B) in the visitor public mobile network (A) requests subscriber information from the home location register (32) in the home public mobile network (3). Therefore, the visitor location register (B) sends the message of registration request to the home location register (32) in order to get information of the subscriber from the home location register (32) in the home public mobile network (3).

The inventive system (1) enables this message of registration request, which is sent by the visitor location register (B) in the visitor public mobile network (A), to initially reach the accidental international roaming prevention system (4) without going to the home location register (32).

The accidental international roaming prevention system (4) receives the message sent by the visitor location register (B) (101). Then, by looking this message, the accidental international roaming prevention system (4) examines whether the subscriber has previously made registration request to the same visitor public mobile network (A) and as a result of this, whether this registration request is rejected (102). In other words, the accidental international roaming prevention system (4) examines whether the registration request of the subscriber to the said visitor public mobile network (A) has been already rejected. If the accidental international roaming prevention system (4) detects that the subscriber has not been already rejected, it controls whether the message of registration request is received from the visitor location register (B) of the visitor public mobile network (A) in a neighbor country (103).

If the accidental international roaming prevention system (4) detects that the message of registration request is not received from the visitor public mobile network (A) of a neighbor country, it activates the outbound roamer steering system (5) for the said message (104).

After the outbound roamer steering system (5) is activated it decides whether the subscriber will be steered to another network as a result of its own algorithms. If the outbound roamer steering system (5) decides that the subscriber will be steered to another network in consequence of the said decision-making transaction, it rejects the registration request of the subscriber to the visitor public mobile network (A) and marks the subscriber as rejected for the said visitor public mobile network (A). If the outbound roamer steering system (5) decides that the subscriber will not be steered to another network, it allows registration transaction of the subscriber to the visitor public mobile network (A) by enabling the message of registration request to reach the home location register (32) of the home public mobile network (3).

The outbound roamer steering system (5) may carry out an algorithm as follows for the said decision-making transaction: The outbound roamer steering system (5) interrogates whether the message is received from a preferred visitor public mobile network (A). If the message is received from a visitor public mobile network (A) which is not preferred by the home public mobile network (3), the outbound roamer steering system (5) rejects the registration request. The subscriber whose registration request is rejected is marked as rejected by the outbound roamer steering system (5) for the said visitor public mobile network (A). If the message is received from a visitor public mobile network (A) which is preferred by the home public mobile network (3), the outbound roamer steering system (5) allows registration transaction of the subscriber to the visitor public mobile network (A) by enabling the message of registration request to reach the home location register (32) of the home public mobile network (3). The inventive system (1) and the method (100) enabling the system (1) to operate relate to activation of outbound roamer steering systems (5) which are currently existing and they are independent of algorithms which are used by outbound roamer steering systems (5) within their structures.

If the accidental international roaming prevention system (4) detects that message of registration request is received from the visitor location register (B) of the visitor public mobile network (A) of the neighbor country, it operates detection algorithm of accidental international roaming (105). The said algorithm controls whether there is probability of accidental international roaming, for example, by taking into consideration parameters such as last location and status of the mobile device (2). The inventive system (1) and the method (100) enabling the system (1) to operate relate to operation of currently existing systems of preventing accidental international roaming (4) and the outbound roamer steering systems (5) with each other in an effective interaction and they are independent of algorithms which are used by the said systems (4, 5) within their structures. In other words, the inventive system (1) is independent of transactions of how the accidental international roaming prevention system (4) detects probability of occurrence of an accidental international roaming and how the outbound roamer steering system (5) decides whether to steer the subscriber.

If the accidental international roaming prevention system (4) does not detect probability of occurrence of an accidental international roaming it activates the outbound roamer steering system (5) (104). If the accidental international roaming prevention system (4) detects probability of occurrence of an accidental international roaming, the message of registration request sent by the subscriber is rejected by the accidental international roaming prevention system (4) by considering that the subscriber is still within national borders (107). The subscriber whose registration request is rejected is marked as rejected (108).

In the inventive system (1) and the method (100) enabling the system to operate, both the accidental international roaming prevention system (4) and the outbound roamer steering system (5) carry out rejection of registration request of the subscriber to the visitor public mobile network (A) within certain limits. These limits are set by the operator operating the system (1) and and its main objective is not to put subscribers in a position where they cannot get service unnecessarily. For this purpose, different limits which are adjustable can be set for the rejection. The said limits are preferably two types such as "maximum period of registration trial" ve "maximum number of rejectable network".

Maximum period of registration trial: Registration requests of the subscriber can be rejected until the time started when the subscriber sends first message to register the visitor public mobile network (A) reaches the configured value whereas first message which is received after this period of time is accepted. Two different copies of this parameter, called TKUDOS and TAYS, can be kept for the accidental international roaming prevention system (4) the outbound roamer steering system (5) if this parameter is called as T.

Maximum number of rejectable network: When the registration requests of the subscriber are rejected the subscriber tries to register from another network having coverage after s/he repeats three more times from the same network. By counting the number of networks tried in this way, first registration request received is accepted when this number exceeds the N value configured. Two different copies of this parameter, called NKUDOS and NAYS, can be kept for the accidental international roaming prevention system (4) activates the outbound roamer steering system (5).

In the inventive system (1), there are two different parameter sets such as parameter_set_KuDos and parameter_set_AYs and there are different parameters such as T nd N in each parameter set. For the parameter_setK_UDos of the inventive system (1) and the method (100) and the accidental international roaming prevention system (4) essentially, two different parameter sets such as parameter_set_KuDosi (first threshold) and parameter_set_KuDos2 (second threshold) are kept. Among the said parameter sets, parameter values of the parameter_setK_UDosi are greater than the parameter values of the parameter_setK_UDos2- When the accidental international roaming prevention system (4) decides that limits are reached after controls of the parameter setK_UDosi, it allows registration transaction of the subscriber to the visitor public mobile network (A) by enabling the message of registration request to reach the home location register (32). Whereas, when the accidental international roaming prevention system (4) decides that limits are reached after controls of the parameter_set_KuDos2 it activates the outbound roamer steering system (5) instead of transmitting this message of registration request to the home location register (32). Thus, the outbound roamer steering system (5) can decide whether the message will continue to reach the home location register (32) or being rejected depending on whether the operator where the message arrives from is a preferred operator.

While the message sent by the visitor location register (B) is being examined, the accidental international roaming prevention system (4) interrogates whether the parameter setK_UDosi i.e. the first threshold for rejection limit value is reached (109). If the accidental international roaming prevention system (4) decides that the first threshold for rejection limit value is reached after controls of the parameter setKUDosi, it allows registration transaction of the subscriber to the visitor public mobile network (A) by allowing the message of registration request to reach the home location register (32) of the home public mobile network (3) (110).

If the accidental international roaming prevention system (4) decides that the first threshold for rejection limit value is reached after controls of the parameter_set_KuDosi, it interrogates whether the parameter_set_KuDos2 i.e. the second threshold for rejection limit value is reached (111).

If the accidental international roaming prevention system (4) decides that the second threshold for rejection limit value is reached after controls of the parameter_set_KuDosi, it activates the outbound roamer steering system (5) (104).

If the accidental international roaming prevention system (4) decides that the second threshold for rejection limit value is not reached after controls of the parameter setKUDosi, the accidental international roaming prevention system (4) rejects the message of registration request sent by the subscriber (107). Then, the accidental international roaming prevention system (4) marks the subscriber whose registration request is rejected as rejected (108). Assume that, there is only T parameter among the parameter set for illustrating the operation of the inventive system (1) and the parameters are given as follows:

- TAYS: 4

- TKUDOSl : 4

- TKUDOS2: 2 Message flow and operations with these parameters can be illustrated as follows: Registration attempt is received from a visitor public mobile network (A) in a neighbor country. The accidental international roaming prevention system (4) rejects this request by detecting probability of an accidental international roaming. Registration attempt is received from the same visitor public mobile network (A) for three more times and the accidental international roaming prevention system (4) rejects all of them again. Then, registration attempt is received from another visitor public mobile network (A) in a neighbor country. The accidental international roaming prevention system (4) rejects this request too. Registration attempt is received from the same visitor public mobile network (A) for three more times and the accidental international roaming prevention system (4) rejects all of them again. Then, registration attempt is received from the third visitor public mobile network (A) which is not preferred in the neighbor country. The outbound roamer steering system (5) is activated because it is the second threshold value and exceeded, however, the outbound roamer steering system (5) rejects this request because it is not preferred. Registration attempt is received from the same visitor public mobile network (A) for three more times and all of them are rejected again. Registration attempt is received from the fourth visitor public mobile network (A) which is preferred. The outbound roamer steering system (5) becomes activated and this time it transmits this request to the home location register (32). Consequently, transaction of preventing accidental international roaming fails because the subscriber has probably crossed the neighbor country physically. But the subscriber is still enabled to register a preferred operator. If there was only one parameter of preventing accidental international roaming the subscriber would be registered to the third visitor public mobile network (A). In the inventive system (1), when the second threshold value is exceeded the accidental international roaming prevention system (4) activates the outbound roamer steering system (5) for this message instead of transmitting it to the home location register (32). Thus, the subscriber can decide whether the message will continue to reach the home location register (32) or being rejected depending on whether the visitor public mobile network (A) where the message arrives is preferred.

In preferred embodiment of the invention, all parameters resume after the outbound roamer steering system (5) is activated. If parameter of the outbound roamer steering system (5) is defined as two as well when the abovementioned example is taken into account for the said embodiment, when the two different networks (A) are rejected by the accidental international roaming prevention system (4) the outbound roamer steering system (5) allows the subscriber request to reach the home location register (32) because the limits are attained regardless of whether the new network (A) where the message of registration request arrives is preferred or not.

In another embodiment of the invention, all or specified parameters are set to zero after the outbound roamer steering system (5) is activated. Even if parameter of the outbound roamer steering system (5) is defined as two when the abovementioned example is taken into account for the said embodiment, the outbound roamer steering system (5) counts the rejected networks (A) starting from zero while two different networks (A) are rejected by the accidental international roaming prevention system (4). Thus, the outbound roamer steering system (5) decides what to do for the registration request by considering whether it is preferred or not.

The accidental international roaming prevention system (4) provided in the inventive system (1) is configured to carry out transactions of:

- receiving the message of registration request;

- controlling whether the subscriber is rejected before; - controlling whether the message of registration request is received from a neighbor country if it is detected that the subscriber is not rejected before;

- activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the message of registration request is not received from a neighbor country;

- execution of accidental international roaming detection algorithm if it is detected that the message of registration request is received from a neighbor country;

- interrogating whether there is probability of accidental international roaming;

- activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that there is no probability of accidental international roaming;

- rejecting the registration request if it is detected that there is probability of accidental international roaming;

- marking the subscriber as rejected;

- interrogating whether the first threshold for rejection limit value is reached if it is detected that the subscriber is rejected before;

- allowing registration transaction of the subscriber to the visitor public mobile network (A) by allowing the message of registration request to reach the home location register (32) of the home public mobile network (3) if it is detected that the first threshold for rejection limit value is reached;

- interrogating whether the second threshold for rejection limit value is reached if it is detected that the first threshold for rejection limit value is not reached;

- rejecting the registration request if it is detected that the second threshold for rejection limit value is not reached; - activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the second threshold for rejection limit value is reached. With the inventive system (1) and method (100), accidental international roaming prevention system (4) which prevents GSM subscribers who are crossing from transnational border (from border gate, by sea or by air) from getting service from operators of neighbor countries accidentally and outbound roamer steering system (5) which enables GSM operators to steer their subscribers to the operators desired abroad are enabled to co-operate in an interactive manner.

In the inventive system (1) and the method (100) enabling this system (1) to operate, it is ensured that more subscribers of home public mobile network (3) operator get service from preferred operators in neighbor countries by activating outbound roamer steering system (5) even in registration requests processed by accidental international roaming prevention system (4).

The method (100) used in the inventive system (1) can be applied to all kinds of accidental international roaming prevention system (4) and outbound roamer steering system (5).

It is possible to develop various embodiments of "a system (1) and method (100) preventing accidental international roaming and enabling steering of subscribers", it cannot be limited to examples disclosed herein and it is essentially according to claims.

Claims

A method (100) which prevents GSM subscribers from getting service from operators of neighbor countries accidentally and enables GSM operators to be steered to operators desired foreign countries (1) characterized by steps of:

- receiving message of registration request (101);

- controlling whether the subscriber is rejected before (102);

(103) ;

(104) ;

interrogating whether there is probability of accidental international roaming (106);

- activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that there is no probability of accidental international roaming at the step of interrogating whether there is probability of accidental international roaming (106) (104);

- rejecting the registration request if it is detected that there is probability of accidental international roaming at the step of interrogating whether there is probability of accidental international roaming (106) (107);

26 - marking the subscriber as rejected (108);

- rejecting the registration request if it is detected that the second threshold for rejection limit value is not reached at the step of interrogating whether the second threshold for rejection limit value is reached (111) (107);

- activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the second threshold for rejection limit value is reached at the step of interrogating whether the second threshold for rejection limit value is reached (111) (104).

A method (100) according to Claim 1, characterized in that outbound roamer steering system (5) decides whether the subscriber will be steered to another network as a result of its own algorithms after it is activated

A method (100) according to Claim 2, characterized in that if the outbound roamer steering system (5) decides that the subscriber will be steered to another network in consequence of decision-making transaction, the

27 registration request of the subscriber to the visitor public mobile network (A) is rejected by the outbound roamer steering system (5) and the subscriber is marked as rejected for the said visitor public mobile network (A).

A method (100) according to Claim 2, characterized in that if the outbound roamer steering system (5) decides that the subscriber will not be steered to another network in consequence of decision-making transaction, registration transaction of the subscriber to the visitor public mobile network (A) is allowed by enabling the message of registration request of the subscriber to reach the home location register (32) of the home public mobile network (3) by the outbound roamer steering system (5).

A method (100) according to Claim 2 to 4, characterized in that the outbound roamer steering system (5) which uses an algorithm as follows for transaction of whether steering the subscriber to another network:

- interrogating whether the message is received from a preferred visitor public mobile network (A);

- rejecting the registration request if the message is received from a visitor public mobile network (A) which is not preferred by the home public mobile network (3);

- marking the subscriber whose registration request is rejected as rejected for the said visitor public mobile network (A);

- allowing registration transaction of the subscriber to the visitor public mobile network (A) by enabling the message of registration request to reach the home location register (32) of the home public mobile network (3) if the message is received from a visitor public mobile network (A) which is preferred by the home public mobile network (3).

A method (100) according to any of the preceding claims, characterized in that the algorithm at the step of execution of accidental international roaming

28 detection algorithm (109) controls whether there is probability of an accidental international roaming by taking into consideration parameters such as last location and status of the mobile device (2). 7. A method (100) according to any of the preceding claims, characterized in that rejection of registration request of the subscriber to the visitor public mobile network (A) in both accidental international roaming prevention system (4) and the outbound roamer steering system (5) is carried out within certain limits.

8. A method (100) according to Claim 7, characterized in that limits in rejection of registration request of the subscriber to the visitor public mobile network (A) are in two types such as "maximum period of registration trial" ve "maximum number of rejectable network".

9. A method (100) according to Claim 8, characterized in that in the maximum period of registration trial: registration requests of the subscriber can be rejected until the time started when the subscriber sends first message to register the visitor public mobile network (A) reaches the configured value whereas in the outbound roamer steering system (5); registration requests of the subscriber can be rejected until the time started when the subscriber sends first message to register the visitor public mobile network (A) reaches the configured value, as long as the requests continue coming from a non- preferred network; and first request which is received after this period of time is accepted; and two different copies of this parameter, called TKUDOS and

TAYS, can be kept for the accidental international roaming prevention system (4) and the outbound roamer steering system (5).

10. A method (100) according to Claim 8 or 9, characterized in that in the maximum number of rejectable network: when the registration requests of the

29 subscriber is rejected, accepting first registration request received by counting the number of networks tried as a consequence that the subscriber tries to register from another network having coverage after s/he repeats three more times from the same network when this number exceeds the N value configured; and two different copies of this parameter, called NKUDOS and

NAYS, can be kept for the accidental international roaming prevention system (4) and the outbound roamer steering system (5).

11. A method (100) according to any of the preceding claims, characterized in that there are two different parameter sets such as parameter_setKUDos and parameter set_AYs for the accidental international roaming prevention system (4) and the outbound roamer steering system (5), and there are different parameters such as T nd N in each parameter set. 12. A method (100) according to Claim 1 1 , characterized in that two different parameter sets such as parameter_set_KuDosi (first threshold) and parameter_set_KuDos2 (second threshold) are kept for the parameter_set_KuDos of the accidental international roaming prevention system (4). 13. A method (100) according to Claim 12, characterized in that parameter values of the parameter_setKUDosi are greater than the parameter values of the parameter_set_KuDos2 ·

14. A method (100) according to any of the preceding claims, characterized in that all parameters resume after the outbound roamer steering system (5) is activated.

15. A method (100) according to Claim 1 to 13, characterized in that all or specified parameters are set to zero after the outbound roamer steering system (5) is activated.

30

16. A system (1) which prevents GSM subscribers from getting service from operators of neighbor countries accidentally and enables GSM operators to be steered to operators desired abroad (1); comprising

at least one mobile device (2) which has at least one SIM card (21); at least one home public mobile network (3) which has at least one visitor location register (31) that is a database where subscriber information are kept under registration temporarily, at least one home location register (32) that is a main database where all subscriber information are kept under registration permanently, at least one mobile switching center (33) that is associated with the visitor location register (31) and the home location register (32) and acts as a terminal; at least one accidental international roaming prevention system (4) which prevents GSM subscribers from getting service from operators of neighbor countries accidentally; and characterized by

at least one outbound roamer steering system (5) which can operate together with the accidental international roaming prevention system (4) or independently of the accidental international roaming prevention system (4), enables GSM operators to steer their subscribers to desired operators in foreign countries that are neighbor and/or not neighbor in embodiments where it operates independently of the accidental international roaming prevention system (4), and enables GSM operators to steer their subscribers to desired operators in foreign countries that are neighbor by being activate by the accidental international roaming prevention system (4) depending on whether there is probability of accidental international roaming state in embodiments where it operates together with the accidental international roaming prevention system (4).

31 A system (1) according to Claim 16, characterized by accidental international roaming prevention system (4) which is configured to carry out transactions of:

receiving the message of registration request;

controlling whether the subscriber is rejected before;

controlling whether the message of registration request is received from a neighbor country if it is detected that the subscriber is not rejected before;

activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the message of registration request is not received from a neighbor country;

execution of accidental international roaming detection algorithm if it is detected that the message of registration request is received from a neighbor country;

- marking the subscriber as rejected;

32 - interrogating whether the second threshold for rejection limit value is reached if it is detected that the first threshold for rejection limit value is not reached;

- rejecting the registration request if it is detected that the second threshold for rejection limit value is not reached;

activating the outbound roamer steering system (5) for the message sent by the subscriber if it is detected that the second threshold for rejection limit value is reached. 18. A system (1) according to Claim 16 or 17, characterized by mobile device which is cell phone.

19. A system (1) according to any of Claim 16 to 18, characterized by outbound roamer steering system (5) which decides whether the subscriber will be steered to another network as a result of its own algorithms, after it is activated.

20. A system (1) according to Claim 19, characterized by outbound roamer steering system (5) which rejects registration request of the subscriber to the visitor public mobile network (A) and enables to marks the subscriber as rejected for the said visitor public mobile network (A) if it decides that the subscriber will be steered to another network in consequence of the decisionmaking transaction. 21. A system (1) according to Claim 19 to 20, characterized by outbound roamer steering system (5) which allows registration transaction of the subscriber to the visitor public mobile network (A) by enabling the message of registration request to reach the home location register (32) of the home public mobile network (3) if it decides that the subscriber will not be steered to another network in consequence of the decision-making transaction.

33

22. A system (1) according to any of Claim 19 to 21, characterized by outbound roamer steering system (5) which uses an algorithm as follows for transaction of whether steering the subscriber to another network:

23. A system (1) according to Claim 16 to 22, characterized by subscriber accidental international roaming prevention system (4) which controls whether there is probability of accidental international roaming by taking into consideration parameters such as last location and status of the mobile device (2) with the algorithm in the operation transaction of the detection algorithm of accidental international roaming.

34