GB2344490A

GB2344490A - Using prepaid services provided by the home network when roaming in a separate network

Info

Publication number: GB2344490A
Application number: GB9826384A
Authority: GB
Inventors: Vishram Laliji Hirani; Piotr Kazimierz Grzesik; Ralph James Edwards; Howard James Spragg
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1998-12-01
Filing date: 1998-12-01
Publication date: 2000-06-07
Anticipated expiration: 2018-12-01
Also published as: GB2344490B; CN1255811A; CN1126386C; GB2344490A8; GB9826384D0

Abstract

The visiting mobile switching centre VMSC 12 of a network 4 which does not support prepaid services receives a call request from a roaming subscriber 1. The VMSC then obtains subscriber information including a preferred interexchange carrier (PIC) which indicates whether the subscriber uses pre-paid services. If the subscriber does use pre-paid services the requested call is routed via a dedicated pre-paid switching centre 16 in the subscriber's home network 2. A carrier identification code (CIC) is generated indicating that the call should be routed through the pre-paid switching centre and the CIC information is supplied with the called party number to the home network for call routing. Calls to the subscriber who uses the pre-paid services are also routed via the pre-paid switching centre.

Description

2344490 TELECOMMUNICATIONS NETWORKS

FIELD OF THE INVENTION

The present invention relates to telecommunications networks, and in particular to methods and apparatus for allowing roaming between separate telecommunications networks.

DESCRIPTION OF THE RELATED ART

With the ever increasing number of mobile telephone subscribers, and increasing numbers of telecommunications networks being set up to provide services for those subscribers, it is becoming is important to enable subscribers to move, or roam, between different networks. One example of such a situation is in China where the mobile telecommunications networks are provided by a number of different operators each of which provides a provincial mobile telephone network. Roaming agreements exist between the provincial networks to allow roaming of subscribers between the networks.

However, this non-homogenous network structure (i.e. a group of separately provided networks) means that it is very difficult to provide added service functions to subscribers across the whole country, since each region is serviced by a varying range of hardware and software. One particular example is the pre-paid service in which subscribers pay up-front for their use of the telecommunications network. with such pre-paid services it is necessary to provide real time call duration supervision and so providing full roaming service can be difficult. In a homogenous network this function can be provided by all of the switching centres. However, in a non-homogenous network where the majority of switching centres are not able to provide pre-paid services, a subscriber making use of pre-paid services will not be able to use those services when roaming to such a visiting mobile switching centre. Generally, the subscriber is barred from making or receiving calls in such an area.

SUMMARY---OF THEPRESENT INVENTIO

It is the intention of the present invention to provide methods and apparatus which enable pre-paid service subscribers to roam freely, even to networks not providing the pre-paid services.

According to one aspect of the present invention there is provided a method of handling a call request from a mobile subscriber roaming to a telecommunications network, the mobile subscriber is having a home network which supports pre-paid services, the method comprising:

receiving a call request from the roaming subscriber; obtaining subscriber information relating to the roaming subscriber, which subscriber information includes an indication as to whether the roaming subscriber uses pre-paid services; and if the subscriber information indicates that the roaming subscriber uses pre-paid services, routing the requested call via a pre-paid switching centre in the home network.

According to another aspect of the present invention, there is provided a method of handling a call request from a mobile subscriber roaming to a telecommunications network from the subscriber's home network, the method comprising:

receiving a subscriber information request from the'telecommunications network; returning subscriber information to the telecommunications network, the information including an indication as to whether the subscriber uses pre- paid services; and if the subscriber uses pre-paid services, receiving and routing the call from the telecommunications network through a pre-paid switching centre in the home network.

According to another aspect of the present invention, there is provided a telecommunications network comprising switching centre means for receiving a call request from a subscriber having a home network and roaming to the telecommunications network, the switching centre means being operable to obtain subscriber information relating to the roaming subscriber, and, if the subscriber information indicates that the subscriber uses pre-paid services, is to route the requested call via a pre-paid switching centre in the home network of the roaming subscriber.

According to another aspect of the present invention, there is provided a node apparatus for a telecommunications network, the apparatus comprising:

request means for receiving a call request from a subscriber having a home network and roaming to the telecommunications network; information means for obtaining subscriber information relating to the roaming subscriber; and routing means operable to route the call via a pre-paid switching centre in the home network of the roaming subscriber, if the obtained subscriber information indicates that the roaming subscriber uses pre-paid services.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is schematic diagram illustrating mobile station roaming in conventional networks; I Figure 2 is schematic diagram illustrating-mobile station roaming in accordance with the present invention; Figure 3 illustrates a modified home location register (HLR) for use in the system of Figure 2; Figure 4 illustrates a modified VMSC for use in the system of Figure 2; Figure 5 is a block diagram illustrating a pre paid service switching centre of the system of Figure 2; Figure 6 is a flow chart illustrating steps in a method embodying the present invention for originating a call from a roaming mobile station; and Figure 7 is a flow chart illustrating steps in a method embodying another aspect of the present invention for routing a call to a roaming mobile station.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT is Figure 1 illustrates a mobile station 1 having a home network 2 roaming to a visited network 4. In the home network 2, a home location register (HLR) maintains subscriber information indicating the current location of the mobile station 1 and offer information relevant to the routing of calls to the subscriber.

Calls to and from the home network 2 are routed through a gateway mobile switching centre (GMSC) 8, via a communications link 10, in conventional fashion.

Mobile stations communicating with the network 2 communicate over respective air interfaces 9.

The roaming mobile station 1 communicates with a visiting mobile switching centre (VMSC) 12 in the visited network 4 via a link 13 which includes an air interface and one or more cell base stations (not shown), as is well known. The VMSC 12 communicates with the HLR 6 of the home network 2 by way of a communications link 11 in order to obtain information concerning the mobile station 1. The VMSC 12 routes calls from the mobile station 1 via a communication link 14.

As is well known, when the mobile station 1 wishes to make a telephone call whilst roaming to the visited network 4, it communicates with a VMSC 12 of that visited network. The VMSC 12 obtains roaming subscriber information from the HLR G and uses this information to route calls directly to the called party by way of link 14. The actual route for the call can be determined in a number of ways, for example the least cost route from the VMSC 12 to the destination, or the fastest route from the VMSC 12 to the destination.

However, such a system provides problems for roaming mobile stations 1 who have access to pre-paid services in the home network 2. The VMSC 12 will request subscriber information from the HLR 6, but is since the mobile station 1 is in a visited network 4 which does not support pre-paid services, the HLR 6 will instruct the VMSC 12 to reject the call.

Figure 2 illustrates telecommunications networks in accordance with the present invention. As before, the mobile station I whose home telecommunications network 2 includes and an HLR 6 and an GMSC 8, roams to another network 4 having a VMSC 12. The home network 2 further comprises a pre-paid gateway mobile switching centre (PPGMSC) 16, which can route calls to and from the network by way of a communications link 18. The PPGMSC 1G is in communication with the HLR 6. The VMSC 12 once again receives call request and communicates with the mobile station 1 by way of an air interface 13, and routes calls from the visited network 4 via a communications link 14.

As will be explained in more detail below,-when the mobile station 1 wishes to make a pre-paid services call, the VMSC 12 in the visited network 4 obtains from the HLR 6 subscriber information indicating that pre paid services are to be used, and that the call should be routed through the pre-paid gateway mobile switching centre 16 of the home network. The call is routed by the PPGMSC 16 to its destination by way of a communications link 18. Thus, pre-paid services can be provided to the mobile station 1 even when the visited network 4 does not itself support pre-paid services, since any pre-paid service call is routed via the PPGMSC 16 of the home network 2.

Some of the components shown in Figure 2 will now be described in more detail, followed by a more detailed description of the method embodying an aspect of the present invention.

Figure 3 is a block diagram illustrating a modified HLR 6 for use in a network operated in accordance with the present invention. The modified HLR 6 includes the usual functionality of a home location register for providing information regarding subscribers of that home network to, amongst others, visiting mobile switching centres (VMSC). The HLR 6 also includes VMSC message receive means 62 for receiving requests for subscriber information from a VMSC of another network. Such a message is decoded by the VMSC message decode means 63 which is used to determine what information the VMSC requires. An HLR message update means 64 retrieves information from a subscriber data base 65 and sends a message, via the TRX unit 61 to the requesting VMSC. In systems operating in accordance with the present invention, the HLR message includes information which indicates that the mobile station 1 is a pre-paid service user. This information is preferably in the form of preferred inter-exchange carrier (PIC) information The value of the PIC information uniquely identifies the pre-paid service provider (i.e. the home network) and therefore can be used by the VMSC to determine how to handle a call request from the mobile station 1.

Figure 4 is a block diagram illustrating a'VMSC for use in accordance with the present invention, which includes a transmit and receive (TX/RX) unit 121 for transferring data with mobile stations, home location registers and for routing calls. The VMSC 12 also includes call request receive means 122 for receiving and processing call requests received from visiting mobile stations which are roaming to the network 4.

The call request receive means 122 accesses a current subscriber data base 126 which holds subscriber information concerning mobile stations currently registered with the VMSC 12. The data base 126 obtains subscriber information from visiting mobile stations 1 own home location registers by way of HLR contact means which communicates with the relevant home location register (HLR) via the transmit and receive unit 121.

When a mobile station roams into the network 4, it registers with the VMSC 12, either in a specific registration step or when first making a call request.

When the mobile station registers with the VMSC, the subscriber information is obtained from the mobile stations HLR and stored in the database 126.

As mentioned above, in an embodiment of the present invention, the current subscriber information includes information indicating whether the subscriber has access to pre-paid services in the home network 2.

This is most usefully held in the form of preferred inter-exchange carrier (PIC) information. When a call request is received by the call request receive means 122, and the current subscriber information is retrieved from the data base 126, the call request receive means passes the PIC information to a PIC analysis means 123 of the VMSC 12. The analysis means 123 'determines whether the PIC information indicates that the requesting subscriber uses pre-paid services in the home network. If that is the case, then the result of the analysis is passed to CIC creation means 124 which produces a five digit carrier identification code (CIC) to indicate that pre-paid services are used in the home network. The CIC and dialled B number are then used for routing the call via the TX/RX unit 121.

Analysis of the CIC indicates to the VMSC 12 that the call must be routed to the PPGMSC 16 of the home network, and not over any other route.

Figure 5 is a block diagram illustrating a PPGMSC 16 for use in a network operated in accordance with the present invention. The PPGMSC 16 includes a transmit/receive unit TX/RX 161 for communicating with the HLR 6, the VMSC 12 and for routing calls via the communication links 17 and 18. When a call request is received from a VMSC of a visited network, the call request including a carrier identification code (CIC) and the dialled B number, as well as an indication of the calling subscriber, this information is passed to subscriber verification means 162 which accesses a subscriber database 167 in order to determine whether the subscriber concerned has sufficient credit to enable the call to be set up. Assuming this to be the case, then the call request information is passed to CIC removal means 163 which removes the carrier identification code from the dialled B number so' that the B number can be passed to analysis means 164 to determine the calls destination, and from there to routing means 165 for routing the call from the PPGMSC to the called party in the usual way.

Such a system enables the PPGMSC 16 to be linked into the call path, since the VMSC 12 is forced to route all calls from the pre-paid subscriber via the PPGMSC 16 in the home network 2, and so the PPGMSC 16 can 'provide the pre-paid services required for the roaming mobile station 1. Pre-paid service means 166 provide the pre-paid services, and in particular can provide call duration supervision in order to update the subscriber data base with regard to credit remaining after a call.

In the case when the roaming subscriber is the subject of a call, the subscriber's HLR is queried to obtain the location of the subscriber. In addition, if the subscriber is a pre-paid subscriber then the HLR indicates that the call must be routed via the PPGMSC 16 of the home network 2 so that call duration supervision can be performed.

Reference will now be made to Figure 6 which is a flow chart indicating steps in accordance with the present invention in which a roaming mobile station using pre-paid services originates a call in a visited network. At step 6a the mobile station originates the call. The VMSC then retrieves subscriber information, either direct from the HLR of the requesting station or from the subscriber database (DB). As previously described, the subscriber information includes preferred interexchange carrier (PIC) information which identifies the pre-paid service provider and effectively indicates that the requesting subscriber uses pre-paid services. This PIC information is stored (step 6c). The PIC information is then checked (step Gd) and the VMSC determines if pre-paid services are used by the subscriber (step 6e).

If pre-paid services are not used, then the. normal call service is provided for that subscriber (step f), but if pre-paid services are used, then a carrier identification code (CIC), indicating the PPGMSC 16 to be used is added to the called number (B number) (step g). The VMSC then uses the CIC information to route the call to the correct PPGMSC (step h).

The PPGMSC ascertains whether the pre-paid subscriber is in credit (step i), and if not the call is rejected (step j). If the subscriber does have sufficient credit, then the CIC is removed (step M, and the called B number used to set up the call (step 1). As described, this means that the call f rom the subscriber is always routed through the PPGMSC. The PPGMSC can then monitor call duration and other call characteristics (step m).

With reference to Figure 7, in order to route a call to a subscriber, the network GMSC receives a call request (step 7a) from the caller. The subscriber information relating to the intended called party is checked (step 7b) in order to determine whether pre paid services are used by the intended called party (step 7c). If pre-paid services are used, then the call is routed via the PPGMSC (step 7d) in order that the call can be monitored. If the intended call party does not use pre-paid services, then normal call service is provided for that call (step 7e).

The main benefit of embodiment of the present invention is that it is possible to provide full pre paid roaming to exchanges that are not specifically adapted for pre-paid service provision. Although the systems in use in China are TACS networks (total access communication system networks) providing analogue telecommunications networks, the embodiments of the invention rely on the use of the preferred interexchange carrier (PIC) and carrier identification code (CIC) information used in combination to enable calls from pre-paid subscribers to be monitored by the home network PPGMSC. In addition, the techniques can be applied to provide access to a new pre-paid node introduced into any current telecommunication standard that supports the use of PIC and CIC. For example, it is possible to facilitate international pre-paid roaming in GSM or AMPS networks using such a technique.

Embodiments of the invention can achieve these advantages by providing a pre-paid switching centre in the home network of the pre-paid service, and ensuring I that networks route pre-paid calls via that pre-paid switching centre, and not by any other route. Thus by using this solution, an operator in one region or network can offer its subscribers a pre-paid service irrespective of the operating capabilities of other VMSCs which will enable pre-paid subscribers to roam throughout a number of networks. The only other requirement which is needed to provide this functionality is for the operators of the other networks to define correctly the B number analysis tables and to provide PIC and CIC translation tables to route calls to the PPGMSC when the PIC and CIC information indicates that this is to be the case.

However, such a change is relatively minor since telecommunications networks which support the use of PIC and CIC need merely to add additional translations of the particular PIC and CIC codes relating to the PPGMSC.

Claims

CLAIMS:

1 - A method of handling a call request from a mobile subscriber operating in a telecommunications network, the mobile subscriber having a home network which supports pre-paid services, the method comprising:

receiving a call request from the subscriber; obtaining subscriber information relating to the subscriber, which subscriber information includes an indication as to whether the subscriber uses pre-paid services; and if the subscriber information indicates that the subscriber uses pre-paid services, routing the requested call via a dedicated pre-paid switching centre.

2. A method as claimed in claim 1, wherein the pre-paid switching centre is in the home network.

3. A method as claimed in claim 1 or 2, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which is used to indicate that the subscriber uses pre-paid services.

4. A method as claimed in claim 1, 2 or 3, wherein the requested call is routed to the pre-paid switching centre on the basis of carrier identification code (CIC) information.

S. A method as claimed in any one of claims 1 to 4, wherein the subscriber information is obtained from the home network of the subscriber in response to reception of the call request from the subscriber.

6. A method as claimed in any one of claims 1 to 4, wherein the subscriber information is obtained from the home network of the subscriber in response to registration by the subscriber, the information being stored for use in handling a call request from the subscriber.

7. A method as claimed in claim 1, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which indicates whether the subscriber uses pre-paid services, and wherein, if the subscriber information indicates that the subscriber uses prepaid services, the method comprises generating carrier identification code (CIC) information indicating that the call should be routed through the pre-paid switching centre, and supplying the CIC information and called party number (B-number) to the home network for call routing.

8. A method of handling a call request from a mobile subscriber operating in a telecommunications network, the subscriber having a home network, the method comprising:

receiving a subscriber information request from the telecommunications network; returning subscriber information to the telecommunications network, the information including an indication as to whether the subscriber uses pre paid services; and if the subscriber uses pre-paid services, receiving and routing the call from the telecommunications network through a pre-paid switching centre.

9. A method as claimed in claim 8, wherein the pre-paid switching centre is in the home network of a subscriber.

10. A method as claimed in claim 8 or 9, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which is used to indicate that the subscriber uses pre-paid services.

11. A method as claimed in claim 8, 9 or 10, wherein the requested call is routed to the pre-paid switching centre on the basis of carrier identification code (CIC) information.

12. A method as claimed in any one of claims 8 to 11, wherein the subscriber information is returned in response to reception of the call request from the subscriber.

13. A method as claimed in any one of claims 8 to 11, wherein the subscriber information is returned in response to registration by the subscriber.

14. A method as claimed in claim 8, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which indicates whether the subscriber uses pre-paid services, and wherein, if the subscriber information indicates that the subscriber uses prepaid services, the method comprises receiving carrier identitication code (CIC) information and called party number (B-number) for use in routing the requested call.

15. A telecommunications network comprising switching centre means for receiving a call request from a subscriber having a home network and operating in the telecommunications network, the switching centre means being operable to obtain subscriber information relating to the subscriber, and, if the subscriber information indicates that the subscriber uses pre-paid services, to route the requested call via a pre-paid switching centre.

16. A network as claimed in claim 15, wherein the pre-paid switching centre is in the home network of the subscriber.

17. A network as claimed in claim 15 or 16, wherein the subscriber information includes preferred inter-exchange carrier (PIC) information which is used to indicate that the subscriber uses pre-paid services.

18. A network as claimed in claim 15, 16 or 17, wherein the requested call is routed to the pre-paid switching centre on the basis of carrier identification code (CIC) information.

19. A network as claimed in any one of claims 15 to 18, wherein the switching centre means is operable to obtain subscriber information from the home network of the subscriber in response to reception of the call request from the subscriber.

20. A network as claimed in any one of claims 15 to 18, wherein the switching centre means is operable to obtain subscriber information from the home network of the subscriber in response to registration by the subscriber, the information being stored for use in handling a call request from the subscriber.

21. A network as claimed in claim 15, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which indicates whether the subscriber uses pre-paid services, and wherein, if the subscriber information indicates that the subscriber uses prepaid services, the switching centre means includes means for generating carrier identification code (CIC) information indicating that the call should be routed through the pre-paid switching centre, and means for supplying the CIC information and called party number (B-number) for call routing.

22. Node apparatus for a telecommunications network, the apparatus comprising:

request means for receiving a call request from a subscriber having a home network and operating in the telecommunications network; information means for obtaining subscriber information relating to the subscriber; and routing means operable to route the call via a pre-paid switching centre, if the obtained subscriber information indicates that the subscriber uses pre-paid services.

23. Apparatus as claimed in claim 22, wherein the pre-paid switching centre is in the home network.

24. Apparatus as claimed in claim 22 or 23, wherein the subscriber information includes preferred inter-exchange carrier (PIC) information which is used to indicate that the subscriber uses pre-paid services.

25. Apparatus as claimed in claim 22,23 or 24, wherein the requested call is routed to the pre-paid switching centre in the home network on the basis of carrier identification code (CIC) information.

26. Apparatus as claimed in any one of claims 22 to 25, wherein the information means is operable to obtain subscriber information from the home network of the subscriber in response to reception of the call request from the subscriber.

27. Apparatus as claimed in claims 22 to 25, wherein the information means is operable to obtain subscriber information from the home network of the subscriber in response to registration by the subscriber, the information being stored for use in handling a call request from the subscriber.

28. Apparatus as claimed in claim 22, wherein the subscriber information includes preferred inter exchange carrier (PIC) information which indicates whether the subscriber uses pre-paid services, and wherein, if the subscriber information indicates that the subscriber uses prepaid services, the apparatus includes means for generating carrier identification code (CIC) information indicating that the call should be routed through the pre-paid switching centre, and means for supplying the CIC information and called party number (B-number) for call routing.

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