WO2008017951A2

WO2008017951A2 - Making a call by a prepaid subscriber roaming in a visited non-camel network

Info

Publication number: WO2008017951A2
Application number: PCT/IB2007/002327
Authority: WO
Inventors: Mustafa A. Kazmi
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2006-08-11
Filing date: 2007-08-10
Publication date: 2008-02-14
Also published as: WO2008017951A3

Abstract

A SIM (201) within mobile device or terminal (202) is programmed with the list of Mobile Switching Centers (MSC) /Visitor Location Registers (VLRs) that cannot support CAMEL. The SIM (201) is programmed with a USSD (Unstructured Supplementary Service Data) Code (e.g. *BAL#) which is used for obtaining a balance inquiry from a prepaid system (205). When the subscriber is visiting in a non-CAMEL MSC (203), a SIM application (201A) loaded in the SIM (201) launches the USSD balance inquiry (e.g. *BAL#) while the call set up is on-going. The mobile device or terminal (202) communicates via the subscriber's HLR (204) to the prepaid system (203), then returns the balance. This is an existing feature in many prepaid systems. The SIM application (201A) authorizes the call if the balance is above a certain threshold. As an extension, the SIM application (201A) can launch the USSD balance inquiry during the call at a regular intervals and let the call continue if the balance is sufficient. If the balance goes below a threshold, the mobile device or terminal (202) through SIM application (201A) will tear down the call.

Description

APPARATUS AND METHOD FOR MAKING A CALL BY A PREPAID SUBSCRIBER IN A NON-CAMEL NETWORK

CROSS-REFERENCE TO RELATED APPLICATIONS

NOT APPLICABLE

BACKGROUND OF THE INVENTION

The present invention relates to mobile cellular telecommunication networks. More particularly, and not by way of limitation, the present invention is directed to an improved system and method for making calls by a prepaid subscriber using the Unstructured Supplementary Service Data (USSD) of a Subscriber Identity Module (SIM) card.

The Customized Applications for Mobile network Enhanced Logic (CAMEL) provides mechanisms to support services of operators, which are not covered by standardized GSM services even when roaming outside the Home Public Land Mobile Network (HPLMN).

CAMEL is a network tool that assists a network operator in providing subscribers with operator specific services even when roaming outside the HPLMN. In the specification, the GSM Service Control Function (gsmSCF) is treated as being part of the HPLMN. However, the regulatory environment in some countries requires that the gsmSCF and the HPLMN be controlled by different operators, such that the gsmSCF and the HPLMN are distinct entities.

The CAMEL mechanism addresses especially the need for information exchange between the Visited PLMN (VPLMN) or Interrogating PLMN (IPLMN) and the HPLMN for support of operator specific services. Subscribers who have subscribed to operator specific services and therefore need the functional support of the CAMEL feature are marked in the HPLMN and VPLMN. In case a subscriber is marked to need CAMEL support, the appropriate procedures, which provide the necessary information to the VPLMN or to the HPLMN, are invoked. It is possible for the HPLMN to instruct the VPLMN or IPLMN to interact with a gsmSCF, which is controlled by the HPLMN. GSM Mobile Application Part (MAP) is an evolution of the USSD mechanism used by prepaid vendors. The MAP protocol typically runs on top of the Signaling System 7 (SS7) protocol. MAP is a non call-associated signaling protocol. It provides the support for interactive mobile applications (cellular, paging, voice messaging, etc.) in a distributed environment. MAP defines the end-to-end protocol between applications which may be located in an SS7 network, and/or other networks supporting the MAP protocol.

The MAP protocol provides mechanisms to communicate between a

Mobile Switching Center (MSC) and Visitor Location Register (VLR) ("B" interface), MSC and Home Location Register (HLR) ("C" interface), Visitor

Location Register (VLR) and HLR ("D" Interface), VLR and VLR ("G" Interface),

MSC and MSC ("E" interface), MSC and Short Message Service gateway

(SMS) ("H" interface) and MSC and Equipment Identification Register (EIR) ("F" interface). The MAP protocol is encoded in ASN.1 Basic Encoding rules (BER) as a part of the SS7 stack above the TCAP protocol.

Today some prepaid vendors offer a feature called "USSD Call Back for Non-CAMEL Roaming". The feature works as shown in Figure 1.

As seen in Figure 1 , when a prepaid subscriber wants to roam in a network 101 that does not support CAMEL, he inputs a long USSD string (e.g. *CAL#) 1234567890# where 1234567890 is the number to be called. The visited network 101 communicates with the Home Location Register (HLR) 102 of the subscriber's home network 103. The HLR 102 contacts the prepaid system 104. The prepaid system 104 directs the home network 103 to set up two call legs, one to the calling party and the other to the called party. The mobile device of each party rings. Each party can then answer their respective mobile device and commence communication. The prepaid system 104 monitors the call for duration and charges the subscribers accordingly.

Disadvantageously, the calling subscriber must wait for a ringing tone after pressing the long string. This presents an unusual user experience as the caller is making a call and not prepared to hear his/her mobile device ringing.

One method to overcome the disadvantage, but which has its own disadvantages, is to allow the caller to make the call as if he/she were a postpaid subscriber. Later, the HPLMN collects the Call Detail Records (CDRs) from the visited Public Land Mobile Network (PLMN) and charge him/her retroactively.

It would be advantageous to have a system and method for that is adapted to use a SIM card to permit a prepaid caller to make a call in a non- CAMEL network and, hence, overcome the disadvantages of the prior art. The present invention provides such a system and method.

BRIEF SUMMARY OF THE INVENTION

The present invention is an improved system and method that uses information from a SIM card to permit a prepaid caller to make a call in a non-

CAMEL network. The system and method of the present invention is preferably part of a hosted prepaid system and utilizes part of the GSM MAP standard and a USSD balance inquiry feature.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the following section, the invention will be described with reference to exemplary embodiments illustrated in the figures, in which:

FIG. 1 is an illustration of the conventional method of permitting a prepaid subscriber to make a call in a non-CAMEL network; and FIG. 2 is an illustration of an embodiment of the present invention in which a prepaid subscriber is able to make a call in a non-CAMEL network.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an improved system and method that uses information from a SIM card of a mobile device or terminal to permit a prepaid caller to make a call in a non-CAMEL network. The system and method of the present invention is preferably part of a hosted prepaid system and utilizes part of the GSM MAP standard and a USSD balance inquiry feature.

The method of the present invention is implemented in a SIM card as seen in Figure 2 as follows:

1. A SIM 201 within mobile device or terminal 202 is programmed with the list of Mobile Switching Centers (MSC)/Visitor Location Registers (VLRs) that cannot support CAMEL. -A -

2. The SIM 201 is programmed with a USSD Code (e.g. *BAL#) which is used for obtaining a balance inquiry from a prepaid system 205.

3. When the subscriber is visiting in a non-CAMEL MSCs 203, a SIM application 201A loaded in SIM 201 launches the USSD balance inquiry (e.g. *BAL#) while the call set up is on-going.

4. The mobile device or terminal 202 communicates via the subscriber's home HLR 204 to prepaid system 203 then returns the balance. This is an existing feature in many prepaid systems.

5. The SIM application 201A authorizes the call if the balance is above a certain threshold.

6. As an extension, the SIM application 201A can launch the USSD balance inquiry during the call at a regular interval and let the call continue if the balance is sufficient.

7. If the balance goes below a threshold, the mobile device or terminal 202 through SIM application 201 A will tear down the call.

By using the above disclosed embodiment of the present invention, the subscriber is able to make a normal call using a mobile device or terminal. The user experience for making a call is the same, regardless of the network in which the user is roaming. The present invention also concerns apparatus, controllers and computer programs for executing the above method. The apparatus and controllers can be adapted to perform the method as described above. The present invention also concerns computer programs, each of the computer programs being loadable from a SIM into a processing unit of a corresponding terminal. The computer programs comprise portions of software codes in order to implement the method as described above when operated by the corresponding terminal. The computer programs can also be stored on computer readable media. A computer-readable medium can be a permanent or rewritable memory within a device or located externally. The computer programs can be also transferred to the devices for example via a cable or a wireless link as a sequence of signals.

As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed above, but is instead defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of using a mobile device or terminal (202) in a non- Customized Applications for Mobile network Enhanced Logic (CAMEL) network

(203), characterized by the steps of: programming a Subscriber Identity Module (SIM) card (201) of the mobile device or terminal (202) with a list of Mobile Switching Centers (MSC)/Visitor Location Registers (VLRs) that cannot support CAMEL; and programming the SIM card (201) with an Unstructured Supplementary

Service Data (USSD) code which is used for obtaining a USSD balance inquiry from a prepaid system (205).

2. The method of claim 1 , further characterized by the steps of: identifying when a terminal (202) is visiting in a non-CAMEL MSC; loading a SIM application (201A) that launches the USSD code for obtaining the balance inquiry from the prepaid system (205) via a Home Location Register (HLR) (204) while the call set up is on-going.

3. The method of claim 2, further characterized by the step of returning a balance inquiry value from the prepaid system (205).

4. The method of claim 3, further characterized by the step of authorizing the call if the balance inquiry value is above a certain threshold.

5. The method of claim 4, further characterized by the steps of: launching the USSD balance inquiry from the SIM application (201A) during the call at regular intervals; and allowing the call to continue if the balance is sufficient.

6. The method of claim 4, further characterized by the step of tearing down the call if the balance inquiry returns a value below a predetermined threshold.

7. A computer program on a computer readable medium adapted to be run on computer hardware adapted to the permit the use of a mobile device or terminal (202) in a non-Customized Applications for Mobile network Enhanced Logic (CAMEL) network (203), characterized by: a means for programming a Subscriber Identity Module (SIM) card (201) of the mobile device or terminal (202) with a list of Mobile Switching Centers (MSC)Λ/isitor Location Registers (VLRs) that cannot support CAMEL; and means for programming the SIM card (201) with an Unstructured Supplementary Service Data (USSD) code which is used for obtaining a USSD balance inquiry from a prepaid system (205) via a Home Location Register (HLR) (204).

8. The computer program of claim 7, further characterized by: means for identifying when a mobile device or terminal (202) is visiting in a non-CAMEL MSC; and means for loading a SIM application (201A) that launches the USSD code for obtaining the balance inquiry from the prepaid system (205) via the HLR (204) while the call set up is on-going.

9. The computer program of claim 8, further characterized by means of returning a balance from the prepaid system (205).

10. The computer program of claim 9, further characterized by means for authorizing the call if a balance obtained from the balance inquiry is above a certain threshold.

11. The computer program of claim 10, further characterized by: means for launching the USSD balance inquiry from the SIM application (201A) during the call at regular intervals; and means for allowing the call to continue if the balance is sufficient.

12. The computer program of claim 10, further characterized by means of tearing down the call if the balance inquiry returns a value below a predetermined threshold.

13. The computer program of claim 7, as implemented on a Subscriber Identity Module (SIM) card (201).

14. An apparatus adapted to the permit the use of a mobile device or terminal (202) in a non-Customized Applications for Mobile network Enhanced Logic (CAMEL) network, characterized by: means for programming a SIM card (201) of the mobile device or terminal (202) with a list of Mobile Switching Centers (MSC)Λ/isitor Location Registers (VLRs) that cannot support CAMEL; and means for programming the SIM card (201) with a Unstructured Supplementary Service Data (USSD) code which is used for obtaining a USSD balance inquiry from a prepaid system (205) via a Home Location Register (HLR) (204).

15. The appartus of claim 14, further characterized by: means for identifying when a mobile device or terminal (202) is visiting in a non-CAMEL MSC; and means for loading a SIM application (201A) that launches the USSD code for obtaining the balance inquiry from the prepaid system (205) via the

HLR (204) while the call set up is on-going.

16. The apparatus of claim 15, further characterized by means of returning a balance from the prepaid system (205) via the HLR (204).

17. The apparatus of claim 16, further characterized by means for authorizing the call if a balance obtained from the balance inquiry is above a certain threshold.

18. The apparatus of claim 17, further characterized by: means for launching the USSD balance inquiry from the SIM application (201A) during the call at regular intervals; and means for allowing the call to continue if the balance is sufficient.

19. The apparatus of claim 17, further characterized by means of tearing down the call if the balance inquiry returns a value below a predetermined threshold.

20. The apparatus of claim 13, as implemented in a mobile device or terminal (202).