SYSTEM AND METHOD FOR DETECTING UNAUTHORIZED USE OF A CELLULAR TELEPHONE

Abstract: A system and method for detecting and preventing cellular fraud in a cellular network. The network includes a database such as a home location register that stores a listing of potential terminating numbers that the authorized user is allowed to call. Therefore, whenever a call is initiated by a cellular telephone using the identification number of the authorized user, the called number is compared to the listing. If the called number is in the listing, the call completes normally. If not, an additional level of security can be provided. For example, the caller may be prompted for a security code, the caller may be transferred to a service center, or the caller may be transferred to a cellular-fraud-prevention task force. If, in the first example, the caller supplies the correct security code, then it is assumed that he is the authorized user and the call completes normally. Furthermore, the called number may then be added to the listing. Otherwise, it is assumed that the caller is a fraudulent user and is handled accordingly.

Description: SYSTEM AND METHOD FOR DETECTING UNAUTHORIZED USE OF A CELLULAR TELEPHONE Technical Field This invention relates generally to wireless communication networks, and in particular, to a system and method for detecting and preventing an unauthorized cellular telephone user from fraudulently using account information of another to complete a call. Background The cellular communications industry has experienced very rapid growth in both the areas serviced and the number of subscribers. It is not uncommon in many metropolitan areas for mobile switching centers (MSCs) to have service requests numbering in excess of 100,000 call attempts per hour. In these metropolitan areas, each MSC may serve a network of 100 or more cell sites, or base stations, each of which defining a particular cell. In cellular communication networks, a mobile unit such as a cellular telephone subscribes to a group of MSCs, hereinafter represented by a single "home" MSC. The home MSC maintains a home location register ("HLR") database containing a profile for the mobile user, including information such as subscribed features (e.g., call waiting or call forwarding) and current status (e.g., active or inactive). By using the HLR, the mobile unit may roam, or visit, in areas served by different MSCs that have access to the HLR, thereby having access to the user's profile information. Each MSC also keeps track of visiting mobile units currently operating in its service area via a visitor location register (VLR) database. The VLR contains information regarding the services available to each subscriber, his home MSC and HLR, and the current status of the mobile unit. When a call is initiated from an external network to a mobile unit believed to be within the service area, a page must be broadcast over a forward control channel to all cells in the service area. The mobile unit responds to the page by providing a unique mobile identification number ("MIN") and electronic serial number ("ESN") that identify the mobile unit. When the mobile unit responds to the page, the particular cell containing the mobile unit is then identified from a reverse control channel used for the mobile response and a cellular link is then set up. If the MSC providing service for the call (the "serving" MSC) recognizes the MIN and ESN, as well as other certain parameters, a cellular link is established with the mobile unit and the call is completed to the destination number. As cellular phone usage has increased, cellular fraud has become more and more prevalent. Cellular fraud occurs when an unauthorized cellular device uses the MIN and ESN associated with a legitimate mobile unit. Once the MIN and ESN have been discovered, the unauthorized cellular device may utilize the cellular communication network at the expense of the legitimate mobile unit. Furthermore, due to the very nature of mobile units, it is extremely difficult to track down the unauthorized device. One solution to prevent cellular fraud is to require a personal identification number ("PIN") to be included with each call. However, this solution is often ineffective because the PIN can be stolen as easily as the MIN and ESN. Summary The foregoing problems are solved and a technical advance is achieved by a system and method for detecting and preventing cellular fraud. In one embodiment, a database such as a home location register stores a listing of potential terminating numbers that the authorized user may call. Therefore, whenever a call is initiated by a cellular telephone using the identification numbers of the authorized user, the called number is compared to the listing. If the called number is in the listing, the call completes normally. If not, an additional level of security can be provided. For example, the caller may be prompted for a secxirity code, the caller may be transferred to a service center, or the caller may be transferred to a cellular-fraud-prevention task force. If, in the first example, the caller supplies the correct security code, then it is assumed that he is the authorized user and the call completes normally. Furthermore, the called number may then be added to the listing. Otherwise, it is assumed that the caller is a fraudulent user and is handled accordingly. An advantage with the present invention is that it adapts easily and inexpensively to existing cellular telephones and switches. Another advantage with the present invention is that since the security code is seldom used, it is difficult to steal. Brief Description of the Drawings Fig. 1 illustrates an exemplary cellular communication network. Fig. 2 is a flowchart illustrating a method for detecting and preventing cellular fraud, such as may occur in the cellular communication network of Fig. 1. Description of the Preferred Embodiment Referring to Fig. 1, the reference numeral 10 designates a simplified communication network. The communication network 10 includes a first cellular network 12, a second cellular network 14 and a public switched telephone network ("PSTN") 15. The first cellular network 12 is graphically represented by an MSC 16 and two cell sites 18 and 20. The MSC 16 serves to interconnect the PSTN 15 with a cellular telephone 22 through the cell site 18. Likewise, the second cellular network 14 is graphically represented by an MSC 26 and two cell sites 28 and 30. The MSC 26 serves to interconnect the PSTN 15 with a cellular telephone 32 through the cell site 28. The PSTN 15 is also connected to two land-line telephones 34 and 36 and an interactive voice response system ("INR") 38. Associated with each of the MSCs 16, 26 are internal processing and storage devices (not shown) and NLRs 16a, 26a, respectively. It is understood that although the cellular networks 12 and 14 are shown as separate and distinct, they may alternatively represent subsets of a single, larger cellular network. Since both of the switches 16, 26, are physically connected to the PSTN 21, calls may be completed between any combination of the telephones 22, 32, 34 and 36. The MSCs 16, 26, as well as the INR 38, are also connected to an intelligent network ("IN") 40. The IN 40 includes a conventional signaling protocol such as Signaling System 7 and is capable of accessing data from a signal control point ("SCP") database 42 and an HLR 44 associated with the MSC 16. The IN 40 may be used for various conventional purposes, including facilitating roaming of the cellular telephone 22 between the two cellular networks 12 and 14. Referring to Fig. 2, a routine 100 is used to prevent cellular fraud by an unauthorized cellular telephone. For the sake of example, the routine will be applied to the communications network 10 of Fig. 1. In this example, the cellular telephone 22 is an authorized user with a valid MIN and ESN and a subscriber to the MSC 16 while the cellular telephone 32 has obtained the MIN and ESN of the cellular telephone 22 and is attempting use thereof. At step 102, the authorized user (cellular telephone 22) defines a listing of potential phone numbers that he is allowed to call. Tables 1 and 2 below give examples of such listings. The first column CDNIDX of each table provides index values with which the individual rows, or records, of may be identified. For each authorized user, one or more indices may be used to determine which terminating telephone numbers have been pre- allowed. The second column RGE of each table indicates whether a range of numbers (Table 1) has been pre-allowed or individual numbers (Table 2) have been pre-allowed. Referring to Table 1, the third and fourth columns, FROMDIGS and TODIGS, provide the range of potential terminating telephone numbers for domestic calls. The fifth column INTL is an indicator of whether international calls are allowed. The sixth and seventh columns, FRO and TO, provide a range of potential terminating telephone numbers for international numbers. Referring to Table 2, the third, fourth and fifth columns, NUM1, NUM2 and NUM3, indicate individual potential terminating telephone numbers. The number of columns in Table 2 is dynamic, being determined by the number of pre-allowed potential terminating telephone numbers. Table 1 Table 2 In addition, the authorized user may establish personalized information that may be used to denote authorization. For example, the personalized information may be security code, a mother's maiden name or some other password. The information of Tables 1 and 2, along with the personalized information, may be stored in several different places. For one, it may be stored in a database (HLR 44) associated with the user's home network (cellular network 12). Alternatively or in addition, the information may be stored in a database (SCP 42) connected to the serving switch (MSC 26) through an intelligent network (IN 40). In continuance of the present example, the authorized user (cellular telephone 22) has established the listing as indicated by CDNIDX index 3. The phone number for the land-line telephone 34 is 7135551111 and is included in the range of potential terminating telephone numbers associated with CDNIDX index 3. The phone number for the land-line telephone 36 is 2145551111 and is not included in the range of potential terminating telephone numbers associated with CDNIDX index 3. At step 104, a caller (cellular telephone 32) initiates a call to a destination phone (telephone 34 or 36) by contacting the serving switch (MSC 26). At step 106, the serving switch (MSC 26) accesses the listing of potential terminating telephone numbers that was established at step 102 (Tables 1 and 2). The serving switch may automatically access the listings, or may be triggered by a certain code stored along with the caller's general profile information. In one embodiment, the serving switch can access the listing by querying (using CDNIDX index 3) a database (HLR 44) and copying the retrieved information (the potential terminating telephone numbers associated with the CDNIDX index 3) into one of its own databases (VLR 26a). In this way, the data is available for subsequent calls without requiring additional queries to the external database. In another embodiment, the serving switch (MSC 26) can access the listing by querying another database (SCP 42) attached to the switch through an intelligent network (IN 40). In a third embodiment, the listing may presently exist in the serving switch. Using the third embodiment, the routine 100 may be tested and implemented in a single switch. At step 108 a determination is made as to whether the initiated call is authorized. (Is it is to one of the potential terminating telephone numbers associated with CDNIDX index 3?) If so (telephone 34), execution proceeds to step 110 where the call is completed. If not (telephone 36), execution proceeds to step 112 and the call is directed to a service provider (INR 38). At step 114, a determination is made as to whether the caller is an authorized user. There are several methods for determining if the caller is authorized. For one, the caller may be prompted (by the INR 38) for a security code, his response being compared to the security code stored during step 102. Alternatively, the caller may be transferred to a service center that asks questions such as the caller's mother's maiden name. For another, the caller may be transferred to a cellular-fraud-prevention task force who then takes steps to track down the caller. If the caller is authorized, execution proceeds to step 110 where the call is completed. In addition, the service provider (INR 38) may also add the called number (telephone 36) to the list of potential terminating telephone numbers. If the caller is not authorized, the call is not completed. Instead execution proceeds to step 116 where the unauthorized caller is appropriately handled. Although illustrative embodiments of the invention have been shown and described, other modifications, changes, and substitutions are intended in the foregoing disclosure. For example, the above system and method can be used in many different types of wireless networks and the switches can be of many different types. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims: WHAT IS CLAIMED IS: 1. A method for regulating the use of a wireless network, the method comprising the steps of: receiving an identification signal identifying a potential user and a destination signal identifying a potential destination location; accessing one or more records of predetermined destination locations associated with the identified potential user to determine if the potential destination location is included therewith; if the potential destination location is included in the one or more records, connecting the identified potential user to the potential destination location. 2. The method of claim 1 further comprising the step of: preventing the identified potential user from connecting to the potential destination location if the potential destination location is not included in the one or more records. 3. The method of claim 1 further comprising the steps of: prompting the identified potential user for a code if the potential destination location is not included in the one or more records; and connecting the identified potential user to the potential destination location in response to receipt of the code. 4. The method of claim 3 further comprising the step of: prohibiting the identified potential user from connecting to the potential destination location if the potential destination location is not included in the one or more records and the code is not received. 5. The method of claim 3 further comprising the step of: adding the potential destination location to the one or more records. 6. The method of claim 1 wherein the wireless network is a cellular telephone network. 7. The method of claim 1 wherein the signals are received by a switch and the step of accessing includes querying a database for the one or more records. 8. The method of claim 7 wherein the database is stored in the switch. 9. The method of claim 7 wherein the database is accessible via a network connected to the switch. 10. The method of claim 7 wherein the one or more records are first copied to the switch. 11. The method of claim 7 wherein the one or more records define general areas of potential destination locations. 12. A system for determining whether a mobile unit is a fraudulent user of a cellular communication network, the system comprising: a storage device for storing a listing of potential terminating numbers; a receiver for receiving a call including an identification number from the mobile unit and a desired terminating number; a processing device for querying the listing of potential terminating numbers associated with the identification number, to determine if the desired terminating number is authorized; and a switch for connecting the mobile unit to the destination location if the desired terminating number is authorized; wherein the listing of potential terminating numbers was established by the user before the call was received. 13. A system for regulating the use of a wireless network by a caller, the system comprising: a receiver for receiving an identification number identifying a user and a destination number identifying a destination location; processing means for accessing a database to determine if connection to the destination location has been pre-allowed by an authorized user; means for connecting the caller to the destination location if it is determined that the connection has been pre-allowed. 14. The system of claim 13 wherein the means for connecting will not connect the caller to the destination location if the connection has not been pre-allowed by the user. 15. The system of claim 13 further comprising: a service provider for prompting the user for a code if the connection has not been pre-allowed by the user; wherein the means for connecting connects the caller to the destination location in response to receipt of the code. 16. The system of claim 15 wherein the means for connecting will not connect the caller to the destination location if the connection has not been pre-allowed by the user. 17. The system of claim 15 wherein the processing means adds the destination location to the database upon receipt of the code. 18. The system of claim 13 wherein the wireless network is a cellular telephone network and the user is a cellular telephone. 19. The system of claim 13 wherein the numbers are received by a switch and the processing device is connected to the switch. 20. The system of claim 19 wherein the database is stored in the switch. 21. The system of claim 19 wherein the database is accessible via a network. 22. The system of claim 19 wherein the database is first copied to the switch. 23. The system of claim 19 wherein the database includes a listing of destination locations designated in advance by the user. 24. The system of claim 23 wherein the switch includes an index for identifying certain records of the pre-allowed destination locations.

Inventors: THURLEY RICHARD N, THURLEY, RICHARD, N.
Applicants: NORTHERN TELECOM LTD, NORTHERN TELECOM LIMITED
Application year: 1998
Main classification: H04Q7
IPC codes: H04W12