Patent Publication Number: US-10311423-B2

Title: System and method for transaction approval based on confirmation of proximity of mobile subscriber device to a particular location

Description:
BACKGROUND OF THE INVENTION 
     It has become common practice for individual consumers to use credit cards for conducting transactions not only at conventional point-of-sale (POS) locations, but also for online transactions performed on the Internet. However, the convenience of credit card transactions is often negated by security measures commonly used to prevent fraudulent transactions, since transactions may be unexpectedly denied and additional action must be taken by the user to complete a transaction. 
     For instance, in POS credit and debit card transactions, a bank or other authorization entity associated with the credit or debit card (hereinafter referred to as “the card”) may deny any requested transactions that fall outside the normal pattern of use for that particular card, such as when the card is used for a transaction in a different city or state than the residence of the card user. When such transaction denials occur, the card user may be required to contact the authorization entity via a customer service phone number for transaction authorization, a procedure that can be time-consuming, frustrating, and, in cases where the user is engaged in foreign travel, quite expensive. 
     In online credit card transactions, particularly those exceeding a specified dollar amount, an authorization entity associated with the card may require two-factor authentication of the user before authorizing a requested transaction. For example, a personal identification number (PIN) or other alpha-numeric credential may be sent via text message to a mobile subscriber terminal, e.g., a mobile phone, that has been pre-registered as the mobile device of the card user. The user then enters the PIN to verify his or her identity to the authorization entity, which then authorizes the requested transaction. However, two-factor authentication using text messaging can be problematic, since text messaging adds cost to each transaction, is not always reliably received by a targeted mobile device in a timely manner, and not all mobile device users have text messaging plans. 
     Consequently, more convenient techniques have been used for two-factor authentication of both online and POS transactions. Specifically, the current location of a card user&#39;s mobile subscriber terminal has been used for two-factor authentication of card transactions; proximity of the card user&#39;s mobile subscriber terminal to the POS or the IP address associated with the transaction can indicate that the actual user of the card is requesting the transaction. Determination of the current location of the card user&#39;s mobile subscriber terminal can be a completely automated process, and therefore transparent to the card user, which is a significant benefit. Unfortunately, such two-factor authentication generally requires a card user&#39;s mobile subscriber terminal to continuously provide location information to the card&#39;s authorization entity, and in light of current concerns about electronic privacy, this requirement may be considered a serious drawback by many consumers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a block diagram of a transaction processing system and a point-of-sale (POS) financial transaction carried out according to an embodiment of the present invention. 
         FIG. 2  is a block diagram illustrating the steps of the POS financial transaction illustrated in  FIG. 1  as they occur sequentially along a time line, according to one or more embodiments of the invention. 
         FIG. 3  is a block diagram of a transaction processing system and an online transaction carried out according to an embodiment of the present invention. 
         FIG. 4  is a conceptual diagram illustrating a system that enables location tracking of mobile subscriber terminal in a home network, according to an embodiment of the present invention. 
         FIG. 5  schematically illustrates the contents of a location mapping database, according to an embodiment of the invention. 
         FIG. 6  is a conceptual diagram illustrating a system that enables location tracking of a mobile subscriber terminal roaming mode outside a home network, according to an embodiment of the present invention. 
         FIG. 7  schematically illustrates the contents of mapping database, according to an embodiment of the invention. 
         FIG. 8  is a flow chart that summarizes, in a stepwise fashion, a method for authenticating a user activity based on a location of a mobile communication device associated with a user without receiving location data for the device, according to an embodiment of the invention. 
     
    
    
     For clarity, identical reference numbers have been used, where applicable, to designate identical elements that are common between figures. It is contemplated that features of one embodiment may be incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of a transaction processing system  100  and a point-of-sale (POS) financial transaction carried out according to an embodiment of the present invention.  FIG. 2  is a block diagram illustrating the steps of the POS financial transaction illustrated in  FIG. 1  as the steps occur sequentially along a time line  190 , according to one or more embodiments of the invention. 
     As described below, transaction processing system  100  enables location-based authentication of a user activity even when a card user  101  has not consented to share location information directly with an authorization entity associated with a user&#39;s credit or debit card, e.g., a bank, credit union, or other financial entity. The user activity may be, for example, a debit or credit card transaction taking place at a conventional point-of-sale (POS) location, or a debit card transaction at an automated teller machine (ATM). In conjunction with another authentication factor, such as physical possession of the debit or credit card used in the transaction, transaction processing system  100  can facilitate two-factor authentication of the user activity. In other embodiments, transaction processing system  100  enables location-based authentication of whether an inquiring mobile communication device is within a certain distance (proximity threshold) from another mobile communication device. For example, a car service may want its drivers to confirm how many registered customers are within a certain distance from them. In another example, a dating service may want its registered users to confirm how many other registered customers who have compatible interests are within a certain distance from them. 
     Transaction processing system  100  may include a POS merchant  102 , an authorization entity  103 , a location verification entity  104 , and a location confirmation application  105 , the latter of which runs on a mobile subscriber terminal  110  associated with card user  101  and/or a credit or debit card. In the embodiment illustrated in  FIGS. 1 and 2 , multiple entities included in transaction processing system  100  each perform different actions of transaction processing system  100 . Specifically, authorization entity  103  determines the need for two-factor authentication and whether a debit or credit card transaction  121  is denied or authorized, location verification entity  104  determines if card user  101  is located proximate to POS merchant  102  by querying location confirmation application  105 , and location confirmation application  105  determines whether the current location of card user  101  is within a maximum allowable radius of POS merchant  102 . In such an embodiment, some or all of the communications described may be transmitted via one or more wireless and/or wired communication networks, such as the Internet, the Signaling System 7 (SS7) network, the Public Switched Telephone Network (PSTN) or a combination thereof. Such communications include an authorization request  122 , a location verification request  123 , a location query  124 , a location response  125 , a location verification  126 , a transaction authorization  127 , and a transaction denial  128 . In other embodiments, authorization entity  103  and location verification entity  104  may be configured as a single operational module, and some of the communications described herein may not be transmitted via an external communications network. 
     Transaction processing system  100  enables authorization entity  103  to approve user activity, such as a financial transaction with POS merchant  102 , based on location response  125  from mobile subscriber terminal  110 . Location response  125  is typically generated in response to a query (e.g., location query  124 ) from a location verification entity associated with the debit or credit card (e.g., location verification entity  104 ), and indicates whether or not the mobile subscriber terminal is within a specified maximum allowable radius of a specific location included in the query, i.e., the location of the user activity. It is noted that no specific location information for mobile subscriber terminal  110  is included in location response  125 . 
     POS merchant  102  may be a point-of-sale or so-called “brick and mortar” merchant that accepts payment using a debit or credit card associated with card user  101 . Authorization entity  103  may be any bank, credit union, financial institution, or other entity that can authorize transactions using the credit or debit card associated with card user  101 . Location verification entity  104  may be an application that runs on a server or other computing device coupled to the Internet or other communications network and is configured to perform a location verification operation as described herein. Location confirmation application  105  may be an application downloaded to and running on mobile subscriber terminal  110 , and may be configured as an authorization or software token that provides two-factor authentication of card user  101 . 
     Mobile subscriber terminal  110  may be a cellular telephone, a smart phone, a personal digital assistant (PDA), a tablet computer, or any other mobile computing device configured to wirelessly access the Internet or other communication network and to practice one or more embodiments of the present invention. Mobile subscriber terminal  110  may include a memory  111 , a processor  112 , and a wireless communication module  113 . Memory  111  may include any suitable volatile and/or nonvolatile memory (e.g., RAM, ROM, flash memory, a magnetic hard drive, etc.), and is configured to store instructions, data, location confirmation application  105 , and location information  114 . Processor  112  may be any suitable processing unit implemented as a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of processing unit, or a combination of different processing units, such as a CPU configured to operate in conjunction with a GPU. Wireless communication module may be any suitable electronics package and or chipset configured to enable wireless communication with any wireless network, including cellular networks, Bluetooth networks, and/or WiFi networks. 
     In operation, card user  101  initiates a credit or debit card transaction  121  at POS merchant  102  by presenting a credit or debit card. POS merchant  102  then submits an authorization request  122  to an authorization entity  103 , such as the issuing entity or bank of the credit or debit card. POS merchant  102  accepts the credit card as a form of payment for the purchase only when credit or debit card transaction  121  is authorized by authorization entity  103 . Thus, POS merchant  102  completes credit or debit card transaction  121  after receiving transaction authorization  127  from authorization entity  103 . According to embodiments of the invention, authorization entity  103  does not authorize credit or debit card transaction  121  unless a two-factor authentication process is successfully completed that includes verification that card user  101  is located within a maximum allowable radius of the location of POS merchant  102 . To that end, authorization request  122  includes location information for POS merchant  102  in addition to credit or debit card transaction information that is normally sent to authorization entity  103 , such as the name of card user  101  and an account number associated with the debit or credit card. 
     In some embodiments, when authorization entity  103  receives authorization request  122 , authorization entity  103  first determines whether a two-factor authentication process should be implemented, where the authentication process includes verification that card user  101  is located within the maximum allowable radius of the location of POS merchant  102 . Such two-factor authentication may be implemented when authorization request  122  is recognized to fall outside the normal pattern of use for the credit or debit card used for credit or debit card transaction  121 . For example, POS merchant  102  may be located outside a normal geographical region of use associated with the credit or debit card (e.g., city, country, etc.). Similarly, two-factor authentication may be beneficially implemented by authorization entity  103  when credit or debit card transaction  121  at POS merchant  102  exceeds a predetermined dollar amount, a predetermined frequency of use, and the like. In other embodiments, authorization entity  103  may require two-factor authentication as described herein for all transactions using a particular credit or debit card. 
     When authorization entity  103  receives authorization request  122  and determines the need for two-factor authentication, authorization entity  103  transmits location verification request  123  to location verification entity  104 . In some embodiments, location verification request  123  includes the location of POS merchant  102  (such as global positioning system coordinates and/or latitude-longitude coordinates). Alternatively, location verification entity  104  may already have the location of POS merchant  102  stored locally, in which case location verification request  123  may include information identifying POS merchant  102 , but no geographical or location data. Furthermore, in some embodiments, location verification request  123  includes a maximum allowable radius from the location of POS merchant  102 , within which mobile subscriber terminal  110  (and presumably card user  101 ) must be located. Alternatively, such a maximum allowable radius may instead be determined by location verification entity  104 , or may be predetermined and included in location confirmation application  105 . 
     Location verification entity  104 , upon receiving location verification request  123 , determines whether mobile subscriber terminal  110  (and, presumably, card user  101 ) is located within a maximum allowable radius of POS merchant  102 . As noted above, in some embodiments, location verification entity  104  may determine the above-described maximum allowable radius. For example, location verification entity  104  may determine the maximum allowable radius based on one or more of the identity of card user  101  or authorization entity  103 , the specific credit or debit card being used in credit or debit card transaction  121 , the location of POS merchant  102 , etc. Alternatively, authorization entity  103  may provide this maximum allowable radius to location verification entity  104 . In either case, location verification entity  104  then determines whether mobile subscriber terminal  110  is located within the maximum allowable radius of POS merchant  102  by transmitting location query  124  to location confirmation application  105  and subsequently receiving location response  125  from location confirmation application  105 . 
     Location query  124  includes the location of POS merchant  102  (for example, global positioning system coordinates and/or latitude-longitude coordinates) and, in some embodiments, the maximum allowable radius (for example in feet, meters, kilometers, etc.). By contrast, location response  125 , which is received from location confirmation application  105 , includes no geographical location information associated with mobile subscriber terminal  110  and instead includes the equivalent of either a yes or no response. In this way, two-factor authentication based on the current location of card user  101  can be used to authenticate credit or debit card transaction  121  with an automated procedure, even though card user  101  has not consented to continuously share geographical/location information with third parties (such as authorization entity  103  and location verification entity  104 ). Consequently, credit or debit card transaction  121  can be protected by the additional security associated with two-factor authentication even while card user  101  maintains electronic privacy at all times—except when performing credit or debit card transaction  121 . It is noted that by attempting credit or debit card transaction  121 , the location of card user  101  is generally revealed and recorded in any case. 
     Upon receipt of location query  124  from location verification entity  104 , location confirmation application  105  determines whether the current location of card user  101  is within a maximum allowable radius from POS merchant  102 . Generally, to make such a determination, location confirmation application  105  is configured to use location information  114  (shown in  FIG. 1 ), the location of POS merchant  102  (as provided by location verification entity  104 ), and the maximum allowable radius from POS merchant  102 , where location information  114  includes the current geographical location of mobile subscriber terminal  110 . In some embodiments, the maximum allowable radius is included in location query  124 , while in other embodiments, the maximum allowable radius or an algorithm for determining the maximum allowable radius may be downloaded as part of location confirmation application  105 . When location confirmation application  105  determines that the location of mobile subscriber terminal  110  falls outside the maximum allowable radius from POS merchant  102 , location response  125  is transmitted to location verification entity  104  and includes a “NO” indicator. When location confirmation application  105  determines that the location of mobile subscriber terminal  110  falls within the maximum allowable radius from POS merchant  102 , location response  125  is transmitted to location verification entity  104  and includes a “YES” indicator. In this way, location confirmation application  105  acts as a software token that provides a second authentication factor for debit or credit card transaction  121 . 
     In some embodiments, location confirmation application  105  stores location information  114  locally in mobile subscriber terminal  110  and may update location information  114  periodically and/or at preprogrammed times. In other embodiments, location confirmation application  105  receives location information  114  from a third party, such as a GPS-based system or cellular or WiFi network to which mobile subscriber terminal  110  is connected or may connect to or any other system capable of tracking the location of mobile subscriber terminal  110 . Examples of such systems are described below in conjunction with  FIGS. 4-7 . In such embodiments, location information  114  may be received periodically from the third party, at preprogrammed times, and/or in response to location query  124  being received from location verification entity  104 . 
     Upon receipt of location response  125  from location confirmation application  105 , location verification entity  104  transmits location verification  126  to authorization entity  103 . Location verification  126  includes either the “NO” or “YES” indicator from location response  125 . When location verification  126  includes the “NO” indicator, authorization entity  103  denies authorization request  122 , since an unauthorized user may be fraudulently using the credit or debit card associated with credit or debit card transaction  121 . Thus, authorization entity  103  transmits transaction denial  128  to the credit card console located at POS merchant  102 , to credit card user  101  directly, or to both POS merchant  102  and credit card user  101 . When location verification  126  includes the “YES” indicator, authorization entity  103  transmits authorization request  122 , since mobile subscriber terminal  110 , which presumably has the same location as card user  101 , is located at POS merchant  102 . Since the current location of card user  101  is within the maximum allowable radius of the physical location of POS merchant  102 , it may be assumed that an unauthorized user is not fraudulently using the credit card for transaction  121 . Of course, authorization entity  103  may then further base the authorization of authorization request  122  on other parameters, such as credit limit. Authorization entity  103  then transmits transaction authorization  127  to the credit card console located at POS merchant  102 . POS merchant  102  then completes credit or debit card transaction  121 . 
     In the embodiment illustrated in  FIGS. 1 and 2 , a transaction using a credit or debit card at POS merchant  102  is depicted. In other embodiments, online transactions may benefit from the use of two-factor authentication that includes verification that the current location of card user  101  is within a maximum allowable radius of a location associated with the online transaction. For example, such a location may be the geographical location associated with the IP address of a computing device associated with the online transaction. In such embodiments, a credit or debit card may not necessarily be used during the online transaction. Moreover, in such embodiments, the online transaction may include accessing an account, such as a bank account, rather than performing a credit or debit card transaction. According to some embodiments, access to the account and/or the completion of the online credit or debit card transaction is contingent on the location of a mobile subscriber terminal associated with the credit or debit card or the account being accessed. Specifically, access to the online account or completion of the online transaction is not authorized unless mobile subscriber terminal is within a maximum allowable radius of the computing device being used to initiate the online transaction or account access. The location of said computing device may be determined from the computer IP address and compared to the current location of a mobile subscriber terminal by a location confirmation application running on the mobile subscriber terminal.  FIG. 3  depicts one such embodiment. 
       FIG. 3  is a block diagram of a transaction processing system  300  illustrating an online transaction carried out according to an embodiment of the present invention. As shown, Internet user  301  uses a first authentication factor  320  to initiate an online transaction  321  using a computing device  303  connected to the Internet, such as a desktop or laptop computer, an electronic tablet, a smart phone, and the like. Via the Internet or other communication network, computing device  303  facilitates online transaction  321  with target website  302 . Target website  302  may be the website for an online merchant, a financial institution, and the like. Online transaction  321  may be a financial transaction, such as a purchase, or simply the accessing online of a password-protected account, such as an online bank account. 
     When online transaction  321  includes a credit or debit card transaction, such as an online purchase, first authentication factor  320  may include a credit or debit card number and/or other billing information. When online transaction  321  includes an access to a password-protected account, first authentication factor  320  may include a user password. Generally, online transaction  321  includes first authentication factor  320  and the IP address (or WiFi SSIDs that are visible) of computing device  303 . Upon receipt of transaction  321 , target website  302  submits an authorization request  322  to authorization entity  103 , and allows the requested online access or completes the requested online transaction when online transaction  321  is authorized by authorization entity  103  via transaction authorization  127 . 
     According to embodiments of the invention, authorization entity  103  does not authorize the transaction associated with authorization request  322  unless a two-factor authentication process involving verification of the location of Internet user  301  is successfully completed. Specifically, transaction authorization  127  is issued by authorization entity  103  if the location of Internet user  301  is verified to be within a maximum allowable radius from the physical location associated with the IP address (or WiFi SSIDs) of computing device  303 . Thus, authorization request  322  includes the IP address (or WiFi SSIDs) of and/or location information for computing device  303 , in addition to transaction information that is normally sent to authorization entity  103 , such as first authentication factor  320 . In other respects, transaction processing system  300  is substantially similar in organization and operation to transaction processing system  100  in  FIGS. 1 and 2 , in that location confirmation application  105  is configured as a software token that provides a location-based authentication factor for online transaction  321 , even when Internet user  301  has not consented to continuously provide location information to either authorization entity  103  or location verification entity  104 . 
     As noted above, in some embodiments, location confirmation application  105  may receive location information  114  (shown in  FIG. 1 ) from a third party, such as a GPS-based system or cellular or WiFi network to which mobile subscriber terminal  110  is connected or may connect to or any other system capable of tracking the location of mobile subscriber terminal  110 . One such system is illustrated in  FIG. 4 . 
       FIG. 4  is a conceptual diagram illustrating a system  400  that enables location tracking of mobile subscriber terminal  110  in a home network  401 , according to an embodiment of the present invention. Mobile subscriber terminal  110  may be any type of wireless communication device, such as a cell phone, a smart phone, etc. As shown, mobile subscriber terminal  110 , and, presumably, the user of mobile subscriber terminal  110 , is located in the primary serving network that serves mobile subscriber terminal  110 . The primary serving network of mobile subscriber terminal  110  is herein referred to as home network  401 , and the user of mobile subscriber terminal  110  is referred to herein as a mobile subscriber. 
     Home network  401  is a wireless communication system that includes at least one Mobile Switching Center (MSC)  402  serving mobile subscriber terminals, a Home Location Register (HLR)  403 , and a plurality of cell towers  461 - 465 . MSC  402  also connects the landline public switched telephone network system to home network  401 . Home network  401  may be a small network and only include a single MSC  402 . Alternatively, home network  401  may be a relatively large network, i.e., a network that services a large geographical area, and may include multiple MSCs  402 . For clarity, only a single MSC  402  is depicted in  FIG. 4 . Each MSC  402  in home network  401  has a plurality of cell towers  461 - 465  associated therewith, where each of cell towers  461 - 465  serves a specific geographical area, i.e., cells  1 - 5 , respectively. HLR  403  of home network  401  contains geographical information regarding mobile subscriber terminal  110 , where such geographical information may be a place name, a latitude-longitude coordinate, or a combination of both. Specifically, HLR  403  contains a data structure  405  that identifies the particular MSC  402  currently serving mobile subscriber terminal  110  and the closest cell tower to mobile subscriber terminal  110 . Information contained in data structure  405  includes a mobile subscriber identification number, MSC identification number (MSCID), cell tower number, mobile subscriber terminal serial number, an indicator signifying that mobile subscriber terminal  110  is in home network  401 , and other information. 
     System  400  includes a location provider  406  and a location mapping database  408 . Location provider  406  is a logical module, program, or algorithm that determines the location of mobile subscriber terminal  110  by querying location mapping database  408 . Location mapping database  408  is a data structure that maps each MSC  402  in home network  401  to a specific geographical location. In some embodiments, location mapping database  408  also maps each of cell towers  461 - 465  to a specific geographical location. In some embodiments, system  400  may be an integral part of the Operational Support System (OSS) of the cellular service provider. Consequently, location provider  406  and location mapping database  408  may be constructed, maintained, and populated by the operator of home network  401 . In other embodiments, system  400  may be a separate entity from home network  401  and therefore may be constructed, maintained, and populated by a third party. 
     Communication between home network  401  and system  400  is carried out via communication network  407 . In some embodiments, communication network  407  may comprise the Internet, the Signaling System 7 (SS7) network, the Public Switched Telephone Network (PSTN) or a combination thereof. The SS7 network is used for communicating control, status, and signaling information between nodes in a telecommunication network. 
     In operation, when mobile subscriber terminal  110  physically enters the geographical region served by home network  401 , mobile subscriber terminal  110  registers with home network  401  and MSC  402  captures the identity of the specific cell tower of cell towers  461 - 465  that is closest to mobile subscriber terminal  110 . This registration process enables mobile subscriber terminal  110  to be alerted to an incoming phone-call or message. Calls are completed and messages delivered via this closest cell tower. 
     As mobile subscriber terminal  110  changes location in home network  401 , the identity of the closest cell tower is maintained by MSC  402 . Location provider  406  periodically queries HLR  403  via communication network  407  in order to track the current MSC and/or cell tower that is closest to mobile subscriber terminal  110 . In some embodiments, the cell phone number associated with mobile subscriber terminal  110  is used to identify mobile subscriber terminal  110 . In other embodiments, location provider  406  uses a serialized equipment number associated with mobile subscriber terminal  110  to identify mobile subscriber terminal  110 . If the mobile registry is null, i.e., mobile subscriber terminal  110  is not currently registered in home network  401 , then a “not-in-network” message is returned to location provider  406  by HLR  403 . 
     After location provider  406  receives a reply from HLR  403  that identifies the closest MSC and/or cell tower to mobile subscriber terminal  110 , location provider  406  queries location mapping database  408  via query  409 . Query  409  includes the MSCID of said MSC and/or the appropriate cell tower number. Location mapping database  408  then returns the geographical location of MSC  402  to location provider  406  via reply  410 . In some embodiments, the granularity of position of mobile subscription terminal  110  is enhanced by also providing cell tower location in reply  410 . In other embodiments, inclusion of the geographical location of MSC  402  in reply  410  is sufficient. Thus, location provider  406  is continuously updated with the current geographical location of mobile subscriber terminal  110  and, presumably, the mobile subscriber, and consequently can provide such location information to any authorized party. For example, in some embodiments, system  400  may be configured to provide the current geographical location of mobile subscriber terminal  110  directly to mobile subscriber terminal  110 . In other embodiments, system  400  may be configured to provide the current geographical location of mobile subscriber terminal  110  to location verification entity  104  in  FIG. 1 . 
       FIG. 5  schematically illustrates the contents of location mapping database  408 , according to an embodiment of the invention. As shown, location mapping database  408  provides mappings of MSCs to the physical location of the area served by each MSC. In some embodiments, location mapping database  408  also includes the geographical locations corresponding to each subtending cell tower of each MSC included in mapping database  408 . 
       FIG. 6  is a conceptual diagram illustrating a system  600  that enables location tracking of a mobile subscriber terminal  110  in roaming mode outside home network  401 , according to an embodiment of the present invention. As shown, mobile subscriber terminal  110 , and presumably also the mobile subscriber, is roaming outside home network  401  and is physically located in a roaming network  501 , such as a cell phone network in a foreign country. 
     Roaming network  501  is substantially similar in organization and operation to home network  401 , and includes one or more MSCs  502 , each with its attendant cell towers  661 - 665 . In addition to HLR  403 , home network  401  includes a remote HLR, herein referred to as HLR-R  503 . HLR-R  503  contains information regarding the MSC  502  in roaming network  501  in which mobile subscriber terminal  110  has registered. Similar to HLR  403 , HLR-R  503  contains geographical information regarding mobile subscriber terminal  110 . In contrast to HLR  403 , HLR-R  503  contains a data structure  505  that identifies the particular MSC  502  in roaming network  501  that is currently serving mobile subscriber terminal  110 . Information contained in data structure  505  includes a mobile subscriber identification number, MSC identification number, mobile subscriber terminal serial number, etc. In some embodiments, data structure  505  may also include the cell tower number of the closest cell tower to mobile subscriber terminal  110 . 
     System  600  is substantially similar in organization and operation to system  400  in  FIG. 4 . One difference between system  600  and system  400  is that system  600  includes a location mapping database  608 , analogous to mapping database  408 , that maps each MSC  502  in one or more roaming networks, e.g., roaming network  501 , to a specific geographical location. In some embodiments, location mapping database  608  also maps each of cell towers  661 - 665  to a specific geographical location. In some embodiments the database  608  also maintains a record of the last location mapped for the mobile subscriber terminal. 
     When mobile subscriber terminal  110  is outside home network  401 , roaming network  501  accepts registry of mobile subscriber terminal  110 , assuming there is a roaming agreement between the operator of home network  401  and the operator of roaming network  501 . As part of normal operation of home network  401  and roaming network  501 , the identity of mobile subscriber terminal  110  is communicated over a telephony signaling network  510  to home network  401 , together with the appropriate MSC identification for MSC  502  for inclusion in data structure  505 , where MSC  502  is the MSC currently serving mobile subscriber terminal  110 . Such information that is communicated from roaming network  501  to home network  401  may be maintained in roaming network  501  in a database equivalent to data structure  405  in HLR  403  for mobile subscriber terminals from other networks, i.e., mobile subscriber terminals roaming in roaming network  501 . This database containing information related to roaming subscriber units is called the Visitor Location Registry (VLR). 
     In operation, location provider  606  queries home network  401  regarding the location of mobile subscriber terminal  110 . When HLR  403  is queried by location provider  606 , mobile subscriber terminal  110  is discovered to be roaming. Location provider  606  then queries HLR-R  503 , and receives the MSC ID of MSC  502 , which is the MSC currently serving mobile subscriber terminal  110  in roaming network  501 . The geographical location of mobile subscriber terminal  110  is then obtained from location mapping database  608  in the same way that system  400  obtains geographical location for mobile subscriber terminal  110  from location mapping database  108 . Thus, location provider  606  is continuously updated with the current geographical location of mobile subscriber terminal  110 , even when mobile subscriber terminal  110  is located in a foreign country or otherwise roaming outside home network  401 . Consequently, location provider  606  can readily provide location information for mobile subscriber terminal  110  to any authorized party, e.g., employer, spouse, bank, online merchant, etc. 
       FIG. 7  schematically illustrates the contents of mapping database  608 , according to an embodiment of the invention. Location mapping database  608  is substantially similar in organization to mapping database  408 , except that, at a minimum, location mapping database  608  provides mappings of roaming MSCs to the physical location of the area served by all included roaming MSCs. Specifically, the roaming MSCs are selected from one or more roaming networks, e.g., roaming network  501 , and not home network  401 . Other elements of location mapping database  608  that are enhancements over prior art location mapping databases may include serving cell tower ID  601 , latitude/longitude coordinate  602 , timestamp  603 , and error radius  604 . The information contained in location mapping database  608  may be generated and maintained by home network  401  by surveying roaming network operators on an on-demand or on a scheduled basis. 
       FIG. 8  is a flow chart that summarizes, in a stepwise fashion, a method  800  for authenticating a user activity based on a location of a mobile communication device associated with a user without receiving location data for the device, according to an embodiment of the invention. By way of illustration, method  800  is described in terms of a transaction processing system substantially similar in organization and operation to transaction processing system  100  in  FIG. 1  and system  300  in  FIG. 3 . Other transaction processing systems may also benefit from the use of method  800 . Although the method steps are described in conjunction with  FIGS. 1 and 3 , persons skilled in the art will understand that any system configured to perform the method steps falls within the scope of the present invention. 
     Prior to method  800 , the user of mobile subscriber terminal  100  initiates user activity that may require authorization to be completed. In some embodiments, the user activity includes using computing device  303  to perform an online transaction  321 , for example requesting access to a secure account via the Internet (see  FIG. 3 ). In other embodiments, the user activity includes attempting to make debit or credit card transaction  121  at POS merchant  102  (see  FIG. 1 ). When the user attempts to initiate the activity, “two-factor” authorization may be implemented via method  800  as described herein. POS merchant  102  or target website  302  then transmits an authentication request (authorization request  122  or authorization request  322 , respectively) to an authorization entity, such as authorization entity  103 . Authorization entity  103  then transmits location verification request  123  to location verification entity  104 . 
     The method begins in step  801 , in which location verification entity  104  determines a location of a user activity that requires authentication. As noted above, the user activity may be debit or credit card transaction  121  or online transaction  321 . In some embodiments, location verification entity  104  determines the location of the user activity by receiving data that are transmitted with authorization request  122  or authorization request  322 , and which indicate the location of the user activity. For example, geographical coordinates associated with the IP address of computing device  303  or the location of POS merchant  102  may be received in step  801  by location verification entity  104 . Alternatively, location verification entity  104  may already have the location of POS merchant  102  or computing device  303  stored locally, in which case location verification request  123  may include information identifying POS merchant  102  or computing device  303 , but no explicit geographical or location data. 
     In step  802 , location verification entity  104  formulates an authentication inquiry that includes the location of the user activity. For example, in some embodiments, location verification entity  104  formulates location query  124 . In some embodiment, location query  124  includes a maximum allowable radius, as described above, to facilitate the subsequent generation of an authentication response by mobile subscriber terminal  110 . In step  803 , location verification entity  104  transmits location query  124  to location confirmation application  105 , which is running on mobile subscriber terminal  110 . 
     In step  804 , location confirmation application  105  in mobile subscriber terminal  110  detects that location query  124  has been received through wireless communication module  113  of mobile subscriber terminal  110 . In step  805 , responsive to the detection of location query  124  being received through wireless communication module  113 , location confirmation application  105  compares location information  114  (i.e., the current location of mobile subscriber terminal  110 ) with data that are included in location query  124  and indicate the location of the user activity. In step  806 , location confirmation application  105  transmits an authentication response (i.e., location response  125 ) based on the proximity of the current location of mobile subscriber terminal  110  with respect to the location of the user activity. It is noted that location response  125 , which is received from location confirmation application  105 , includes no geographical location information associated with mobile subscriber terminal  110  and instead indicates whether mobile subscriber terminal  110  is located within the maximum allowable radius from the location of the user activity. 
     In step  807 , location verification entity  104  receives location response  125  from mobile subscriber terminal  110 . In step  808 , location verification entity  104  authenticates the user activity according to location response  125  received in step  807 , for example by transmitting location verification  126  to authorization entity  103 . Specifically, when location response  125  indicates that mobile subscriber terminal  110  is located within the maximum allowable radius from the location of the user activity, location response  125  includes a “YES” indicator and authorization entity  103  may authorize the user activity. Alternatively, when location response  125  indicates that mobile subscriber terminal  110  is located outside the maximum allowable radius from the location of the user activity, location response  125  includes a “NO” indicator and authorization entity  103  denies the requested user activity. 
     In sum, one or more embodiments of the invention provide techniques for providing a two-factor authentication process for a credit card transaction, where the second authentication factor includes verification of user location at the time of the transaction. Advantageously, such verification of user location may be accomplished without user location being continuously tracked. Consequently, convenient and reliable location-based two-factor verification is made possible even when a user of a mobile subscriber terminal has not consented to being continuously tracked. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.