Abstract:
Method and system integrating wireless/wireline and circuit/packet networks (to bypass GSM Memorandum of Understandings) for cellular/PCS services so that GSM subscribers roaming into CDMA networks can be provided with basic wireless call delivery services as long as the roamers can pay the bill with their valid credit card. This is achieved by integrating wireless and wireline networks as well as circuit and packet networks, using IP networks and protocols as an alternative to the existing telephony-based approach.

Description:
RELATED APPLICATIONS 
     Not Applicable. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to cellular or wireless call delivery services provided by cellular/PCS operators. Call delivery service permits a cellular or wireless subscriber to receive phone calls either in a home network (e.g., London) or while away from the home network (e.g., in Chicago). 
     Global Systems for Mobile Communications (GSM) is a widely popular Time Division Multiple Access (TDMA)-based standard used in Europe. TDMA is a digital wireless technology. 
     A subscriber who roams to Code Division Multiple Access (CDMA) wireless networks may be denied wireless services even if the subscriber&#39;s mobile device is capable of dual-mode (CDMA or analog, and GSM) operation, and the subscriber has the ability to pay for wireless calls with his/her valid credit card. The basis for the denial of service is simply because there is a lack of a GSM Memorandum of Understanding (MoU) between the home GSM network and visited CDMA network for billing settlement. 
     1. Field of the Invention 
     The present invention relates to the field of Internet Protocol as used to replace traditional telephony infrastructure for roaming wireless users. The present invention also relates to the field of providing mobile wireless telephone service for users roaming outside their own predefined service area. The present invention also relates to the field of inter-operability of CDMA and GSM/TDMA wireless networks. 
     2. Description of Related Art 
     A GSM MoU is an agreement between a consortium of GSM wireless service providers. For example, a subscriber of a first GSM service provider may roam to a service area controlled by a second GSM service provider. An established MoU allows the first GSM service provider to still serve the subscriber while that subscriber is in the service area corresponding to the second GSM service provider. In practice, the second GSM service provider gets paid a portion of the service/roaming charge the first GSM service provider charges the subscriber, which is one reason why wireless “roaming charges” are so expensive. 
     The Local Number Portability (LNP) feature could be used, to some extent, to bypass GSM MoU. LNP allows a telephone subscriber to “port” his/her phone number when that subscriber relocates to a different region of the country, even when the local area code may be different (e.g., a subscriber may reallocate from Chicago to New York, but still keep the original phone number used in Chicago which has an area code of 312). 
     However, LNP updates are not dynamic by design and thus can have serious limitations. A subscriber who wants LNP typically will request that service by filling out a form. The phone company&#39;s administrative staff will manually process the form and make necessary updates of various databases to effect the requested LNP. Note that LNP is designed to support occasional change of location/re-location, and is typically done manually, thus there is a scalability issue in practice. 
     Public Switched Telephony Network (PSTN) refers to the public phone networks as we know them. PSTN is composed of switches and T1/E1 trunks, central office, etc. PSTN uses circuit-switched technology, in which necessary resources are allocated (dedicated) for the duration of a phone call. An IP network (e.g., the Internet), in contrast, is composed of nodes of computers, serves, routers, and communications links, etc. It employs packet-switching technology which decomposes data (e.g., voice, web pages, an e-mail message) into IP packets. Each packet is then transmitted over an IP network to a destination identified by an IP address and reassembled at the destination. An IP transmission is completed without pre-allocating resources from point to point. 
     Dynamic Host Configuration Protocol (DHCP) service provides a dynamic IP address with a short term lease. DHCP is covered by RFC 2131. As of the date of this disclosure, RFC 2131 may be obtained from URL http://nic.mil/ftp/rfc/rfc2131.txt. The major use of DHCP is to support dynamic IP address assignment. For example, an ISP (Internet Service Provider) can use DHCP to dynamically assign an IP address to a subscriber after he/she logs in over a dial-up connection; once the session is over, the IP address is recycled for other dial-in users. 
     Mobile IP is described by Internet Engineering Task Force (IETF) Request for Comments (RFC) number 2002. As of the date of this disclosure, RFC 2002 may be obtained from URL http://nic.mil/ftp/rfc/rfc2002.txt. Unlike H.323, Mobile IP does supports packet mobility, but smooth handoffs—as smooth as circuit cellular voice—are not supported. 
     The Diffie-Hellman algorithm is a math method allowing two parties to establish a temporary secret for secure transmission of information. This technique is detailed in: Diffie, W. and Hellman, M., “New directions in cryptography,”  IEEE Transactions on Information Theory,  Vol. IT-22, Nov. 1976, pp. 644-654. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above issues of denial of service by combining and integrating the proper pieces of circuit and packet, and that of wireless and wireline. The present invention provides a way to bypass GSM MoU so that GSM users roaming into CDMA networks, having the ability to pay wireless calls with a credit card, can be provided with basic call delivery wireless services. 
     These and other aspects and attributes of the present invention will be discussed with reference to the following drawings and accompanying specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 represents a prior art typical infrastructure supporting call origination and call delivery. 
     FIG. 2 represents the infrastructure supporting the first step of call delivery in accordance with the present invention. 
     FIG. 3 represents the infrastructure supporting the second step of call delivery in accordance with the present invention. 
     FIG. 4 represents the infrastructure supporting the third step of call delivery in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the present invention is susceptible of embodiment in many different forms, there is shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     Cellular telephone users generally subscribe to a cellular service provider. The subscriber may use their mobile devices within the home wireless network served by their wireless service provider in exchange for subscription fees. However, users also may travel, and thus need to have their mobile devices operate outside of their home wireless networks as they visit other areas. 
     FIG. 1 shows a typical wireless infrastructure that provides cellular/PCS services such as call origination and call delivery for a roaming mobile device. For call delivery, the visited network  100  tracks the location of a roaming mobile device  140  and the Visitors Location Register (VLR)  120  reports that location information to the Home Location Register (HLR)  160  typically via a GSM MAP network or an ANSI-41 network. An Authentication Center (AC)  170  in the home network  150  is used for user registration and authentication (e.g., checking to see, among other things, if the user has made payments). When an incoming call  165  is to be delivered to a subscriber, the HLR  160  is contacted first about the whereabouts of the current VLR  120 , and the call is then redirected via links  167  and the Public Switched Telephony Network (PSTN)  180  to the Mobile Switching Center (MSC)  110  currently serving the mobile device. 
     An MSC is a telephone switch specialized for wireless and mobility support. An MSC performs various functions, including mobility management, call handoffs, call admission, call control, resource allocation, and so forth. The redirected call  167  is then relayed from the MSC  110  via wireless transmission from a base stations  105  to the mobile device  140 . 
     Since the visited network  100  and home network  150  may be operated by different wireless operators, certain kinds of business roaming agreements are necessary for things like billing settlement. In GSM networks, a GSM Memorandum of Understanding (MoU) serves that purpose. 
     Table 1 summarizes the current cellular/PCS technologies and the network elements that are involved in call origination and call delivery. 
     
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Cellular Value Proposition 
                 Current Supporting Cellular/PCS Technologies 
               
               
                   
               
             
             
               
                 Wireless and mobility 
                 Base stations, RF engineering, hard and soft handoffs 
               
               
                 Wide Coverage Area 
                 Automatic roaming across visited &amp; home cellular networks using 
               
               
                   
                 VLR/HLR/AC 
               
               
                   
                  US: ANSI-41 and business roaming agreements 
               
               
                   
                  GSM: GSM MAP and GSM Memorandum of Understandings 
               
               
                 Reliable services of both 
                 Call origination: involves VLR, HLR, and AC for service 
               
               
                 voice/data call origination 
                 qualification, user service profile, and billing. 
               
               
                 voice/data call delivery 
                 Call delivery: involves VLR and HLR for mobile location tracking, 
               
               
                   
                 Temporary Local Directory Number (TLDN) assignment, call 
               
               
                   
                 forwarding/routing, and billing. 
               
               
                   
               
             
          
         
       
     
     A problem occurs when a GSM user, who roams to CDMA (or TDMA) networks, may not be provided with wireless services simply because there lacks a GSM Memorandum of Understandings (MoU) between the home GSM network and visited CDMA network. This is so even when the user&#39;s mobile device  140  is capable of dual-mode (CDMA or analog, and GSM) operation, and the user has the ability to pay for wireless calls (e.g., call delivery) with his/her valid credit card. 
     The present invention combines the following technical components to bypass GSM MoU for call delivery (i.e., incoming calls): use of IP to transport packet voice; use of the user&#39;s credit card as a payment method; and use of the Diffie-Hellman algorithm to encrypt the user&#39;s credit card information for over-the-air transmission. 
     The conversion of packet voice to circuit voice leverages the existing smooth handoff capability of circuit cellular voice and the well-engineered CDMA/TDMA circuit-mode air interface that provides superior efficiency of radio resource usage. The conversion also allows the roamer to receive call delivery with an existing cell phone or mobile device as opposed to having to purchase a new kind of “packet phone.” 
     FIGS. 2,  3 , and  4  use many of the same reference numbers to identify common features; it is to be understood that where the same number is used, it refers to the same feature in each of the drawings. 
     FIG. 2 shows the first step of call delivery in one embodiment of the present invention, wherein prior to roaming the mobile user sets up call forwarding from the home wireless network  250 . The home wireless service provider contacts a voice and data service provider&#39;s network  252 , which provides (1) a telephone number  242  for call forwarding to the user&#39;s mobile device  240 , (2) an IP address  244  within the voice and data service provider&#39;s network, and (3) a shared secret  243  between the mobile device and the voice and data service provider&#39;s network. These numbers  242 ,  243 , and  244  are provisioned and stored within the user&#39;s mobile device. The IP address  244  allows the voice and data service provider&#39;s network  252  to be contacted via an IP network (e.g., the Internet). 
     FIG. 3 shows the second step of call delivery in one embodiment of the present invention, wherein the user&#39;s mobile device  240  is roaming in a visited wireless network  200 . As the user powers on the mobile device  240 , the mobile device registers with the visited wireless network  200 . This registration permits the visited wireless network  200  to track the mobile&#39;s location and perform call delivery, but does not imply conventional VLR  220 /HLR  260  interaction. In accordance with the present invention, the roamer&#39;s HLR  260  and the roamer&#39;s Authorization Center (AC)  270  of the home wireless network  250  are not contacted for call delivery. This registration conveys the mobile device&#39;s International Mobile Subscriber Identification (IMSI), the forwarding phone number  242 , and the IP address  244  to the visited MSC  210 . 
     With the roamer&#39;s IMSI, forwarding number  242 , and IP address  244 , the visited MSC  210  identifies the user&#39;s mobile device  240  as a special phone supporting the present invention. This special identification aborts the conventional VLR/HLR interaction. 
     The visited MSC  210  and the user&#39;s mobile device  240  interact with each other to establish a temporary shared secret  245  using the Diffie-Hellman algorithm. This mechanism is also used in Cellular Digital Packet Data (CDPD) networks typically used for low speed packet data services. The user&#39;s credit card information is transmitted from the mobile device to the visited network via wireless communication with base stations  205  using the established temporary shared secret  245 . The temporary shared secret permits the sensitive information of the user&#39;s credit card information to be relayed to the visited wireless network  200  securely. 
     The credit card information can be entered by the user on the phone keypad, or via a swipe of the card through a card reader slot on the phone, or via some other means. In one embodiment, the credit card information is optionally stored within the mobile device. In another embodiment, the credit card information must be entered by the user for each use. In another embodiment, the user selects a credit card number from a list to be used for the outgoing call. The credit card number may belong to the user, the user&#39;s employer, or another third party. The credit card number thus relayed securely is then verified by the visited network&#39;s billing server to ensure it is valid, using methods familiar to anyone exposed to credit card payments and transactions and thus not detailed herein. 
     After credit card verification, the visited MSC  210  contacts the voice and data service provider&#39;s network  252  using the IP address  244 . A request is made to set up an IP connection  285  between the user&#39;s mobile device and the voice and data service provider&#39;s network  252  which is signed using the Mobile IP shared secret  243 , which permits the voice and data service provider&#39;s network to authenticate the request. Authentication is required because otherwise it would be possible for a third party to fraudulently impersonate the user&#39;s mobile device, thus denying service to the user. Upon authentication, the voice and data service provider&#39;s network assigns a dynamic IP address  247  to the user&#39;s mobile device  240  via DHCP and relays it to the user&#39;s mobile device. 
     Upon assignment of the dynamic IP address  247 , the voice and data service provider&#39;s network  252  updates its phone-number-to-IP-address table  275  that maps the user&#39;s forwarding phone number  242  to the dynamic IP address  247  now assigned to the user&#39;s mobile device  240 . Mobile IP binding tables, which are discussed at length in RFC 2002, permit tracking the location of the user&#39;s mobile device as it registers with various visited wireless networks. 
     The visited wireless service provider similarly updates its IP-address-to-phone-number table  215  that maps the dynamic IP address of the mobile  247  to the forwarding phone number  242  provided by the home wireless service provider. When both wireless service providers&#39; tables  215 ,  275  are updated and the IP connection  285  is established, the setup for the PSTN bypass is complete. 
     FIG. 4 shows the last step of call delivery in one embodiment of the present invention. An incoming call  257  to the user is forwarded by the home MSC  265  using the forwarding phone number  242  and thus to the voice and data service provider&#39;s network  252 . The voice and data service provider&#39;s network  252  looks up the phone number  242  in its phone-number-to-IP-address table  275  and finds the dynamic IP address  247  that has been assigned to the user&#39;s mobile device  240 . In a preferred embodiment, additional routing information (e.g., the IP address of the conversion server  287 , or a preferred route for IP connection  285 ) are also maintained and utilized for data packet forwarding by the voice and data service provider&#39;s network. 
     The voice and data service provider&#39;s network  252  converts via conversion server  283  the circuit call to a packet call (i.e., voice-over-IP) and forwards the packets via the IP connection  285  to the visited wireless network. In a preferred embodiment, the PSTN bypass is an IP network such as the Internet. In alternate embodiments, the PSTN bypass may be a private IP network, or a combination of both private networks and the public Internet. In another embodiment, the PSTN bypass may be implemented as an IP tunnel through the public Internet and/or private IP networks. Further, the IP network and/or IP tunnel may be layered on top of a different network infrastructure, in a manner consistent with current practice. 
     An IP tunnel is a specific case of a general network tunnel, which typically has two ends, and encapsulates packets of a first protocol for transmission from the first end to the second end of the tunnel using a potentially different second protocol for actual routing and delivery. Setting up a network tunnel generally involves a server or agent setting up each end prior to use. IP tunneling allows Internet standard-based routers to route IP packets from one end of a tunnel to the other end of the tunnel, regardless of the topology of the underlying IP network. A detailed technical discussion of IP tunneling may be located in RFC 2002 which pertains to support of Mobile IP. 
     The visited wireless network  200  looks up the dynamic IP address  247  in its IP-address-to-phone-number table  215  and finds the phone number  242  that has been assigned to the user&#39;s mobile device  240  for roaming. 
     The visited wireless network  200  converts via conversion server  287  the packets received via the IP connection  285  to a circuit call  212  and relays the circuit call to the visited MSC  210 . The visited MSC  210  forwards the circuit call  212  on to the base stations  205  for over-the-air transmission to the user&#39;s mobile device  240 . 
     In a preferred embodiment, the conversion servers  283 ,  287  are respective servers in the voice and data service provider&#39;s network and the visited wireless network which comply to the H.323 standards, which perform both packet-to-circuit and circuit-to-packet conversions in both locations  200 ,  252 , thus supporting speaking by either the calling or called party. H.323 is a list of standards that supports voice over IP. As of the date of this disclosure, the URL http://www.databeam.com has further information on the H.323 standards. In this embodiment, packet data is conveyed in both directions over the IP connection  285 , and is converted appropriately to circuit calls by the H.323 servers at each end appropriately for interface to wireless (or in the case of the home network, wireline) communications. 
     When the call is terminated, billing information is collected in the visited network&#39;s billing server  290 . The billing information may include but is not limited to at least one of the duration of the call, which PSTN bypass was used, which credit card number was used, time and date, and other kinds of billing data. At the end of a billing period, or when the accumulated bill amount exceeds some predetermined amount, or when additional services or processing fees may be imposed, or at some other preferential time, the visited network&#39;s billing server  290  interacts with the credit card&#39;s billing server  295  for billing settlement, using the traditional and well-understood practices for accounting for services rendered. In accordance with the present invention, the roamer&#39;s HLR  260  and the roamer&#39;s AC  270  are not contacted for call delivery by the VLR  220 . 
     The system of the present invention provides basic wireless call delivery service. The user must have a mobile device and subscribe to a home wireless service provider. The home wireless service provider serves a home wireless network. When the user travels to visit an area outside the home wireless network that action is called roaming. 
     Visited wireless service providers serve visited wireless networks, which are distinct and separate from the home wireless network. If there does not exist a pre-arranged Global Systems for Mobile Communications (GSM) Memorandum of Understanding (MoU) between the home wireless service provider and the visited wireless service provider, but the user does have a payment means to pay for the basic wireless call delivery service, the invention permits basic wireless delivery service. 
     The preferred embodiment of the present invention includes payment identification means. The payment identification means is for identifying the user&#39;s payment means to the visited wireless service provider. The preferred embodiment also includes a Public Switched Telephony Network (PSTN) bypass for conveying data as packet data independently of an existing PSTN, and also independently of a GSM MAP network or an ANSI-41 network. This allows for potential cost savings by not using the existing PSTN infrastructure and supporting networks to carry the call and call setup information. 
     The preferred embodiment of the present invention includes delivery service means for providing basic wireless call delivery service via the PSTN bypass. The delivery service means is typically responsive to the payment identification means. The system may also include collection means for collecting billing information from the visited wireless network by the visited wireless service provider. This billing information typically originates from the delivery service means. The system may further include billing means for billing the user by the visited wireless service provider. The billing amounts are typically determined by the collection means and also usually rely on the payment identification means. 
     The PSTN bypass may be any embodiment of network, including an IP network. The PSTN bypass may also incorporate an IP tunnel, which may tunnel through an IP network or another kind of network. 
     The payment means of the present invention preferably comprises credit card information. Typically, the credit card information is relayed securely from the user&#39;s mobile device to the visited wireless network. The secure relay can be accomplished by establishing a Diffie-Hellman temporary shared secret between the user&#39;s mobile device and the visited wireless network. The shared secret permits secure transmission of the user&#39;s credit card information to the visited wireless service provider via the visited wireless network. Upon receipt, the visited wireless service provider is then able to verify the validity of the user&#39;s credit card information. 
     The credit card information may be stored within the user&#39;s mobile device. The user may enter the information using a keypad, or with a card reader, swiper, or scanner. Alternatively, a third party may enter the information, or the mobile device may be pre-programmed with the information. The system of the present invention may also include an IP connection means to establish the PSTN bypass via an IP network. 
     The system of the present invention may utilize a circuit conversion means to convert circuit calls destined for the user&#39;s mobile device to packets for conveyance via the IP connection means. If so, it also includes packet conversion means to convert the packets conveyed by the IP connection means back to a circuit call for delivery to the user&#39;s mobile device. In the preferred embodiment the circuit conversion means is typically an H.323 server. The packet conversion means is also typically an H.323 server in the preferred embodiment. 
     The system of the present invention may also include lookup tables or database systems that include a phone-number-to-IP-address table in the home wireless network and an IP-address-to-phone-number table in the visited wireless network. If these tables are present, the system preferably includes means to update each of these tables. 
     The system of the present invention may also include a forwarding means for setting up call forwarding in the home wireless network. Typically, the home wireless service provider sets up call forwarding for the user. This setup may include obtaining a telephone number for call forwarding from the home wireless network. The setup may also include obtaining an IP address corresponding to the home wireless service provider, or some subsystem supplied by the home wireless service provider. These pieces of data are typically sent to and stored within the user&#39;s mobile device. The system also may include Dynamic Host Configuration Protocol (DHCP) to obtain a dynamic IP address from the home wireless service provider. 
     The system of the present invention also may include a Public Switched Telephony Network (PSTN) bypass means. This bypass typically includes a first end and a second end. This bypass is typically used for conveying packets in both directions between the first end and the second end. 
     The system of the present invention also may include delivery service means. The delivery service means is typically used for providing basic wireless call delivery service via the PSTN bypass means. The delivery service means typically only functions if the system knows the user has a means to pay for the service. 
     To allow the system of the present invention to know if the user has a means to pay for the service, the system may include a payment identification means for identifying the user&#39;s payment means. The visited wireless service provider typically collects and compiles billing information based on the delivery service, and subsequently bills the user based on that billing information. 
     The system of the present invention may also include a first end means to establish the first end of the PSTN bypass within the home wireless network. If so, it also typically includes a second end means to establish the second end of the PSTN bypass within the user&#39;s mobile device. In one embodiment, the present invention includes a circuit conversion means to convert circuit calls to the mobile device to packets for conveyance via the PSTN bypass, and a packet conversion means to convert the packets conveyed by the PSTN bypass to a circuit call. In a preferred embodiment, the circuit conversion means is an H.323 server and the packet conversion means is also an H.323 server. 
     The method of the present invention permits providing basic wireless call delivery service for a user having a mobile device and roaming to an area not covered by a GSM MoU. The method includes the step of registering with the user&#39;s home wireless service provider. The registration is to establish call forwarding within the home wireless network, among other things. The method also includes the step of identifying the user&#39;s payment means to the visited wireless service provider. The method utilizes a provided Public Switched Telephony Network (PSTN) bypass for conveying data as packet data independently of any existing PSTN. 
     The preferred method of the present invention also includes registering with the visited wireless service provider. This registration is to establish the PSTN bypass through to the user&#39;s mobile device, and determining how the user will pay for the service, among other things. The method includes the step of delivering calls to the user&#39;s mobile device via the PSTN bypass, collecting billing information, and billing the user for the service. The PSTN bypass of the present method can be an IP network or any other kind of network, and it can be implemented via an IP tunnel. 
     The method of the present invention can communicate the user&#39;s payment information, which may be credit card information, via a secure transmission. The transmission is made secure by the use of the Diffie-Hellman math method, which involves a shared secret between the user&#39;s mobile device and the visited wireless service provider. 
     The method of the present invention includes the step of registering with the user&#39;s home wireless service provider, which typically includes at least obtaining an IP address corresponding to the home wireless service provider and obtaining a telephone number for call forwarding from the home wireless network. It may also include storing this information in the user&#39;s mobile device. 
     The method of the present invention includes the step of registering with the visited wireless service provider, which typically includes at least obtaining a dynamic IP address from the home wireless service provider by the visited wireless service provider using DHCP. It may also include relaying the dynamic IP address from the visited wireless service provider to the user&#39;s mobile device, and establishing a PSTN bypass via an IP connection to the user&#39;s mobile device. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.