Abstract:
A general global gateway (GGG) permits authenticating between a CDMA network and a GSM network such that a mobile station having a subscription in a GSM network can roam into a CDMA network and be authenticated to use the CDMA network. The GGG obtains authentication parameters from the mobile station and determines whether the authentication parameters satisfy GGG authentication criteria. During the authentication process, the mobile station is placed in “SMS only” status until authorized by the GGG. Checks are made during the authentication process to assure the GGG and mobile station agree on the number of GSM network accesses and to assure the mobile station is authorized for GSM access for a time period.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority from U.S. Provisional Patent Application Ser. No. 60/455,909, filed Mar. 18, 2003. 
   REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT 
   The present Application for Patent is related to the following co-pending U.S. Patent Applications: 
   “Internetworking Between A First Network And A Second Network” filed on Mar. 18, 2004, having Ser. No. 10/804,265, and “Using Shared Secret Data (SSD) To Authenticate Between A CDMA Network And A GSM Network,” filed on Mar. 18, 2004, having Ser. No. 10/804267, assigned to the assignee hereof, and which are expressly incorporated by reference herein. 

   FIELD OF THE INVENTION 
   The present invention relates generally to wireless communication systems, and more particularly to systems that permit authenticating between a CDMA network and a GSM network. 
   BACKGROUND 
   Code division multiple access (CDMA) is a digital wireless technology that inherently has relatively greater bandwidth capacity, i.e., that inherently permits the servicing of more telephone calls per frequency band, than other wireless communication technologies. Moreover, the spread spectrum principles of CDMA inherently provide secure communications. U.S. Pat. No. 4,901,307, incorporated herein by reference, sets forth details of a CDMA system, which can be used to transmit both voice calls and non-voice computer data. 
   Despite the advantages of CDMA, other wireless systems exist that use other principles. For example, in much of the world GSM is used, which employs a version of time division multiple access. 
   Whether CDMA principles or other wireless principles are used, wireless communication systems can be thought of as having two main components, namely, the wireless radio access network (RAN) and the core infrastructure which communicates with the RAN and with external systems, such as the public switched telephone network (PSTN), the Internet (particularly although not exclusively for data calls), etc. The core infrastructures associated with the various wireless technologies can be very expensive, both in terms of hardware and in terms of developing communication protocols to support particularized, typically system-specific call switching, subscription and attendant authentication and call monitoring, and billing. Consequently, the communication protocols of one wireless system (in the case of GSM, GSM protocols, and in the case of CDMA such as cdma2000-1x, IS41 protocols) may not be compatible with those of another system without expensively prohibitive alterations in the core infrastructure of one system or the other. 
   It would be desirable to authenticate between a CDMA network and a GSM network, thereby enabling the use of a CDMA-based RAN, with its attendant advantages, and enabling the use of a GSM-based core infrastructure, since GSM is extant in much of the world. 
   Thus, a dual-mode mobile station may be enabled to advantageously interface with a GSM core infrastructure when in, e.g., Europe, and to use a CDMA infrastructure when in, e.g., the United States. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a general global gateway (GGG) is configured to support communication between a GSM network and a CDMA network to enable a mobile station (MS) subscribed in the GSM network to communicate using the CDMA network, comprising a database configured to store a number of times the mobile station has accessed the GGG, and a logic unit configured to execute program logic to determine whether a parameter received from the mobile station, the parameter representing a count of a predetermined event that is a mutually agreed upon event between the GGG and mobile station. 
   In another aspect of the invention, a general global gateway (GGG) is configured to support communication between a GSM network and a CDMA network to enable a mobile station (MS) subscribed in the GSM network to communicate using the CDMA network, comprising means for storing a number of times the mobile station has accessed the GGG, and means for executing program logic to determine whether a parameter received from the mobile station, the parameter representing the number of times the mobile station has accessed the GGG, is equal to the stored number of times the mobile station has accessed the GGG. 
   In yet another aspect of the present invention, a method of wireless communications between a GSM network and a CDMA network to enable a mobile station (MS) subscribed in the GSM network to communicate using the CDMA network, comprises storing a number of times the mobile station has accessed a general global gateway (GGG), and determining whether a parameter received from the mobile station, the parameter representing the number of times the mobile station has accessed the GGG, is equal to the stored number of times the mobile station has accessed the GGG. 
   In a further aspect of the present invention, computer readable media embodying a program of instructions executable by a computer program to perform a method of wireless communications between a GSM network and a CDMA network enabling a mobile station (MS) subscribed in the GSM network to communicate using the CDMA network, the method comprises storing a number of times the mobile station has accessed a general global gateway (GGG), and determining whether a parameter received from the mobile station, the parameter representing the number of times the mobile station has accessed the GGG, is equal to the stored number of times the mobile station has accessed the GGG. 
   It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a block diagram of a wireless communications system comprising a CDMA network, a GSM network, General Global Gateway (GGG), and mobile stations; and 
       FIGS. 2   a  and  2   b  shows a flowchart for authenticating a CDMA mobile station  24  with a subscription in a GSM network  14  in accordance with an embodiment. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a block diagram of a wireless communications system  10  comprising a CDMA network  12 , a GSM network  14 , General Global Gateway (GGG)  16 , and mobile stations  18 ,  20 ,  22 ,  24 . GSM mobile station  20  includes a Subscriber Identity Module (SIM)  26 . CDMA mobile station  24  includes SIM  28 . SIMs  26 ,  28  are removable engaged with mobile stations  20 ,  24 , respectively, in accordance with principles known in the art. In an embodiment, the GGG is a GSM Global Gateway. 
   The GGG  16  internetworks between the CDMA network  12  and the GSM network  14 . The GGG includes a transceiver (not shown) that allows it to send and receive messages to and from the CDMA network  12  and the GSM network  14 . 
   In an embodiment, the CDMA network is an ANSI-41 network. It would be apparent to those skilled in the art, the CDMA network  12  may be any variety of CDMA networks including, but not limited to cdma2000-1x and cdma2000-1xEV-DO. It would also be apparent to those skilled in the art, the GSM network  14  may be any variety of GSM network or successor network including, but not limited to General Packet Radio Services (GPRS), Universal Mobile Telecommunication System (UMTS), and Wideband-CDMA (W-CDMA). 
   The GSM network  14  comprises a GSM Core  30  and a GSM Radio Access Network  32 . The GSM Core  30  comprises a GSM Home Location Register (GSM HLR)  34 , a GSM Authentication Center (GSM AuC)  36 , a GSM Short Message Center (GSM SMSC)  38  and a GSM Gateway Mobile Switching Center (GSM GMSC)  40 . The CDMA network  12  comprises a a CDMA Home Location Register (CDMA HLR)  42 , a CDMA Authentication Center (CDMA AuC)  44 , CDMA MSC  46  and associated CDMA Radio Access Network (CDMA RAN)  48 . 
   With respect to a GSM mobile station with a subscription in a CDMA Core  20 , the GGG  16  functions as a Visitor Location Register (VLR)  50  to the GSM network  14 . With respect to a CDMA mobile station  24  with a subscription in a GSM Core  30 , the GGG  16  functions as a Visitor Location Register (Visitor LR)  52  to the CDMA network  12 . 
   Mobile stations  18 ,  20 ,  22 ,  24  do not need to have a subscription in both core infrastructures  12 ,  14  and may have a subscription in only one of the core infrastructures  12 ,  14 . 
   With respect to both the GSM mobile station with a subscription in a CDMA Core  20  and a CDMA mobile station with a subscription in a GSM Core  24 , the GGG  16  functions as a Short Message Service Center (SMSC)  54 . It would be apparent to those skilled in the art that the GGG  16  can include or communicate with the SMSC  54 . 
   Mobile stations  18 ,  20  support a GSM signaling protocol, a GSM Authentication procedure, and a GSM Short Message Service. Likewise, mobile stations  22 ,  24  support a CDMA signaling protocol, a CDMA Authentication procedure, and a CDMA Short Message Service. 
   During registration of a CDMA mobile station with a subscription in the GSM core  24 , the GGG acts as an Authentication Controller in a CDMA network, but authenticates the mobile station  24  using the GSM authentication mechanism. Likewise, during registration of a GSM mobile station with a subscription in the CDMA core  20 , the GGG acts as an Authentication Controller in a GSM network, but authenticates the mobile station  20  using the CDMA authentication mechanism. 
   The GGG acts as a message center via Short Message Service Center  54 . In a CDMA network, SMS messages are routed to and from the mobile station  24  using a CDMA SMS mechanism. In other words, in a CDMA network, GSM messages are tunneled to and from mobile station  24  using a CDMA SMS mechanism. The GSM messages are encapsulated within CDMA SMS messages. 
   Likewise, in a GSM network, SMS messages are routed to and from the mobile station  20  using a GSM SMS mechanism. In other words, in a GSSM network, CDMA messages are tunneled to and from mobile station  20  using a GSM SMS mechanism. The CDMA messages are encapsulated within GSM SMS messages. 
   An incoming call to a registered GSM subscriber  24  arrives at GSM gateway MSC (GSM GMSC)  40  in the subscriber&#39;s home GSM network  14 . The GMSC  40  interrogates the GSM LR  50  to determine the location of the subscriber  24 , which is in the CDMA network  12 . The location of the GSM subscriber  24  from the perspective of the GSM LR  50  is in the GGG  16 , which appears as a GSM VLR. When the GSM LR  50  requests routing information from the GGG  16 , the GGG  16  requests routing information from the serving CDMA LR  52  and thus the call is routed to the CDMA MSC  46 . 
   Likewise, an incoming call to a registered CDMA subscriber  20  arrives at CDMA MSC  46  in the subscriber&#39;s home CDMA network  12 . The CDMA MSC  46  interrogates the CDMA LR  52  to determine the location of the subscriber  20 , which is in the GSM network  14 . The location of the CDMA subscriber  20  from the perspective of the CDMA LR  52  is in the GGG  16 , which appears as a CDMA VLR. When the CDMA LR  50  requests routing information from the GGG  16 , the GGG  16  requests routing information from the serving GSM LR  50  and thus the call is routed to the GSM GMSC  40 . 
   The CDMA-based mobiles stations  22 ,  24  communicate with a CDMA mobile switching center (MSC)  46  using a CDMA radio access network (RAN)  48  in accordance with CDMA principles known in the art. In an embodiment, the CDMA MSC  46  is an IS-41 MSC. 
   Likewise, the GSM-based mobiles stations  18 ,  20  communicate with a GSM mobile switching center (GSM GMSC)  40  using a GSM RAN  32  in accordance with GSM principles known in the art. 
   In accordance with CDMA principles known in the art, the CDMA RAN  48  includes base stations and base station controllers. In an embodiment, CDMA RAN  24  shown in  FIG. 1  uses cdma2000, and specifically uses either cdma2000 1x, cdma2000 3x, or cdma2000 high data rate (HDR) principles. 
   In accordance with GSM principles known in the art, the GSM RAN  32  includes base stations and base station controllers. In an embodiment, GSM RAN  32  uses either GSM, GPRS, EDGE, UMTS, or W-CDMA principles. 
   The CDMA core infrastructure comprising the CDMA MSC  46  and CDMA RAN  48  can include or can access a CDMA authentication center (CDMA AUC)  44  and a CDMA home location register (CDMA HLR)  42  in accordance with CDMA principles known in the art to authenticate subscriber mobile station  22 , and to collect accounting and billing information as required by the particular CDMA core infrastructure. 
   Likewise, the GSM core  30  can include or can access a GSM authentication center (GSM AUC)  36  and a GSM home location register (GSM HLR)  34  in accordance with GSM principles known in the art to authenticate subscriber mobile station  18 , and to collect accounting and billing information as required by the particular GSM core infrastructure. 
   The CDMA MSC  46  uses the GGG  16  to communicate with the GSM network  14 . The GSM network  14  can include or can access a GSM authentication center  36  and a GSM home location register (HLR)  34  in accordance with GSM principles known in the art to authenticate subscriber mobile station  24  and to collect accounting and billing information as required by the particular GSM core  30 . 
   Likewise, GSM GMSC  40  uses the GGG  16  to communicate with the CDMA network  12 . The CDMA network  12  can include or can access a CDMA authentication center  44  and a CDMA home location register (HLR)  42  in accordance with CDMA principles known in the art to authenticate subscriber mobile station  20  and to collect accounting and billing information as required by the particular CDMA network  12 . 
   Both the GSM core  30  and the CDMA core infrastructure can communicate with a network such as a public switched telephone network (PSTN) and/or an Internet Protocol (IP) network. 
   With respect to a CDMA mobile station  24  with a subscription in a GSM Core  30 , the GGG  16  functions as a VLR  50  to the GSM network  14 . The GGG meets GSM protocol requirements for a VLR  50 . The GGG interacts with GSM core network elements such as GSM HLR  34  and GSM SMSC  38  according to GSM specifications, except that the GGG  16  routes incoming calls to the CDMA network  12 . The GSM LR  50  also performs a location update with the GSM network  14  when the mobile station registers in the CDMA network  12 . In this sense, the GGG acts as a VLR to the whole CDMA network  12 . 
   With respect to a GSM mobile station  20  with a subscription in a CDMA network  12 , the GGG  16  functions as a VLR  52  to the CDMA network  14 . The GGG meets CDMA protocol requirements for a VLR  52 . The GGG interacts with CDMA core network elements such as CDMA HLR  42  and CDMA MSC  46  according to CDMA specifications, except that the GGG  16  routes incoming calls to the CDMA network  12 . The CDMA LR  52  also performs a location update with the CDMA network  12  when the mobile station registers in the GSM network  14 . In this sense, the GGG acts as a VLR to the whole GSM network  14 . 
   When a mobile station that is in the CDMA network  12  is called from the GSM network  14 , the call is routed to the CDMA LR  52  in the GGG  16  per standard specifications. The GGG  16  routes the call to the CDMA network  12 . The CDMA network  12  eventually routes the call to the CDMA MSC  46  serving the mobile station. Similarly, if an SMS is routed to the CDMA network  12  from the GSM network  14 , the GGG  16  routes the message to a message center (not shown) within the CDMA network  12 . 
   When a mobile station that is in the GSM network  14  is called from the CDMA network  12 , the call is routed to the GSM LR  50  in the GGG  16  per standard specifications. The GGG  16  routes the call to the GSM network  14 . The GSM network  14  eventually routes the call to the GSM GMSC  40  serving the mobile station. Similarly, if an SMS is routed to the GSM network  10  from the CDMA network  12 , the GGG  16  routes the message to a GSM SMSC  38  within the GSM network  14 . 
   When a mobile station registers with the CDMA network  12 , the CDMA network  12  sends a location update indication to the GSM network  14 . The GSM LR  50  then performs a location update as per standard specifications with the GSM core network  14 . 
   When a mobile station registers with the GSM network  14 , the GSM network  14  sends a location update indication to the CDMA network  12 . The CDMA LR  52  then performs a location update as per standard specifications with the CDMA network  12 . 
   With respect to a CDMA mobile station  24  with a subscription in a GSM Core  30 , the GGG  16  acts as an HLR  52  in the CDMA network  12 . The CDMA LR  52  shall meet HLR protocol requirements for GSM to CDMA roaming. An important piece of information that the HLR  52  maintains is the address of the CDMA MSC  46  serving the mobile station  24 . When the GSM LR  50  in the GGG  16  routes a call to the CDMA side  12 , the CDMA LR  52  will further route it to the serving MSC  46 . 
   With respect to a GSM mobile station  20  with a subscription in a CDMA network  12 , the GGG  16  acts as an HLR  50  in the GSM network  14 . The GSM LR  50  shall meet HLR protocol requirements for CDMA to GSM roaming. An important piece of information that the HER maintains is the address of the GSM GMSC  40  serving the mobile station  20 . When the CDMA LR  52  in the GGG  16  routes a call to the GSM side  14 , the GSM LR  50  will further route it to the serving MSC  40 . 
   The GGG acts as an Authentication Controller (AUC) in the CDMA network for GSM subscribers  24 . The AUC  44  in a CDMA network  12  is responsible for authenticating a mobile station and permitting/denying access to network resources. The AUC function in the GGG does not call for A-key provisioning at the GGG or the MS. Instead the GGG uses the GSM authentication credentials and the GSM authentication method via GSM signaling to authenticate the mobile station  24 . The GGG responds to valid messages that can be received by a CDMA AUC  44 . 
   The GGG acts as an Authentication Controller (AUC) in the GSM network for CDMA subscribers  20 . The AUC  36  in a CDMA network  14  is responsible for authenticating a mobile station and permitting/denying access to network resources. The AUC function in the GGG does not call for A-key provisioning at the GGG or the MS. Instead the GGG uses the CDMA authentication credentials and the CDMA authentication method via CDMA signaling to authenticate the mobile station  20 . The GGG responds to valid messages that can be received by a GSM AUC  36 . 
   The GGG  16  acts as a Message Center (MC) in the CDMA network  12  and routes SMS messages between the CDMA mobile station  24  and GSM GMSC  40  using a GSM SMS mechanism. 
   Likewise, the GGG  16  acts as a Message Center (MC) in the GSM network  14  and routes SMS messages between the GSM mobile station  20  and CDMA MSC  46  using a CDMA SMS mechanism. 
   The CDMA MS  24  is required to have a valid identity in the CDMA network. If this identity is different from the GSM International Mobile Subscriber Identity (IMSI) (i.e., if the CDMA network does not use true IMSI), then the GGG provides a mapping between the CDMA identity and the GSM IMSI. It would be apparent to those skilled in the art that any technique/method known in the art to uniquely identify the mobile station  24  may be used. 
   The GSM MS  20  is required to have a valid identity in the GSM network. In an embodiment, this identity is a GSM IMSI (i.e., if the CDMA network does not use true IMSI). If the identity in the GSM network is different from the identity in a CDMA network, then the GGG provides a mapping between the GSM identity and the CDMA identity. It would be apparent to those skilled in the art that any technique/method known in the art to uniquely identify the mobile station  20  may be used. 
   In a non-limiting embodiment, mobile stations  18 ,  20 , are mobile telephones made by Kyocera, Samsung, or other manufacturer that use GSM principles and GSM over-the-air (OTA) communication air interfaces. In a non-limiting embodiment, mobile stations  22 ,  24 , are mobile telephones made by Kyocera, Samsung, or other manufacturer that use CDMA principles and CDMA over-the-air (OTA) communication air interfaces. The present invention, however, applies to other mobile stations such as laptop computers, wireless handsets or telephones, data transceivers, or paging and position determination receivers. The mobile stations can be hand-held or portable as in vehicle-mounted (including cars, trucks, boats, planes, trains), as desired. However, while wireless communication devices are generally viewed as being mobile, it is to be understood that the present invention can be applied to “fixed” units in some implementations. Also, the present invention applies to data modules or modems used to transfer voice and/or data information including digitized video information, and may communicate with other devices using wired or wireless links. Further, commands might be used to cause modems or modules to work in a predetermined coordinated or associated manner to transfer information over multiple communication channels. Wireless communication devices are also sometimes referred to as user terminals, mobile stations, mobile units, subscriber units, mobile radios or radiotelephones, wireless units, or simply as “users” and “mobiles” in some communication systems. 
     FIGS. 2   a  and  2   b  shows a flowchart for authenticating a CDMA mobile station  24  with a subscription in a GSM network  14  in accordance with an embodiment. In step  202 , mobile station  24  (MS) roams into a CDMA area and the flow of control proceeds to step  204 . In step  204 , the mobile station  24  initiates a registration system access to a CDMA MSC  46  via a CDMA RAN  48  and the flow of control proceeds to step  206 . 
   The registration system access is a message to the CDMA MSC  46  via the CDMA RAN  48 , the message including an identity of the mobile station  24 . In an embodiment, the identity of the mobile station  24  may be provided by the SIM  28 . In an embodiment, the identity of the mobile station  24  is an IMSI. In an embodiment, the identity of the mobile station  24  is a Mobile Identification Number (MIN). 
   In step  206 , the CDMA MSC  46  determines, based on the mobile station identity, whether the mobile station  24  is a GSM subscriber. In an embodiment, wherein the identity of the mobile station  24  is an IMSI, the MSC  46  can make this determination because the IMSI contains, among other information, a code representing the country and network in which the mobile station has a subscription. 
   In the event that the CDMA-subscribing mobile station  22  is the mobile station under test, the flow of control proceeds to step  208 . In step  208 , the mobile station  22  is authenticated using CDMA principles by the CDMA core infrastructure, using the CDMA HLR  42  and CDMA AUC  44 . 
   In the event that the CDMA mobile station  24  with a subscription in the GSM network  14  is the mobile station under test, the flow of control proceeds to step  210 . In step  210 , the CDMA MSC  46  accesses the GGG  16  by sending an Authentication Request to the CDMA LR  52  in the GGG  16  and the flow of control proceeds to step  212  in accordance with an embodiment. In another embodiment, the flow of control proceeds to step  214 . 
   In an embodiment, the identity of the mobile station  24  is sent to the CDMA LR  52  as part of the Authentication Request. Alternatively, the identity of the mobile station  24  is sent to the CDMA LR  52  in addition to the Authentication Request. 
   In an embodiment, the Authentication Request may include parameters MIN, ESN and COUNT. ESN is an electronic serial number. COUNT represents a count of a predetermined event that is a mutually agreed upon event between the GGG  16  and mobile station  24 . Each time the predetermined event occurs, the mobile station  24  and the GGG  16  updates COUNT for the particular mobile station  24 . In an embodiment, the GGG  16  shares the updating of COUNT with a node that interacts with the GGG  16 . By sharing the update function with another node, the message traffic between the GGG  16  and the other node may be reduced. For example, if the GGG  16  shares the function of updating COUNT with the CDMA MSC  46 , then the message traffic between the GGG  16  and the CDMA MSC  46  may be reduced. 
   In an embodiment, COUNT represents the number of times a mobile station  24  attempts to access the GSM network  14 . Each time the mobile station  24  accesses the GSM network, the GGG updates a COUNT for the particular mobile station  24 . The mobile station  24  also updates its own COUNT for the number of times it accesses the GSM network  14 . The GGG  16  stores the value of the ESN. In another embodiment, COUNT represents a number of requests for authentication by the mobile station. It would be apparent to those skilled in the art that there are many events that can be counted, which the mobile station  24  and GGG  16  can count. 
   ### 
   In step  212 , the GGG  16  compares the value of COUNT to a count value in a GGG database. If the value of COUNT is equal to the count value in the GGG database, then the flow of control proceeds to step  214 . If the value of COUNT is not equal to the count value in the GGG database, then the flow of control proceeds to step  216 . It would be apparent to those skilled in the art that depending on an application, a variety of criteria may be applied to determine whether an Authentication Request is honored. 
   In step  214 , an Authentication Request Return Result (ARRR) is set to true and the flow of control proceeds to step  218 . The Authentication Request Return Result message indicates the result of the Authentication Request. 
   In step  216 , the Authentication Request Return Result is set to false and the flow of control proceeds to step  220 . 
   In response to the Authentication Request Return Result being true, the GGG  16  accesses the GSM network  14  and obtains necessary authentication information from the GSM HLR  34  and GSM AuC  36 . In step  218 , the GGG  16  looks up the MIN in its database to obtain a corresponding GSM IMSI and accesses the GSM network  14  by sending a GSM HLR authentication message with the IMSI of the mobile station  24  to the GSM HLR/AuC  34 ,  36 , in accordance with an embodiment. The flow of control proceeds to step  220 . 
   Method steps can be interchanged without departing from the scope of the invention. Thus, it would be apparent to those skilled in the art that step  218  does not have to be performed before step  220 . 
   In step  220 , the GGG  16  sends the Authentication Request Return Result to the CDMA MSC  46  and the flow of control proceeds to step  222 . In step  222 , the Authentication Request Return Result is tested. If the Authentication Request Return Result is true, then in step  224  the GGG  16  starts a timer, T REG and the flow of control proceeds to step  226 . 
   If the Authentication Request Return Result is false, then the flow of control proceeds to step  228 . In step  228 ., the CDMA MSC  46  sends a mobile station authentication message to the mobile station  24  indicating the mobile station  24  is not authenticated. It would be apparent to those skilled in the art that the mobile station may reattempt authentication depending on the application. 
   The GGG includes a logic unit (not shown) to execute program logic. It would be apparent to those skilled in the art that the logic unit may include a general purpose processor, a special-purpose processor, and/or firmware. 
   In step  226 , the CDMA MSC  46  upon receiving an Authentication Request Return Result indicating successful authentication, sends a Registration Notification to the CDMA LR  52  in the GGG  16 . The flow of control proceeds to step  230 . 
   In step  230 , a check is made to determine whether the GGG  16  received the Registration Notification before T REG expired. If the GGG  16  received the Registration Notification before T REG expired, then the flow of control proceeds to step  232 , otherwise the flow of control proceeds to step  234 . In step  232 , Registration Notification Return Result is set to indicate T REG did not expire and the flow of control proceeds to step  236 . In step  234 , Registration Notification Return Result is set to indicate T REG expired and the flow of control proceeds to step  236 . 
   In step  236 , the GGG  16  responds to the Registration Notification with a Registration Notification Return Result indicating whether T REG expired. The Registration Notification Return Result is sent from the GGG  16  to the CDMA MSC  46 . 
   In an embodiment, the GGG  16  sends a message with or within the Registration Notification Return Result indicating SMS only mode/status. “SMS only” means the mobile station  24  sends and receives only SMS messages, not data and/or voice messages. The flow of control proceeds to step  238 . 
   In step  238 , the CDMA MSC  46  sends a Registration Accept message to the mobile station  24  upon receiving the Registration Notification Return Result. Like the Registration Notification Return Result, the Registration Accept message indicates whether T REG expired. The flow of control proceeds to step  240 . 
   In step  240 , the mobile station  24  determines whether the Registration Accept message indicates an accepted registration, i.e., T REG did not expire. If T REG expired, then the flow of control proceeds to step  242 , otherwise the flow of control proceeds to step  244 . 
   In step  242 , the mobile station  24  may or may not reattempt registration. It would be apparent to those skilled in the art that depending on a mobile station application, the mobile station may or may not reattempt registration. 
   Method steps can be interchanged without departing from the scope of the invention. Thus, it would be apparent to those skilled in the art that step  244  does not have to be performed after step  242 . 
   Step  244  only has to be executed after the GSM HLR authentication message has been sent to the GSM BLR/AuC  34 ,  36  of step  218 . In step  244 , the GSM HLR/AuC  34 ,  36  sends a GGG authentication message including authentication parameters to the GGG  16  and the flow of control proceeds to step  246 . 
   After the GGG  16  successfully sends the Registration Notification Return Result to the CDMA MSC  46  and receives the GGG authentication message from the GSM HLR/AuC  34 ,  36 , the GGG  16  sends a GSM authentication request message to the CDMA MSC  46  in step  246 . The flow of control proceeds to step  248 . In step  248 , the CDMA MSC  46  forwards the GSM authentication request message to the mobile station  24  and the flow of control proceeds to step  250 . 
   In an embodiment, an application may have more criteria for authenticating mobile stations apart from the criteria applied to the original Authentication Request of step  210 . Thus, in an embodiment, the CDMA MSC  46  sends a second authentication request (not shown) to the GGG  16  and the GGG  16  responds to the second authentication request (not shown). 
   In step  250 , the mobile station  24  responds to the GSM authentication request message by determining authentication parameters such as an encryption key using a GSM authentication method and sending an authentication response including the authentication parameters to the CDMA MSC  46 . In an embodiment, the authentication response is sent using the IS-637 SMS transport. The flow of control proceeds to step  252 . 
   In step  252 , the CDMA MSC  46  forwards the authentication response to the GGG  16  and the GGG  16  validates that the authentication parameters by matching the authentication parameters to values received from the GSM HLR/AuC  34 ,  36  in step  244 . The flow of control proceeds to step  254 . 
   In step  254 , the GGG  16  sends an update location message to the GSM HLR  34  to update the location of the mobile station  24  and the flow of control proceeds to step  256 . In step  256 , the GSM HLR  34  sends GSM subscriber profile data of the mobile station  24  to the GSM LR  50  in the GGG  16 . The flow of control proceeds to step  258 . 
   In step  258 , the GGG  16  maps the GSM subscriber profile data to a CDMA subscriber profile and sends the CMDA profile data in a Qualification Directive to the CDMA MSC  46  and the flow of control proceeds to step  260 . The Qualification Directive indicates that the mobile station  24  is qualified, i.e., authorized to communicate with the GSM network  14 . If the mobile station  24  is not qualified, then mobile station  24  is not authorized to communicate with the GSM network  14  (not shown). In an embodiment, the GGG  16  indicates to the CDMA MSC  46  “full profile,” which in turn is forwarded to the mobile station  24  and indicates to the mobile station  24  that the mobile station  24  can send and receive without being limited to SMS messages. 
   In step  260 , the CDMA MSC  46  responds to the Qualification Directive and sends a Qualification Directive Response to the CDMA LR  52  and the flow of control proceeds to step  262 . 
   In step  262 , responsive to the GSM LR  50  receiving the GSM subscriber profile data, the GGG  16  sends a GSM subscriber profile data response to the GSM HLIWAuC  34 ,  36 . 
   In step  264 , responsive to the GSM HLR  34  receiving the update location message from the GGG  16  in step  254 , the GSM HLR  34  responds to the update location message and sends a update location message response to the GSM LR  50 , the update location message response indicating that the location of the mobile station  24  has been updated at the GSM LR  50 . 
   While the particular AUTHENTICATING BETWEEN A CDMA NETWORK AND A GSM NETWORK as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and is thus representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more”. All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited as a “step” instead of an “act”. 
   Method steps can be interchanged without departing from the scope of the invention.