Abstract:
The present invention provides a service node to facilitate the integration of cellular and packet networks. In particular, the service node acts as a proxy for packet-based communications over a packet network for a packet communication client, and also emulates a call routing entity associated with a cellular network. In select embodiments, the call routing entity emulated by the service node may be a visited mobile switching center, home mobile switching center, or a home location register. In operation, calls being processed in the cellular network may be processed in part by the service node, which is emulating a particular call routing entity. For calls involving the cellular network that are ultimately terminated on the packet network, the service node supports efficient call processing or handling, depending on the call routing entity being emulated.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to communications, and in particular to integrating packet-based communication clients with traditional cellular networks.  
       BACKGROUND OF THE INVENTION  
       [0002]     The evolution of mobile communications had led to an extensive cellular infrastructure, which is integrally connected to the Public Switched Telephone Network (PSTN). Traditionally, cellular networks and the PSTN have supported voice communications, while packet networks have been predominantly used for data communications. In recent years, packet networks have been used to support voice communications. Since cellular networks and the PSTN dominate voice communications, there is a need to integrate packet networks, cellular networks, and the PSTN for voice communications, especially for evolving packet-based communication clients. There is a further need to allow packet-based communication clients to readily make and receive calls supported in part over the PSTN or cellular networks in an efficient manner.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention provides a service node to facilitate the integration of cellular and packet networks. In particular, the service node acts as a proxy for packet-based communications over a packet network for a packet communication client, and also emulates a call routing entity associated with a cellular network. In select embodiments, the call routing entity emulated by the service node may be a visited mobile switching center, home mobile switching center, or a home location register. In operation, calls being processed in the cellular network may be processed in part by the service node, which is emulating a particular call routing entity. The cellular network need not be aware that the service node is not an actual home mobile switching center, visited mobile switching center, or home location register. For calls involving the cellular network that are ultimately terminated on the packet network, the service node supports efficient call processing or handling, depending on the call routing entity being emulated.  
         [0004]     In one embodiment, the service node acts as a proxy for packet communications for a packet communication client, as well as emulates a visited mobile switching center. To the cellular network, the service node will appear as a visited mobile switching center that is supporting the packet communication client. Although a packet-based session will be used to establish a part of the call to the packet communication client, the cellular network will interact with the service node as if it were a traditional visited mobile switching center. Similarly, the service node may emulate a home mobile switching center, wherein from the cellular network&#39;s perspective the service node appears as a home mobile switching center by which the packet communication client or other mobile terminal may be supported. As such, incoming calls are initially directed to the home mobile switching center, which may interact with a home location register to determine how to route the incoming call or make decisions on call routing based on whether or not the packet communication client is registered with the home mobile switching center. In the latter case, interaction with the home location register is not necessary, but may be provided to assist in call processing.  
         [0005]     In yet another embodiment, the service node may act as a proxy for the packet communication client, as well as acting as a home location register for the cellular network. As such, traditional home location register operation may be provided, in which interaction with various visited and home mobile switching centers is provided. In addition, packet-based communication clients may directly register with the service node, such that the service node, acting in a home location register capacity, may control where and how calls are routed to mobile terminals as well as to packet-based communication clients. Notably, the packet-based communication clients may be multimode devices in which traditional cellular communications as well as packet-based communications may be facilitated. As such, one device may act as a mobile terminal and a packet-based communication client, and therefore communicate over a cellular network in a traditional fashion and over a packet network in a packet-based fashion. Packet communications may be facilitated using wired or wireless technologies.  
         [0006]     Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0007]     The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention.  
         [0008]      FIG. 1  is a traditional cellular communication environment, and illustrates an exemplary registration and call setup sequence.  
         [0009]      FIG. 2  is a communication environment in which a service node associated with a packet network emulates a visiting mobile switching center of a cellular network according to one embodiment of the present invention.  
         [0010]      FIGS. 3A and 3B  illustrate a communication environment in which a service node associated with a packet network emulates a home mobile switching center of a cellular network according to a second embodiment of the present invention.  
         [0011]      FIG. 4  is a communication environment in which a service node associated with a packet network emulates a home location register of a cellular network according to a third embodiment of the present invention.  
         [0012]      FIG. 5  is a block representation of a service node according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.  
         [0014]     The present invention allows a service node associated with a packet network to emulate a traditional entity of a cellular network, such as a mobile switching center or home location register, to allow a packet-based communication client to establish calls over the cellular network, and thus over the PSTN as well. Prior to delving into the details of the present invention, an overview of a basic registration and call setup process in a cellular environment is illustrated.  
         [0015]     With reference to  FIG. 1 , a communication environment  10  is shown centered about a traditional cellular network  12 . In traditional fashion, the cellular network  12  interacts with the PSTN  14 . Calls between a mobile terminal  16  supported by the cellular network  12  and a telephone terminal  18 , which is supported by the PSTN  14 , may be established over the PSTN  14  and the cellular network  12 . Generally, a mobile terminal  16  is associated with a home mobile switching center (HMSC)  20 , which acts as a gateway for all communications terminating to the mobile terminal&#39;s telephone number. When the mobile terminal  16  is outside of the radio access network specifically associated with the HMSC  20 , cellular communications will be established through a currently supporting visiting MSC (VMSC)  22  and an associated base station  24 , which provides a wireless interface to the mobile terminal  16 .  
         [0016]     When a mobile terminal  16  is supported by a VMSC  22 , a registration message is sent to a home location register (HLR)  26  (step  100 ). The registration message provides the HLR  26  with sufficient information to identify the mobile terminal  16  and the VMSC  22  currently supporting the mobile terminal  16 , such that calls intended for the mobile terminal  16  that are received at the HMSC  20  can be properly routed to the mobile terminal  16  through the supporting VMSC  22 . Thus, when a call is directed to the mobile terminal  16  from the telephone terminal  18 , a call setup request is sent to the HMSC  20  (step  102 ). If the mobile terminal  16  is not being supported by the HMSC  20 , the HMSC  20  will send a location query to the HLR  26  (step  104 ) to retrieve information identifying the VMSC  22  currently supporting the mobile terminal  16 . The HLR  26  will respond with the requisite information (step  106 ), and the HMSC  20  will forward the call request to the VMSC  22  currently supporting the mobile terminal  16  (step  108 ). At this point, the HMSC  20  and VMSC  22  can cooperate with one another and any other necessary network entities to establish a bearer path between the telephone terminal  18  and the mobile terminal  16  through the PSTN  14 , HMSC  20 , and VMSC  22  of the cellular network  12  (step  110 ). Notably, other variations such as directing a call to a voicemail server in the event the terminal  16  is not currently registered may be supported.  
         [0017]     Turning now to  FIG. 2 , a first embodiment of the present invention is illustrated. In this embodiment, a packet network  28  is coupled to the cellular network  12  through an appropriate gateway  30 , which will provide the necessary signal conversion to facilitate communications between the cellular network  12  and the packet network  28 . The packet network  28  will support a packet-based communication client  32 , which may have a connection to the packet network  28  through a wired or wireless interface. In this embodiment, a service node  34  is configured to act as a proxy for communications involving the packet-based communication client  32 . Further, the service node  34  is configured to emulate a VMSC on the cellular network  12 . As such, the packet-based communication client  32  will appear as if it is a mobile terminal being supported by the VMSC emulated by the service node  34 . Thus, the cellular network  12  does not have to realize that the packet-based communication client  32  is not a typical mobile terminal  16 . As such, the packet-based communication client  32  will register with the service node  34  upon being able to communicate with the packet network  28  (step  200 ). The service node  34  will recognize the registration and, acting as a VMSC, register the packet-based communication client  32  with the HLR  26  (step  202 ) as if the packet-based communication client  32  were a mobile terminal supported by a typical VMSC.  
         [0018]     When a call is initiated from the telephone terminal  18 , a call setup request is sent through the PSTN  14  to the HMSC  20  of the cellular network  12  (step  204 ). The HMSC  20  will recognize that the packet-based communication client  32  is not supported by the HMSC  20 , and thus will send a location query to the HLR  26  (step  206 ). The HLR  26  will then respond by providing information bearing on how to route the call to the packet-based communication client  32  (step  208 ). In this case, the routing information will include a directory number or address for the gateway  30  and associated with the service node  34 , as it is emulating a VSMC. Thus, the call setup request will be routed to the service node  34  through the gateway  30  (step  210 ). Upon receipt of the call setup request, the service node  34  will route the call to the packet-based communication client  32  (step  212 ). At this point, a bearer path is established between the telephone terminal  18  and the packet-based communication client  32  through the PSTN  14 , the HMSC  20  of the cellular network  12 , the gateway  30 , and the packet network  28  (step  214 ). Notably, a circuit-switched session is established between the gateway  30  and the telephone terminal  18 , and a packet session is established between the gateway  30  and the packet-based communication client  32 .  
         [0019]     Those skilled in the art will recognize that additional messaging will take place throughout the various networks to establish the circuit-switched and packet-based sessions. In one embodiment, the Session Initiation Protocol (SIP) may be used for the call signaling taking place over the packet network  28  between the gateway  30 , service node  34 , and packet-based communication client  32 . The service node  34  in a SIP embodiment will act as a SIP proxy for establishing packet-based sessions, as well as emulate a VMSC in cooperation with the gateway  30 . Those skilled in the art will recognize other protocols capable of being implemented according to the concepts of the present invention.  
         [0020]     Turning now to  FIGS. 3A and 3B , the service node  34  in this embodiment will emulate an HMSC of the cellular network  12 . With particular reference to  FIG. 3A , assume that either the mobile terminal  16  or the packet-based communication client  32  can use a common ID or be associated with a common directory number. Notably, a single device may be associated with multiple IDs and directory numbers. As such, various rules may be established and implemented by the service node  34  to determine the device to which incoming calls are routed. Assume that the mobile terminal  16  is roaming and is being supported by the VMSC  22 . As such, a registration message will be sent to the HLR  26  to register the mobile terminal  16  in association with the VMSC  22  (step  300 ). Also assume that a packet-based communication client  32  is capable of communicating over the packet network  28 , and will thus register with the service node  34  (step  302 ). The service node  34  is also associated directly or indirectly with the cellular network  12 , and appears as an HMSC for the mobile terminal  16  as well as for the packet-based communication client  32 . As such, when an incoming call is intended for either the mobile terminal  16  or the packet-based communication client  32 , a call request will be routed through the cellular network  12  or PSTN to the service node  34  as if it were an HMSC (step  304 ). The service node  34  will determine where the call should be routed. Such determination may be as simple as always preferring the packet client whenever it is reachable or may use more complex rules including time of day, presence and other criteria. In this example the call should be routed to the packet-based communication client  32 . As such, the service node  34  will send a call request, such as a SIP Invite message, to the packet-based communication client  32  (step  306 ), and a bearer path is established between the telephone terminal  18  and the packet-based communication client  32  through the PSTN  14 , cellular network  12 , gateway  30 , and packet network  28  (step  308 ). Again, additional call setup messages will be provided in traditional fashion to establish a circuit-switched connection between the telephone terminal  18  and the gateway  30 , as well as a packet session between the gateway  30  and the packet-based communication client  32 .  
         [0021]     Turning now to  FIG. 3B , assume the packet-based communication client  32  is initially registered with the service node  34  (step  310 ), and the mobile terminal  16  is registered in association with the VMSC  22  and HLR  26  (step  312 ). When a call request for the mobile terminal  16 , the packet-based communication client  32 , or a combination thereof is routed to the service node  34  (step  314 ), which is acting as an HMSC for either the mobile terminal  16  or the packet-based communication client  32 , the service node  34  may access the HLR  26  to obtain the relative location of the mobile terminal  16 . In this example, assume a location request for the mobile terminal  16  is sent to the HLR  26  (step  316 ), which responds with information identifying the VMSC  22  as the MSC supporting the mobile terminal  16  (step  318 ). As such, the service node  34  may route the incoming call to the VMSC  22  (step  320 ), wherein a bearer path is established through the cellular network  12  between the telephone terminal  18  and the mobile terminal  16  through the VMSC  22  (step  322 ). As such, the service node  34  may determine whether or not to access the HLR  26  to obtain call routing information or general information to assist in determining how and where to route an incoming call intended for one or more communication clients, which may be mobile terminals or packet-based communication clients. In one embodiment, the service node  34  will route the call to packet-based communication clients that are registered with the service node  34 , and if there are no such communication clients, it will access the HLR  26  to obtain routing information and then route the call accordingly.  
         [0022]     Turning now to  FIG. 4 , the service node  34  may act as an HLR and allow registration of information related to the mobile terminal  16  from traditional VSMCs  22  (step  400 ), as well the registration of packet-based communication clients  32  over the packet network  28  (step  402 ). As such, HMSCs (not illustrated) may access the service node  34  to determine where and how to route an incoming call. The service node  34 , when it is acting as an HLR, may provide call routing rules based on service provider or subscriber preferences. For example, the service node  34  may be configured to direct an HMSC  20  to route an incoming call to a client contact number associated with the gateway  30  when the packet-based communication client  32  is capable of communicating with the packet network  28  and has registered as such with the service node  34 . The gateway  30  may alone or in association with other entities establish a circuit-switched call with the caller&#39;s device, and a packet session with the packet-based communication client  32 . Thus, the service node  34  may act as a SIP proxy in a SIP environment, as well as an HLR for the cellular network  12 .  
         [0023]     Turning now to  FIG. 5 , a block representation of a service node  34  is illustrated. The service node  34  may include a control system  36  having sufficient memory  38  to store the requisite software  40  to provide operation as described above. The memory  38  will also store the necessary data  42  required for operation. The control system  36  will be associated with one or more communication interfaces  44  to facilitate communication over the packet network  28  and perhaps the cellular network  12  in select embodiments.  
         [0024]     Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.