MANAGING SIMULTANEOUS ACCESS TO COMMUNICATIONS SERVICES FROM MULTIPLE COMMUNICATIONS NETWORKS

FIELD

[0001] The invention described herein relates to network management, In particular, the invention described herein relates to the provision of communications services to communications devices over multiple communications networks.

BACKGROUND

[0002] In a wireless communications network, the network maintains a subscriber profile for the provision of communications services for each wireless subscriber, The subscriber profile identifies the communications services to which the subscriber is authorized, and includes an identifier that is uniquely associated with the mobile terminal of the subscriber,

[0003] Many mobile stations are configured to receive communications services over multiple communications networks. However, since the contents of a subscriber profile for a given subscriber varies with the associated communications network, the unique identifier that is used to identify the mobile terminal in one communications network might not be associated with the same mobile terminal in another communications network. Therefore, the mobile terminal will be considered by each communications network to have a separate and distinct wireless subscriber.

SUMMARY

[0004] In one aspect, this disclosure relates to a method of providing communications services. The method involves selecting, in response to an incoming communication intended for a communications service subscriber, a communications network from a plurality of communications networks in accordance with a subscriber profile associated with the communications service subscriber. The subscriber profile defines a communications network preference for receipt of communications services from the communications networks. Termination of the incoming communication to the

communications service subscriber is facilitated via the selected communications network.

[0005] In another aspect, this disclosure relates to a computer-readable medium that carries computer processing instructions for execution by a computer. The processing instructions, when executed, causes the computer to perform the following method:

(1) in response to an incoming communication intended for a communications service subscriber, select a communications network from a plurality of communications networks in accordance with a subscriber profile associated with the communications service subscriber, the subscriber profile defining a communications network preference for receipt of communications services from the communications networks; and

(2) facilitate termination of the incoming communication to the communications service subscriber via the selected communications network.

[0006] The method may also involve, prior to the network selecting, facilitating the simultaneous registration of a communications device . (associated with the communications service subscriber) at one of the communications networks and at an other of the communications networks for the provision of communication services to the communications device. This simultaneous registration may involve facilitating the registration of the communications device at the other communications network after receiving a communication service request requesting the registration of the communications device at the one communications network.

[0007] The termination may be facilitated by redirecting the incoming communication to the communications device via the one communications network after the incoming communication is received over the other communications network.

[0008] In yet another aspect, this disclosure relates to a multi-access subscription server. The multi-access subscription server comprises a subscriber profile database, and a network selector. The multi-access subscription server may also comprise service request processor.

[0009] The subscriber profile database may comprise a subscriber profile that is associated with a communications service subscriber. The subscriber profile defines a communications network preference for receipt of communications services from a plurality of communications networks.

[0010] The network selector communicates with the subscriber profile database, and may be configured to select, in response to an incoming communication intended for the Communications service subscriber, a communications network from the plurality of communications networks in accordance with the subscriber profile that is associated with the communications service subscriber. The network selector may also be configured to facilitate termination of the incoming communication to the communications service subscriber via the selected communications network,

[0011] The service request processor also communicates with the subscriber profile database, and may be configured to facilitate simultaneous registration of a communications device at one of the communications networks and at an other of the communications networks for the provision of communication services to the communications device by the one communications networks and the other communications network. The service request processor may be configured to facilitate the simultaneous registration by initiating the registration of the communications device at the other communications network after receiving a communication service request requesting the registration of the communications device at the one communications network.

[0012] The service request processor may facilitate the termination by redirecting the incoming communication from the other communications network to the one communications network.

[0013] In yet another aspect, this disclosure relates to a method of providing access to communications services. The method involves facilitating registration of a communications device at one of a plurality of communications networks for the

provision of communication services to the communications device by the communications network. The communications device is associated with a communications service subscriber, In accordance with a subscriber profile that is associated with the communications service subscriber, registration of the communications device is facilitated at an other one of the communications networks for the provision of communication services to the communications device by the other communications network. The registration at the other communications network is facilitated substantially simultaneously with the registration at the one communications network..

[0014] In yet another aspect, this disclosure relates to a computer-readable medium that carries computer processing instructions for execution by a computer. The processing instructions, when executed, causes the computer to perform the following method:

(1) facilitate registration of a communications device at one of a plurality of communications networks for the provision of communication services to the communications device by the communications network, the communications device being associated with a communications service subscriber, and

(2) in accordance with a subscriber profile that is associated with the communications service subscriber, facilitate registration of the communications device at an other one of the communications networks for the provision of communication services to the communications device by the other communications network, the registration at the other communications network being substantially simultaneous with the registration at the one communications network..

[0015] In one implementation, the communications networks are incompatible with each other. For instance, one of the communications networks could comprise a circuit- switched network, and another one of the communications networks could comprise a packet-switched network. One of the communications networks could comprise a wireless cellular communications network, and another one of the communications networks could comprise a local area network.

[0016] The communications device might be configured for direct communication with one of the communications networks and with the other communication network. Alternately, the communications device might be configured for direct communication with only one of the communications networks.

[0017] The communication service request may be received at a subscription server of the one communications network. The simultaneous registering may involve registering the subscription server as a communications device on the another communications network.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view of one example embodiment of a communicationscommunications system, comprising a GSM network and a pre-IMS SIP network;

Fig. 2a is a signal diagram that depicts the message traffic when a mobile station registers with the GSM network;

Fig. 2 is a signal diagram that depicts the message traffic when a mobile station registers with the pre-IMS SIP network;

Figs. 3 and 4 are signal diagrams that depict the message traffic when the communicationscommunications system receives a terminating call via the GMSC;

Figs. 5 and 6 are signal diagrams that depict the message traffic when the communicationscommunications system receives a terminating call via the Softswitch;

Fig. 7 is a schematic view of a second example embodiment of a communicationscommunications system, comprising a GSM network and an SEP/IMS network;

Fig. 8 is a signal diagram that depicts the message traffic when the a mobile station registers with the GSM network and the SIP/IMS network of the communicationscommunications system of Fig. 7; and

Fig. 9 is a signal diagram that depicts the message traffic when the communicationscommunications system of Fig. 7 receives a teπninating call via the Softswitch.

DETAILED DESCRIPTION

COMMUNICAηONSCOMMUMCATIONS SYSTEM 100

[0019] Turning to Fig. 1, a mobile station 10 is configured to receive communication services from a communicationscommunications system 100. The mobile station 10 is a wireless commuiu ^' cationscommunications device, and may be implemented as a wireless telephone or as a wireless personal digital assistant having voice and/or data communication capabilities. In this embodiment, the mobile station 10 is a multi-mode ^■ wireless communications device that is configured for simultaneous use with a plurality of wireless communications networks. An example in which the mobile station 10 is a single-mode wireless communications device will be discussed below, with reference to Figs. 7 to 9. However, as will be explained, the communicationscommunications system 100 may provide communication services to a wireline device, in addition to, or instead of, the mobile station 10.

[0020] The communications networks may be compatible or "incompatible" with each other. As used herein, communications networks are "incompatible" if the communications protocol that is implemented in one of the networks is not recognized in the other networks, or if the requirements for delivery of communicationscommunications services to the mobile station 10 over one of the networks are different than the requirements of the other networks.

[0021] For instance^ the mobile station 10 might be configured to receive communicationscommunications services from a circuit-switched network and a packet- switched network. The mobile station 10 might be configured to receive communicationscommunications services via a long-range cellular communications protocol, and a short-range high speed communications protocol. In the embodiment of Fig. 1, the mobile station 10 is configured to receive communicationscommunications services via Global System for Mobile Communications (GSM) protocol, and is also configured to receive communicationscommunications services via Session Initiation Protocol (SIP) over IEEE 802.1 Ix. However, the mobile station 10 might instead be

configured to receive communicationscommxinications services using via Code Division Multiple Access (CDMA) protocol and Bluetooth. The mobile station 10 might be configured for communication using protocols other than GSM ₅ CDMA, IEEE 802. Hx, and Bluetooth. Further, although in the examples described herein the mobile station 10 is configured for communication with only two incompatible communications networks, the mobile station 10 may be configured for direct communication with more than two incompatible communications networks. Further, as will be discussed below with reference to Figs. 7 to 9, the mobile station may be configured for direct communication with only one of the communications networks.

[0022] The mobile station 10 is uniquely identified in the communicationscommunications system 100 by an ϊMEI (International Mobile Equipment Identity), The mobile station 10 includes a SmartCard, commonly referred to as a SlM (Subscriber Identity Module), upon which is stored an IMSI (International Mobile Subscriber Identity). The IMSI acts as an identifier which the communications system 100 uses to identify the subscriber that is assigned to the mobile station 10.

[0023] The communications system 100 comprises a plurality of communications networks, and a multi-access subscription server 400 coupled to the communications networks. The Communications networks may be compatible or incompatible with each other. For instance, the communications system 100 might comprise a circuit-switched network, and a packet'Switched network that is coupled to the circuit-switched network. In the example embodiment of Fig. 1, the communications system 100 comprises a GSM network 200, and also comprises a pre-IMS (Internet Protocol Multimedia Subsystem) SIP (Session Initiation Protocol ) network 300 (hereinafter "SIP network"). However, instead of a GSM network, the communications system 100 might instead comprise a CDMA network. The communications system 100 might comprise a GSM network and a CDMA network. Other combinations of communications networks are encompassed by the communications system 100. Further, although in the examples described herein the communications system 100 includes only two incompatible communications networks,

the communications system 100 might include more than two incompatible communications networks.

[0024] As mentioned, in the embodiment of Fig. I ₃ the circuit-switched network 200 is implemented as a GSM-based wireless cellular network. It should be understood that the GSM network 200 is not limited to supporting conventional GSM telephony services, but may also support GSM overlayed services, such as GPRS (General Packet Radio Services). However, for convenience, the teπn "GSM network" is intended herein to encompass all network services based on GSM,

[0025] The GSM network 200 comprises a plurality of base station subsystems (BSS) 204, and a plurality of network subsystems 206. Although the GSM network 200 is shown comprising a single BSS 204, and a single network subsystem 206, typically the GSM networks 200 comprises several BSSs 204 and.network subsystems 206.

[0026] Each BSS 204 is deployed in a respective geographical region, and communicates with the mobile stations 10 that are located in their respective geographical region over a wireless link. Each BSS 204 comprises one or more base station transceivers 210, and a base station controller 212. Each base station transceiver 210 includes one or more radio transceiveis that establish the wireless link between the mobile stations 10 and the base station subsystem 204. The base station controller 212 controls the base station transceivers 210, and manages the wireless link between the mobile stations 10 and the base station subsystem 204.

[0027] The network subsystems 206 are in communication with one or more of the BSSs 204, and are also in communication with a fixed telephony network 50, such as PSTN (Public Switched Telephone Network) via a GMSC (Gateway Mobile Services Switching Centre) 216. The GMSC 216 acts as an interface or switching node between the communications system 100 and the fixed telephony network 50, and receives incoming voice and data communications (either from the fixed network 50, the GSM network 200, or the SIP network 300) that are intended for the subscriber that is assigned

to the mobile station 10. The GMSC 216 is in communication with the multi-access subscription server 400, and is configured to route these incoming communications to the appropriate destination. As will be explained, the multi-access subscription server 400 is configured to determine the appropriate destination for terminating incoming communications, based on a set of communications network preferences that are associated with the subscriber.

[0028] Each network subsystem 206 comprises a MSC (Mobile Services Switching Centre) 218, and a VLR (Visitor Location Register) 220. Each MSC 218 communicates with the associated VLR 220 and the multi-access subscription server 400 via Mobile Application Part (MAP) over SS7 (Signaling System Number 7) protocol. Each MSC 218 is in communication with the base station controllers 212 of the associated BSSs 204, and acts as an interface or switching node between the network subsystem 206 and the GMSC 216.

[0029] As will be explained, the MSC 218, in cooperation with the VLR 220 and the multi-access subscription server 400, provides the functionality required to provide communications services for the mobile station 10, such as registration, authentication, location updating, and call routing. Although the MSC 218 and the VLR 220 are shown as separate functional entities, typically the MSC 218 and the VLR 220 of each network subsystem 206 are implemented together as a single networked computer, so that the geographical region controlled by the MSC 218 corresponds to the geographical region controlled by the VLR 220.

[0030] Each VLR 220 contains administrative information required to provide subscribed services for each mobile station 10 located within the geographical region controlled by the VLR 220, Typically, the VLR 220 maintains the IMSI, a TMSI (Temporary Mobile Subscriber Identity), a MSISDN (Mobile Subscriber Integrated Service Digital Network) directory number, and a MSRN (Mobile Station Roaming Number) for each mobile station 10 within the controlled geographical region. The TMSI is a temporary identifier that is local to the servicing MSCWLR and used by the

MSC/VLR 218, 220 to temporarily identify the mobile station 10. The MSISDN is a phone number that is associated with the subscriber who is assigned to the mobile station 10, Each subscriber's MSISDN is a unique number on the GSM network 200. The MSRN is a temporary directory number that the GMSC 216 uses to formatan incoming call for the serving MSC 218.

[0031] In the embodiment of Fig. 1, the packet-switched network 300 comprises a SIP network that implements Session Initiation Protocol for communication with the mobile station 10. The SIP network 300 comprises a plurality of end points 304, and a core network 306, Although the SIP network 300 is shown comprising a single end point 304, typically the SIP network 300 comprises several end points 304.

[0032] The end point 304 may comprise a wireless base station 308, and a local base station controller 310 coupled to the wireless base station 308. Optionally, the end point 304 also includes a fixed Plain Old Telephone System (POTS) handset 20, and the local base station controller 310 includes an interface for interfacing with the POTS handset 20.

[0033] The base station 308 includes a radio transceiver, the coverage area of which defines a local area cell. The base station 308 may communicate with local wireless communications devices, such as the mobile station 10, over the local area cell via a EEEE 802.1 Ix. However, the base station 308 may implement short-range wireless communications protocols other than IEEE 802.1 Ix. The base station 308 is connected to the local base station controller 310 via a wired or optical link.

[0034] The local base station controller 310 comprises a computer server, and acts as a physical connection between the mobile station 10 (or fixed handset 20) and the core network 306. The local base station controller 310 interfaces with the core network 306 via a wired or optical link, and facilitates communication between the mobile station 10 (and fixed handset 20) and the core network 306.

[0035] The core network 306 is implemented as an IP-based network, and comprises a Softswitch 314 and a proxy server 312. The Softswitch 314 is coupled to the fixed telephone network 50, the GMSC 216 and the proxy server 312, and acts as an gateway between the fixed telephone network 50, the GSM network 200 and the SIP network 300.

[0036] The proxy server 312 is implemented as a networked computer server that is interfaced with the multi-access subscription server 400, the local base station controller 310, and the Softswitch 314. The proxy server 312 typically comprises a noπ- volatile memory, a main memory, and a central processing unit in communication with the nonvolatile memory and the main memory. The non-volatile memory carries computer processing instructions for the proxy server 312 which, when loaded into the main memory and executed by the central processing unit, define a SIP-Proxy 316 and a SIP- Registrar 318.

[0037] The SIP-Proxy 316 receives incoming voice or data communications from the Softswitch 314 mat are intended for the subscriber that is assigned to the mobile station 10 atϊd/or the fixed handset 20. The SIP-Proxy 316 is configured to route these incoming communications to the appropriate destination, using routing information provided by the multi-access subscription server 400. As mentioned, the multi-access subscription server 400 determines the appropriate destination for terminating incoming communications, based on a set of communications network preferences that axe associated with the subscriber.

[0038] The SIP-Registrar 318 receives registration messages from the mobile station 10 via the core network 306, and is configured to maintain on the proxy server 312 a location lookup table that associates for each mobile station 10 a Uniform Resource Identifier (SEP:URI or Tel:URI) that identifies the mobile station 10 on the SIP Network 300. Each Tel.'URI is a unique phone number on the SIP Network 300. The SIP- Registrar 318 can also be configured to notify the multi-access subscription server 400 upon receipt of request from a mobile station 10 for registration on the SIP Network 300.

[0039] The multi-access subscription server 400 is implemented as a networked computer server that communicates with the network subsystem 206 and the GMSC 216 via MAP over SS7 protocol. The multi-access subscription server 400 also comrounicates with the proxy server 312 via SIP over IP. The multi-access subscription server 400 typically comprises a non-volatile memory, a main memory, and a central processing unit in communication with the non-volatile memory and the main memory. The non-volatile memory carries computer processing instructions for the multi-access subscription server 400 which, when loaded into the main memory and executed by the central processing unit, define a network manager 402. The non-volatile memory also comprises a subscriber profile database 404 which the network manager 402 uses to manage the communications services that are provided to mobile stations 10 that are registered with the GSM network 200 and the SIP Network 300. Although, in this embodiment, the network manager 402 is implemented in computer software, the network manager 402 may instead be implemented in electronics hardware.

[0040] The subscriber profile database 404 includes subscriber data for the subscriber of each mobile station 10 that is registered with the GSM network 200. The GSM subscriber data includes each subscriber's IMSI and MSISDN, and the MSC/VLR 218, 220 that is currently servicing each mobile station 10. The GSM subscriber data also includes each subscriber's secret encryption key for the GSM network 200, and subscription information that identifies the communications services to which each subscriber is entitled to receive from the GSM network 200.

[0041] The subscriber profile database 404 also includes subscriber data for the subscriber of each mobile station 10 that is registered with the SIP network 300, The SIP subscriber data includes each subscriber's Address of Record (AOR), and the PSTN directory number and the TeIrURI (or SIP:URI) of each subscriber's mobile station 10 and the TelrURl (or SIP:URI) of each subscriber's mobile station 10. The SIP subscriber data also includes each subscriber's secret encryption key for the SIP network 300, and subscription information that identifies the communications services to which each subscriber is entitled to receive from the SIP network 300-

[0042] A subscriber may subscribe to services on the GSM network 200 and on the SIP network 300. The SIP subscriber data and the GSM subscriber data for such subscriber are linked via the subscriber's subscription information.

[0043] The network manager 402 comprises a service request processor 406, and a network selector 408. The service request processor 406 is interfaced to the MSC/VLR 218, 220 of the GSM network 200 and to the SIP-Registrar 318 of the SIP network 300. For each subscriber of the GSM network 200 and the SIP network 300, the service request processor 406 maintains, in the subscriber profile, communications network preferences for each of the communications networks 200, 300. The content and purpose of the communications network preferences will be described below.

[0044] The service request processor' ¹ 406 is configured to process communication service requests that are initiated from the mobile station 10 when the subscriber of the mobile station 10 seeks to receive communications services from the communications networks 200, 300. For instance, when the mobile station 10 issues an IMSI attach or Location Update command to the GSM network 200, the service request processor 406 updates the subscriber profile of the subscriber that is associated with the mobile station 10 to identify the current location (e.g. servicing MSC/VLR 218, 220) of the mobile station 10 on the GSM network 200. Similarly, when the mobile station 10 issues a SIP Register command (specifying the SIP:URI or Tel:URI assigned to the mobile station 10) to the SIP network 300, the service request processor 406 updates the subscriber profile of the subscriber that is associated with the mobile station 10 to indicate that the mobile station 10 having the specified SIPrURI (or TehURI) has registered on the SIP Network 300.

[0045] The network selector 408 is interfaced to the GMSC 216 of the GSM network 200 and to the SIP Proxy 318 of the SIP network 300. Upon receipt of an incoming communication (at the GMSC 216 or the SIP Proxy 318) intended for one of the subscribers registered with the GSM network 200 and/or the SIP Network 300, the

network selector 408 selects between the GSM network 200 and the SIP Network 300 for the provision of communications services to the subscriber.

[0046] As discussed, the service request processor 406 maintains in the subscriber profile database 404 for each subscriber a subscriber profile that defines communications network preferences for each of the communications networks 200, 300. The network selector 408 is interfaced to the subscriber profile database 404, and is configured to cause the GMSC 216 or the SIP-Proxy 318 to route the incoming communication to the subscriber, via the GSM network 200 or the SIP Network 300, based on the intended subscriber's communications network preferences.

[0047] The communications network preferences specify the manner in which an incoming call is terminated for the subscriber. The communications network preferences may specify a primary communications network (e.g. the GSM network 200), and a secondary communications network (e.g. the SIP Network 300), and may require the network selector 408 to select between the primary and the secondary communications networks depending upon the current time of day, and/or day of week, and/or the availability of the mobile station 10 over each communications network, The communications network preferences may also comprise a list of known (registered or predefined) locations at which the subscriber has mobile stations 10, and specify criteria for selecting between these locations. For example, the communications network preferences may specify a secondary communications device (such as the fixed handset 20) on the secondary communications network if the mobile station 10 is not reachable via the specified communications network. Other communications network preferences that are suitable for routing an incoming communication to a subscriber are intended to be encompassed by this disclosure.

[0048] Although, in the embodiment of Fig. 1, the SIP-Registrar 318 is provided on the proxy server 312, the SIP-Registrar 318 may be implemented on the multi-access subscription server 400 instead. In this variation (not shown), the SIP-Registrar 318

maintains the location lookup table on the multi-access subscription server 400, rather than on the proxy scrvei 312,

[0049] The operation of the communications system 100 will now be described with reference to Figs. 2 to 6.

USER REGISTRATION

[0050] Fig. 2a depicts the message traffic over the communications system 100 when the mobile station 10 registers with the GSM network 200. At step S200, the mobile station 10 implicitly registers to receive communications services from the GSM network 200 by issuing a Location Update Request message to the GSM network 200. Alternately, if the mobile station 10 is configured to receive data services over the GSM network 200, the mobile station 10 might register to receive data services by issuing a GPRS Attach message to the GSM network 200.

[0051] The Location Update Request (or GPRS Attach) message, which includes the TMSI (or P-TMSI (Packet-TMSI) in the case of a GPRS Attach message) that was assigned to the mobile station 10, is received by one of the BSSs 204, and is forwarded to the serving MSC/VLR 218, 220. At step S204, the serving MSC/VLR 21S ₃ 220 issues a MAP Update Location message to the service request processor 406, which message includes the IMSI of the mobile station 10.

[0052] If the subscriber data is maintained on the multi-access subscription server 400, the service request processor 406 updates the subscriber profile in the subscriber profile database 404 to associate the subscriber's IMSI and MSISDN with the address of the serving MSC/VLR 218, 220. If the subscriber data is maintained on the proxy server 312, the service request processor 406 may proxy a SlP Register message to the proxy server 312, to thereby update the subscriber profile. An embodiment in which the subscriber data is maintained by proxy will be discussed below, with reference to Figs. 7 to 9.

[0053] At step S206, the service request processor 406 responds to the serving MSC/VLR 218, 220 with a MAP Insert Subscriber Data (ISD) message that includes the subscriber's IMSI and MSISDN. The serving MSC/VLR 218, 220 maintains a local copy of the IMSI - MSISDN pair, and then responds to the service request processor 1406 with an ISD acknowledgement message, at step S208. The service request processor 406 responds to the serviing MSC/VLR 218, 220 with an Update Location (or GPRS Attach) acknowledgement message, at step $210, and then issues a MM / Location Update (or GPRS Attach) acknowledgement to the mobile station 10', at step S212.

[0054] Fig. 2b depicts the message traffic over the communications system 100 when the mobile station 10 registers with the SlP Network 300. At step S214, the mobile station 10 of the SIP end point 304 implicitly registers to receive communications services from the SIP Network 300 by issuing a SIP Register message to the SIP Network 300. The SIP Register message, which includes the SIP:URI (or Tel:URI) of the subscriber's mobile station 10, is received by the SIP-Registrar 318, together with the SIP address of the end point 304. As mentioned, the SIP-Registrar 318 may be provided on the proxy server 312 or on the multi-access subscription server 400.

[0055] At step S216, the SIP-Registrar 318 notifies the network manager 402 that it has received a registration request from a mobile station 10, and includes the SIP:URI (or Tel:URI) of the mobile station 10.

[0056] If the subscriber that is associated with the SIP:URI (or TeIrURI) is entitled to receive communications services from the SIP network 300, the service request processor 406 updates the subscriber profile in the subscriber profile database 404 to indicate that the subscriber has registered with the SIP network 300- The service request processor 406 then responds to the SIP-Registrar 318 with an acknowledgment message, at step S218. The SIP-Registrar 318 then updates the location lookup table with an entry that includes the Tel:URI of the mobile station 10 and the SIP address of the end point 304 that is servicing the mobile station 10, and then responds to the SIP end point 304 with an acknowledgment message, at step S220.

[00S7] Since the wireless coverage area of the GSM network 200 is usually larger than that of the SIP network 300, a mobile station 10 might move into range of the GSM network 200 before moving into range of the SB? network 300. Therefore, in the example of Fig. 2, the mobile station 10 registers with the GSM network 200 before registering with the SIP network 300. However, a mobile station 10 might be in range of the SIP network 300 before moving into range of the GSM network 200. Therefore, the mobile station 10 might register with the SP network 300 before registering with the GSM network 200.

GMSC TERMINATING CALL OVER GSM NETWORK

[0058] Fig. 3 depicts the message traffic over the communications system 100 when the communications system 100 receives a terminating call at the GMSC 216 intended for the subscriber that is associated with the mobile station 10. hi this example, it is assumed that the communications network preferences of the subscriber require the call to be routed to the mobile station via (he GSM network 200.

[0059] Following the example of Fig. 2, the mobile station 10 has registered with both the GSM network 200 and the SIP network 300. As will be explained however, simultaneous registration with both networks is not a requirement of the communications system 100.

[0060] Initially, the GMSC 216 receives an ISUP IAM message from the fixed network 50. Then, at step S300, the GMSC 216 queries the network manager 402 with a MAP Send Routing Information (SRI) message, which includes the MSISDN that is associated with the intended subscriber. Using the received MSISDN, the network selector 408 queries the subscriber profile database 404 for the subscriber profile that is associated with the intended subscriber.

[0061] As mentioned, the subscriber profile includes subscription information that identifies the communications services to which the subscriber is entitled to receive, and

the subscriber's communications network preferences for each of the communications networks 20O ₃ 300. Therefore, the network selector 408 selects one of the communications networks 200, 300 for terminating the call, based on the communications services that the subscriber is entitled to receive and the subscriber's network preferences.

[0062] Since, in this example, the network preferences indicate that the call should be routed to the mobile station 10 via the GSM network 200, at step S302 the network selector 408 issues a MAP / PRN (Provide Roaming Number) message to the serving MSC/VLR 218, 220, which message includes the IMS! of the mobile station 10. The MSCAHLR 218, 220 associates a temporary MSRN with the received IMSI, and maintains a copy of the IMSI - TMSI - MSRN association. At step S304, the serving MSCATLR 218, 220 responds to the network selector 408 with a MAP / PRN Result message, which message includes the MSRN.

[0063] At step S306, the network selector 408 responds to the GMSC 216 by issuing a SRI Result message to the GMSC 116, which message includes the MSRN. At step S308, the GMSC 216 issues an ISUP Initial Address message to the MSC/VLR 218, 220, which message includes the received MSRN. From the MSRN ₅ the MSCA ⁷ LR 218, 220 determines the TMSI that is associated with the MSRN, and then uses the TMSI to page the mobile station 10 (via the BSS 204).

[0064] In this example, the mobile station 10 was registered with, and was in communication range of, both the GSM network 200 and the SIP Network 300 when an incoming call was received at the GMSC 216. Therefore, the network selector 408 selected the communications network (GSM network 200) while the mobile station 10 was in communication range of both the communications networks 200, 300, based on the subscriber's communications network preferences.

[0065] However, the mobile station 10 might have moved out of range of the GSM network 200 after the mobile station 10 issued communication service requests to both of

the communications networks 200, 300. If the mobile station 10 is no longer registered on the GSM network, the subscriber's IMSI in the subscriber profile database 404 won't have an association to a MSC/VLR 218, 220. In this situation, at step $302 the network selector 408 might provide alternate routing information (for example to the mobile station 10 or the fixed handset 20 via the SIP network 300), depending upon the subscriber's communications network preferences.

GMSC TERMINATING CALL OVER SIP NETWORK

[0066] Fig. 4 depicts the message traffic over the communications system 100 when the communications system 100 receives a terminating call at the GMSC 216 intended for the subscriber that is associated with the mobile station 10. In this example, it is assumed that the communications network preferences of the subscriber require the call to be routed to the mobile station via the SEP network 300.

[0067] At step S400, the GMSC 216 queries the network manager 402 with a MAP Send Routing Information (SRI) message, which includes the MSISDN that is associated with the intended subscriber. Using the received MSISDN, the network selector 408 queries the subscriber profile database 404 for the subscriber profile that is associated with the intended subscriber.

[0068] The network selector 408 selects one of the communications networks 200, 300 for terminating the call, based on the communications services that the subscriber is entitled to receive and the subscriber's network preferences. Since, in this example, the network preferences indicate that the call should be routed to the subscriber via the SIP network 300, at step S402 the network selector 408 responds to the GMSC 216 by issuing a SRI Result message to the GMSC 116, which message includes the PSTN directory number specified by the network preferences. The directory number included in the SRI Result message may be associated with the mobile station 10 or the fixed handset 20, as determined by the network preferences.

[0069] At step S404, the GMSC 216 issues a ISUP IAM message to the Softswitch 314, which message includes the received directory number. At step S406, the Softswitch 314 issues a SP Invite message over the SIP Network 300, which message includes the directory number received from the GMSC 216. From the directory number, the SIP- Proxy 316 queries the location lookup table for the SIP address of the end point 304 having the specified directory number. The SIP-Proxy 316 forwards the SIP Invite message to the specified end point 304, at step S408.

[0070] The mobile station 10 (or fixed handset 20) of the SIP end point 304 answers the call by responding to the SIP-Proxy 316 with an acknowledgement message, at step S412, that includes the IP address of the mobile station (or fixed handset 20). The SIP- Proxy 316 forwards the acknowledgement message to the Softswitch 314, at step S4I4, whereupon the Softswitch 314 communicates directly with the mobile station 10 (or fixed handset 20) using the EP address specified in the acknowledgement message.

[0071] In this example, the mobile station 10 was registered with, and was in communication range of, both the GSM network 200 and the SlP Network 300 when an incoming call was received at the GMSC 216. Therefore, the network selector 408 selected the communications network (SEP network 300) while the mobile station 10 was in communication range of both the communications networks 200, 300, based on the subscriber's communications network preferences.

[0072] However, the mobile station 10 might have moved out of range of the SIP network 300 after the mobile station 10 issued communication service requests to both of the communications networks 200, 300. If the Softswitch 314 determines that the mobile station 10 is not reachable on the SIP network 300, the Softswitch 314 might prompt the network selector 408 to provide alternate routing information (for example to the fixed handsel 20 via the SIP network 300, or to the mobile station 10 via the GSM network 200), depending upon the subscriber's communications network preferences.

SOFTSWITCH TERMINATING CALL OVER SIP NETWORK

[0073] Fig. 5 depicts the message traffic over the communications system 100 when the communications system 100 receives a terminating call at the Softswitch 314 intended for the subscriber that is associated with the mobile station 10. In this example, it is assumed that the communications network preferences of the subscriber require the call to be routed to the mobile station via the SIP network 300.

[0074] At step S500, the Softswitch 314 issues a SIP Invite message over the SIP Network 300, which message includes the SIP:URI (or Tel:URI) that is associated with the intended subscriber. The SIP-Proxy 316 forwards the SIP Invite message to the network manager 402, at step S502. Using the received SIP:URI (or TehURI), the network selector 408 queries the subscriber profile database 404 for the subscriber profile that is associated with the intended subscriber.

[0075] The network selector 408 selects one of the communications networks 200, 300 for terminating the call, based on the communications services that the subscriber is entitled to receive and the subscriber's network preferences. Since, in this example, the network preferences indicate that the call should be routed to the subscriber via the SIP network 300, at step S504 the network selector 408 responds to the SIP-Proxy 316 with a redirect message (e.g. SIP 302 Moved Temporarily) message that includes the SIPiURI (or Tel:URI) of the end point 304 associated with the subscriber. The SIPrURI (Tel:URI) may be associated with the mobile station 10 or the fixed handset 20, as determined by the network preferences.

[0076] The SIP-Proxy 316 then queries the location lookup table for the SIP address of the end point 304 that is currently servicing the mobile station 10 (or the fixed handset 20) having the specified SIP:URI (Tel:URI). The SIP-Proxy 316 forwards the SIP Invite message to the specified end point 304, at step S506, together with the SEP:URI (TeIiURl).

[0077] At step S510, the mobile station 10 (or fixed handset 20) of the SIP end point 304 answers the call by responding to the SIP-Proxy 316 with an acknowledgement

message that includes the IP address of the mobile station (or fixed handset 20). The SIP-Proxy 316 forwards the acknowledgement message to the Softswitch 314, at step S512, whereupon the Softswitch 314 communicates directly with the mobile station 10 (or fixed handset 20) using the IP address specified in the acknowledgement message.

[0078] In this example, the mobile station 10 was registered with, and was in communication range of, both the GSM network 200 and the SIP Network 300 when an incoming call was received at the GMSC 216. However, the mobile station 10 might have moved out of range of the SIP network 300 after the mobile station 10 issued communication service requests to both of the communications networks 200, 300. If the Softswitch 314 determines that the mobile station 10 is not reachable on the SIP network 300, the SIP Softswitch 314 might prompt the network selector 408 to provide alternate routing information (for example to the fixed handset 20 via the SIP network 300, or to the mobile station 10 via the GSM network 200), depending upon the subscriber's communications network preferences.

SOFTSWITCH TERMINATING CALL OVER GSM NETWORK [0079] Fig. 6 depicts the message traffic over the communications system 100 when the communications system 100 receives a terminating call at the Softswitch 314 intended for the subscriber that is associated with the mobile station 10. In this example, it is assumed that the communications network preferences of the subscriber require the call to be routed to the mobile station via the GSM network 200.

[0080] At step S600, the Softswitch 314 issues a SIP Invite message over the SIP Network 300, which message includes the SIP:URJ (or TehURI) that is associated with the intended subscriber. The SIP-Proxy 316 forwards the SIP Invite Message to the network manager 402, at step S602, which message includes the SIP:URI. Using the received SIP:URI (or TehURI), the network selector 408 queries the subscriber profile database 404 for the subscriber profile that is associated with the intended subscriber.

[0081] The network selector 408 selects one of the communications networks 200, 300 for terminating the call, based on the cσrnmunications services that the subscriber is entitled to receive and the subscriber's network preferences. Since, in this example, the network preferences indicate that the call should be routed to the subscriber via the GSM network 200, at step S604 the network selector 408 issues a MAP / PKN (Provide Roaming Number) message to the MSC/VLR 218, 220, which message includes the IMSI of the mobile station 10. The MSC/VLR 218, 220 associates a temporary MSRN with the received IMSI, and maintains a copy of the IMSI - TMSI - MSRN association. At step S606, the MSC/VLR 218, 220 responds to the network selector 408 with a MAP / PRN Result message, which message includes the MSRN.

[0082] The network selector 408 responds to the SIP-Proxy 316, at step S608, with a redirect message that includes the MSRN of the mobile station 10. The redirect message may be a 302 Moved Temporarily message, or a 300 Moved Temporarily Multiple Choices. The latter message is advantageous since it allows the network selector 408 to facilitate multiple and sequential ringing. The SIP-Proxy 316 forwards the redirect message to the Softswitch 314, at step S610. Upon receipt of the redirect message, the Softswitch 314 routes the call to the serving MSC/VLR 218, 220, at step S612, with an ISUP IAM message that includes the MSRN provided by the network selector 408.

[0083] From the MSRN, the MSC/VLR 218, 220 determines the TMSI that is associated with the MSRN, and then issues a RR / Paging message (via the BSS 204), at step S616, which message includes the TMSI. The mobile station 10 that was assigned the matching TMSI answers the call.

[0084] In this example, the mobile station 10 was registered with, and was in communication range of, both the GSM network 200 and the SIP Network 300 when an incoming call was received at the GMSC 216. However, the mobile station 10 might have moved out of range of the GSM network 200 after the mobile station 10 issued communication service requests to both of the communications networks 200, 300. If the mobile station 10 is no longer registered on the GSM network, the subscriber's IMSI in

the subscriber profile database 404 won't have an association to a MSCA ⁷ LR 218, 220. In this situation, at step S608 the network selector 408 might provide alternate routing information (for example to the mobile station 10 or the fixed handset 20 via the SIP network 300), depending upon the subscriber's Communications network preferences.

COMMUNICATIONS SYSTEM 1100

[0085] Fig. 7 depicts a mobile station 10' in communication with a communications system 1100. The mobile station 10' is substantially the same as the mobile station 10, but comprises a single-mode wireless communications device. The communications system 1100 is similar to the communications system 100, but allows the single-mode mobile stations 10' to receive communications services from a plurality of wireless communications networks. As in the embodiment of Fig. 1, the communications networks may be compatible or "incompatible" with each other.

[0086] As shown, the communications system 1100 comprises a plurality of communications networks, and a multi-access subscription server (MSS) 1400 coupled to the communications networks. In the embodiment of Fig. 7, one of the networks comprises the aforementioned GSM network 200, and another one of the networks comprises an IMS-compliant SIP network 1300 (hereinafter "IMS network"). Again, other technologies and combinations of communications networks are encompassed by the communications system 1100.

[0087] The IMS network 1300 is substantially identical to the SIP network 300, and comprises a plurality of the end points 304, and a core network 1306. The core network 1306 is implemented as an IP-based network, and comprises a proxy server 1312, a Home Subscriber Server (HSS) 1320, and the Softswitch 314. The proxy server 1312 comprises a networked computer server that comprises a non-volatile memory, a main memory, and a central processing unit in communication with the non-volatile memory and the main memory.

[0088] The non-volatile memoiy carries computer processing instructions for the proxy server 1312 which, when loaded into the main memory and executed by the central processing unit, define an IMS Proxy-Call Session Control Function (P-CSCF) procedure that implements P-CSCF functionality, an IMS Interrogating-CSCF (I-CSCF) procedure that implements I-CSCF functionality, and an IMS Serving-CSCF (S-CSCF) procedure that implements S-CSCF functionality. The S-CSCF procedure maintains on the proxy server 1312 a location lookup table that associates for each mobile station 10' a Uniform Resource Identifier (SIP:URI or Tel:URI) that identifies the mobile station 10 on the IMS Network 300, and the P-CSCF that is currently servicing the mobile station 10'. Although, in the embodiment of Fig. 7, the IMS network 1300 only comprises a single proxy server 1312 (having a single P-CSCF procedure, a single I-CSCF procedure, and a single S-CSCF procedure), typically the IMS network 1300 will have a plurality of proxy servers and CSCF procedures.

[0089] The HSS 1320 comprises a networked computer server that is configured to select one of the S-CSCF procedures for the processing of communications with the mobile station 10'. The HSS 1320 also maintains an IMS subscriber profile database that includes IMS subscriber data for the subscriber of each mobile station 10' that is registered with the IMS network 1300. Each subscriber's IMS subscriber data includes one or more IP Media Public Identities (IMPU), an IP Media Private Identity (IMPI), the address of the S-CSCF that is assigned to the subscriber's mobile station 10', and subscription information that identifies the communications services to which the subscriber is entitled to receive from the IMS network 1300. The IMPU and/or the IMPI may comprise the SIPrURI or the TehURI of the subscriber's mobile station 10'.

[0090] The multi-access subscription server (MSS) 1400 is implemented as a networked computer server that communicates with the network subsystem 206 and the GMSC 216 of the GSM network 200, and the proxy server 1312 of the IMS network 1300. The muJti-access subscription server 1400 typically comprises a non-volatile memory, a main memory, and a central processing unit in communication with the nonvolatile memory and the main memory. The non-volatile memory carries computer

processing instructions for the multi-access subscription server 1400 which, when loaded into the main memory and executed by the central processing unit, define a network manager 1402. The non-volatile memory also comprises a GSM subscriber profile database 1404 which the network manager 1402 uses to manage the communications services that are provided to the mobile stations 10'. Again, although in this example, the network manager 1402 is implemented in computer software, the network manager 1402 may instead be implemented in electronics hardware.

[0091] The GSM subscriber profile database 1404 includes subscriber data for the subscriber of each mobile station 10' that is registered with the GSM network 200. The GSM subscriber data includes each subscriber's IMSI ₅ MSISDN, SIP:URI or TehURI, the PSTN directory number of the subscriber's mobile station 10', and the MSC/VLR 218, 220 that is currently servicing each mobile station 10', The GSM subscriber data also includes each subscriber's secret encryption key for the GSM network 200, and subscription information that identifies the communications services to which each subscriber is entitled to receive from the GSM network 200.

[0092] The network manager 1402 comprises a service request processor 1406, and a network selector 1408. The service request processor 1406 is interfaced to the MSC/VLR 218, 220 of the GSM network 200 and to the proxy server 1312 of the IMS network 1300. For each subscriber of the GSM network 200 and the IMS network 1300, the service request processor 1406 maintains communications network preferences for the GSM network 200 and the IMS network 1300.

[0093] The service request processor 1406 is also configured to process communication service requests that are initiated from the mobile station 10 ^J when the subscriber of the mobile station 10' seeks to receive communications services from the communications networks 200, 1300. However, in contrast to the embodiment of Fig. 1, the service request processor 1406 acts as a proxy to maintain the IMS subscriber data on the HSS 1320.

[0094] Therefore, when the mobile station 10' issues a Location Update Request (or GPRS Attach) message to the GSM network 200, the service request processor 1406 updates the subscriber profile of the subscriber that is associated with the mobile station 10' to identify the current location of the mobile station 10' on the GSM network 200. However, in contrast to the service request processor 406, the service request processor 1406 also proxies a SIP Register command to the IMS network 1300 requesting that the proxy server 1312 update the IMS subscriber profile of the subscriber that is associated with the mobile station 10' and thereby register the mobile station 10 on the IMS Network 1300.

[0095] Upon receipt of an incoming communication (at the GMSC 216 or the proxy server 1312) intended for one of the subscribers registered with the GSM network 200 and the IMS Network 1300, the network selector 1408 selects between the GSM network 200 and the IMS Network 1300 for the provision of communications services to the subscriber.

[0096] As discussed, the service request processor 1406 maintains for each subscriber a subscriber profile that defines communications network preferences for each of the communications networks 200, 300, The network selector 1408 is configured to cause the GMSC 216 or the proxy server 1312 to route the incoming communication to the subscriber, via the GSM network 200 or the IMS Network 1300, based on the intended subscriber's communications network preferences.

[0097] The operation of the communications system 1100 will now be described with reference to Figs. S and 9.

USER REGISTRATION

[0098] Fig. 8 depicts the message traffic over the communications system 1100 when the mobile station 10' registers with the GSM network 200. In this example, the mohile station 10' is configured to receive communications services directly from the GSM

network 200, but cannot receive communications services directly from the IMS network 1300,

[0099] At step S 1200, the mobile station 10 implicitly registers to receive communications services from the GSM network 200 by issuing Location Update Request (or GPRS Attach) message to the GSM network 200. As above, if the mobile station 10' has not already registered with the GSM network 200, the mobile station 10' may issue an IMSI Attach message to the GSM network 200 instead.

[00100] The IMSI attach message, which includes the TMSI (or P-TMSI in the case of a GPRS Attach message) of the mobile station 10', is received by one of the BSSs 204, and is forwarded to the serving MSC/VLR 218, 220. At step S 1206, the serving MSCATLR 218, 220 issues a MAP Location Update message to the service request processor 1406, which message includes the IMSI of the mobile station 10'.

[00101] The service request processor 1406 updates the GSM subscriber profile in the GSM subscriber profile database 1404 to associate the subscriber's IMSI, MSISDN and SIP=URI (or Tel:URI) with the address of the serving MSC/VLR 218, 220. At step Sl 208, the service request processor 1406 responds to the serving MSC/VLR 218, 220 with a MAP ISD message that includes the subscriber's IMSI and MSISDN. The MSCA ⁷ LR 218, 220 maintains a local copy of the IMSI - MSISDN pair, and then responds to the service request processor 1406 with an ISD acknowledgement message, at step S 1210. The service request processor 1406 then responds to the serviing MSCAT-R 218, 220 with an Update Location acknowledgement message, at step S1212, and then issues a MM / Location Update (or GPRS Attach) acknowledgement to the mobile station 10', at step S 1214.

[00102] Further, after the service request processor 1406 issues the MAP ISD message at step S 1208 (or simulataneously therewith), the service request processor 1406 proxies a SIP Register message to the IMS Network 1300, at step Sl 216. The SIP Register message, which includes the SIP:URI (or TeIrURI) of the mobile station 10', is received

by the P-CSCF procedure on the proxy server 1312. At step S 1218, the P-CSCF procedure forwards the SIP Register message to the I-CSCF procedure. At step S 1220, the I-CSCF procedure queries the HSS 1320 with a User Authorization Request (UAR) message for the S-CSCF that will be assigned to the mobile station 10'. The HSS 1320 responds to the I-CSCF procedure, at step S 1222, with a User Authorization Answer (UAA) message that includes the location of the S-CSCF procedure selected to serve this subscriber.

[00103] At step S1224, the I-CSCF procedure redirects the SIP Register message to the identified S-CSCF procedure. The S-CSCF procedure updates the location lookup table on the proxy server 1312 with an entry that includes the SIPrURI (TeIrURI) of the mobile station 10', and the address of the servicing P-CSCF. The S-CSCF procedure issues a Server Assignment Request (SAR) message to the HSS 1320, at step S 1226, requesting that the HSS 1320 update the IMS subscriber profile with an entry that includes the SIP:URI (TeIrURI) of the mobile station 10' and the address of the S-CSCF procedure that is assigned to the mobile station 10'. After the IMS subscriber profile has been updated, the HSS 1320 responds to the S-CSCF procedure with a Server Assignment Answer (SAA) message, at step S 1228.

[00104] The S-CSCF procedure then responds to the service request processor 1406 with an acknowledgement message, at step S 1230, confirming that the mobile station 10' has registered with the IMS network 1300. However, since the P-CSCF procedure that received the SIP Register message from the multi-access subscription server 1400, the S- CSCF procedure considers the multi-access subscription server 1400 as a SIP client. As will become apparent, this registration method allows the mobile station 10' to receive communications services from the IMS network 1300, even though a result the mobile station 10' is only configured to receive communications services from the GSM network 200.

SOFTSWITCH TERMINATING CALL OVER GSM NETWORK

[00105] Fig. 9 depicts the message traffic over the communications system 1100 when the communications system 1100 receives a terminating call at the Softswitch 314 intended for the subscriber that is associated with the mobile station 10'. In this example, it is assumed that the communications network preferences of the subscriber require the call to be routed to the mobile station via the GSM network 200,

[00106] At step S1300, the Softswitch 314 issues a SIP Invite message over the IMS Network 1300 to the proxy server 1316, which message includes the SIP:URI (or TehURI) that is associated with the mobile station 10' of the intended subscriber, The I- CFCS procedure issues a Location-Info-Request (LIR) message to the HSS 1320, at step S1302. The HSS 1320 responds to the I-CFCS procedure, at step S1304, with a Location-Info-Answer (LIA) message that includes the address of the C-CFCS procedure that is assigned to the mobile station 10' having the specified SIP;URi (TehURT).

[00107] At step S 1306, the I-CFCS procedure forwards the SIP Invite message to the S-CFCS procedure. The S-CFCS procedure queries the location lookup table for the node that is associated with the SIP;URI (Tel:URI). Since the SlPrURI (TehURI) is associated in the location lookup table with the multi-access subscription server (MSS) 1400, the S-CFCS procedure includes the address of the multi-access subscription server 1400 in the SIP Invite message. The S-CFCS procedure then forwards the SIP Invite message to the P-CFCS procedure, at step S1308.

[00108] The P-CFCS procedure forwards the SIP Invite message to the multi-access subscription server 1400, at step S 1310, which message includes the SIP:URI (TeIrURI). Using the received SIPrUKJ (TehURI), the network selector 1408 queries the subscriber profile database 1404 for the subscriber profile that is associated with the intended subscriber.

[00109] Since, in this example, the mobile station 10' is incapable of directly receiving communications services from the IMS network 1300, the network preferences indicate that the call should be routed to the subscriber via the GSM network 200. Therefore, at

step S1312 the network selector 1408 issues a MAP / PRN (Provide Roaming Number) message to the MSC/VLR 218, 220, which message includes the IMSI of the mobile station 10'. The MSC/VLR 218, 220 associates a temporary MSRN with the received IMSI, and maintains a copy of the IMSI - TMSI - MSRN association. At step S1314, the MSC/VLR 218, 220 responds to the network selector 1408 with a MAP / PRN Result message, which message includes the MSRN.

[00110] The network selector 1408 responds to the P-CSCF procedure, at step S1316, with a redirect message that includes the MSRN of the mobile station 10'. At step S1318, the P-CSCF procedure forwards the redirect message to the S-CSCF procedure, which, in turn, will issue a SIP Invite message to the Softswitch 314, at step S 1320. Upon receipt of the SEP Invite message, the Softswitch 314 routes the call to the serving MSC/VLR 218, 220, at step S 1322, with an ISUP IAM message that includes the MSRN provided by the network selector 1408. Call termination continues via the GSM network 200, as described above with reference to Fig. 6.