Patent ID: 7738426

Claim:
A roaming gateway comprising: an interworking processor; at least one signaling stack for communication with a non-packet mobile network; a packet interface for communication with a home packet-based network in which it resides; an emulator in the interworking processor for emulating a non-packet mobile network entity to a foreign non-packet network Home Location Register (HLR); and wherein: the gateway resides in a packet network, the emulator emulates a Mobile Switch Center (MSC) or a Visitor Location Register (VLR) to a roaming device non-packet home network HLR, and manages a Session Initiation Protocol (SIP) subscriber profile and Internet Protocol Multimedia Subsystem (IMS)-type subscriber authentication as if the packet network in which the gateway resides were the home network of said roaming device, in which the gateway in combination with the home network HLR operates as an IMS-standard Home Subscriber Server (HSS), and the gateway: receives SIP register requests from a serving Call Session Control Function (CSCF) element, communicates with a different network for subscriber registration, performs filtering of register requests to determine those it can act upon, and relays the SIP register requests for onward processing, and wherein: the gateway examines a user identity in a SIP REGISTER request, upon roaming of an ANSI-41 subscriber or a Global System for Mobile Telecommunications (GSM) subscriber in the packet network, and if the SIP user identity is recognized as a Mobile Directory Number (MDN) of a provisioned subscriber, the gateway retrieves a Mobile Subscriber Identification Number (MSID) and an Electronic Serial Number (ESN) for the subscriber from a database if known in the database, and if not known in the database the gateway resolves the MSID/ESN pair by sending an Mobile Directory Number (MDN)-based request to the subscriber's HLR, avoiding requirement for pre-provisioning of the MDN, MSID, and ESN for a roaming ANSI-41 subscriber in the packet network; the gateway storing the MDN, MSID, and ESN triplet, if the SIP user identity is recognized as a Mobile Subscriber Integrated Services Digital Network Number (MSISDN) of a provisioned subscriber, the gateway retrieves an International Mobile Subscriber Identity (IMSI) for the subscriber from a database if known in the database, and if not known in the database the gateway resolves the IMSI by sending an MSISDN-based request to the subscriber's HLR, avoiding requirement for pre-provisioning of the MSISDN and IMSI for a roaming GSM subscriber in the packet network; the gateway storing the MSISDN/IMSI pair, the gateway stores said subscriber identity information for a subsequent location registration.