Abstract: In methods and apparatus for obtaining subscriber data for a mobile terminal roaming in a service area of a visited wireless network, the visited wireless network receives from the roaming mobile terminal a registration request specifying an identifier. If subscriber data corresponding to the identifier cannot be found at an HLR of the visited wireless network or at a VLR associated with the HLR, an Intersystem Roaming (ISR) database is searched for an address corresponding to the identifier. If such an address is found, a subscriber data request is transmitted to the address. If no such address is found, the subscriber data request is broadcast to plural wireless networks connected to the visited wireless network. Subscriber data received in response to the subscriber data request is stored in the VLR, and an address corresponding to the identifier is stored in the ISR.