TELECOMMUNICATION SYSTEMS AND METHODS

摘要

An AMPS/D-AMPS subscriber wishing to roam into the GSM network is provided with a temporary GSM smartcard bearing a number (IMSI) identifying the subscriber as visiting the primary network (A) but also as being registered with the AMPS/D-AMPS network (D). Via a communications link (62) subscriber data from an HLR (58) in the AMPS/D-AMPS network is extracted and stored in the VLR associated with the appropriate cell in the primary network (A). Calls can then be made to and from the subscriber and are billed to the subscriber by the AMPS/D-AMPS network (D) via the communications link. If the subscriber visits one of the other GSM networks (B or C) each of them will recognise that the subscriber is registered with the primary network (A) and will seek subscriber data from the latter's HLR. The primary network (A) will in turn obtain the subscriber data from the HLR (58) in the AMPS/D-AMPS network and transmit this back to the VLR of the network (B or C) where the subscriber is located. In this way, the primary network (A) always controls calls to or from the visiting subscriber.