Importance

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Abstract

A mobile telephone (UT 1) is configured for dual mode operation, so as to communicate either via an earth-orbiting satellite 3a with a satellite network (SAN 1) or through a conventional land-based cellular network (PLMN 9). In order to provide interworking between the satellite network and the land, cellular network 9, an interworking function (IWF 31) provides data to the cellular network 9 concerning the location of the user terminal (UT 1) in relation to the satellite network. The data is transmitted from the satellite visitor location register (VLR.sub.SAT 1) to the home location register (HLR) of the cellular network 9. The IWF maintains a list of roaming subscribers provisioned with services which are specific to the visited network and not available in the home network. The (IWF 31) is configured to operate with local GSM, DAMPS, PHS or other local land-based networks, depending on the geographic location of the SAN.

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First Claim