Intelligent roaming method for enabling a mobile station to select a preferred neutral service provider within a communication system

摘要

An intelligent roaming method enables a mobile station (68) to select a preferred neutral service provider from a plurality of service providers within a communication system. The mobile station (68) identifies (S.4) a current communication system servicing a geographic area where the mobile station (68) is presently located. The mobile station (68) determines that the current communication system identified is not serviced by a home service provider (S.6) or by a preferred service provider (S.12) having a roaming agreement with the home service provider. Upon not finding home or preferred service, the mobile station (68) determines whether or not it is programmed for full service priority (S. 16.2). If the mobile station (68) is programmed for full service priority, then mobile station (68) selects (S.16.8) the current communication system as the preferred neutral service provider (S.16.7) only when a frequency band of the current communication system corresponds to a first frequency band of frequency bands listed in priority order in a system access list (SAL) (S.16.4) stored in the mobile station (68) to permit the mobile station (68) to obtain full service (i.e., make and receive calls per roaming agreement) from the current communication system. Alternatively, the mobile station (68) selects (S.16.6) the current communication system as a foreign service provider (S.16.5) when the frequency band of the current communication system does not correspond to the first frequency band of frequency bands listed in priority order in the SAL to permit the mobile station (68) to obtain emergency service (i.e., only make "911" calls and not receive calls) from the current communication system. If the mobile station (68) is not programmed for full service priority, then mobile station selects (S.16.3) the current communication system as a neutral service provider to permit the mobile station (68) to obtain limited service (i.e., only make credit card calls and not receive calls) from the current communication system.