Patent ID: 7904060
Filing Date: 2011-03-08
Classification: H04W

Abstract:
1. A method of providing a preferred roaming list to a telematics unit associated with a vehicle for specifying preferred alternative carrier for use when a primary wireless carrier is not reachable by the telematics unit, the method comprising: transmitting a request to the telematics unit, wherein the request initiates an information transmission from the telematics unit, the information transmission comprising a geographic location of the unit, an SID of a network that the unit is accessing, a call mode of analog or digital cellular, and a vehicle ignition status of on, wherein the vehicle is drivable, or off, wherein the vehicle is not drivable; receiving the information transmission from the telematics unit; selecting a preferred roaming list for transmission to the telematics unit by determining whether the SID is associated with the primary wireless carrier and if not identifying a region containing the telematics unit, and determining whether the identified region is valid for the primary wireless carrier and if not selecting a full carrier preferred roaming list, and otherwise selecting a partial carrier preferred roaming list; transmitting the selected preferred roaming list to the telematics unit if the selected preferred roaming list is a full preferred roaming list or a partial preferred roaming list; and determining whether the vehicle ignition status is on or off if the SID is associated with the primary wireless carrier, and if the status is on, selecting a partial carrier preferred roaming list, and if the status is off determining whether the call mode is analog or digital, and flagging a current preferred roaming list as out of date if the call mode is digital and otherwise selecting a partial carrier preferred roaming list.