A
system and method for determining the location of a
location tracking device employs a
satellite based location determining infrastructure, such as the GPS
system, and a
wireless data communications network such as a cellular voice and / or data network such as
GSM / GPRS. A
location tracking device which cannot easily obtain valid
ephemeris data, or the like, from the
satellite based location determining infrastructure requests the necessary data from a
data set stored at a tracking device hub or the like, via the
wireless communications network. The tracking device hub determines an estimated position of the
location tracking device and this estimated location is transmitted to the location tracking device, along with the appropriate required valid
ephemeris data, or the like, to allow the location tracking device to determine its location. If the location tracking device is still unable to make a
location determination from the
satellite based location determining infrastructure, then the estimated location can be provided. The
topography of the base stations, which is used to estimate the location of the location tracking device, is self-determined by a process executing in the
system and can include base stations from networks operated by different network operators.