a location engine is disclosed that estimates the location of a wireless terminal using cell id , triangulation , gps , rf pattern - matching , or any combination of them . the location engine is adept at discounting the contribution of apparently reasonable but erroneous data . the location engine receives data that are evidence of the location of a wireless terminal at each of a plurality of different times . the location engine then generates an initial hypothesis for the location of the wireless terminal at each time assuming that all of the data is correct and equally probative . next , the location engine generates one alternative hypothesis for each initial hypothesis and each datum assuming that the datum is erroneous . finally , the location engine generates the estimate for the location of the wireless terminal at each time by determining which combination of initial hypotheses and alternative hypothesis is the most self - consistent .