The location of a wireless mobile device may be estimated using, at least in part, one or more pre-existing Network Measurement Reports (“NMRs”) which include calibration data for a number of locations within a geographic region. The calibration data for these locations is gathered and analyzed so that particular grid points within the geographic region can be determined and associated with a particular set or sets of calibration data from, for example, one or more NMRs. Regions may be defined as a function of any number of parameters and respective predetermined ranges thereof in the NMRs. An intersection of these defined regions may be determined and the location of a mobile device may be estimated as a function of the intersection.