A system and method for generating a calibration database in a communications network. A grid of geographic locations may be generated to cover a region in a communications network having a plurality of cellular sites. A set of network measurement reports (NMRs) is generated for the region, the NMR being a collection of measurement parameters observed at selected geographic locations in the grid. A label may then be generated representing a first measurement parameter observed from ones of the plural cellular sites at one of the selected geographic locations, the label including a relative ranking by cellular site of the first measurement parameter. Using this generated label, a calibration database for the communications network may be populated and locations of mobile devices determined therefrom.