A method performed by one or more computer systems coupled to a packet-based network to determine the location of a mobile device comprises receiving a set of input signals associated with the mobile device from the packet-based network. The set of input signals include a plurality of location components and context information. The method further comprises determining whether the set of input signals include a pair of latitude/longitude coordinates, and determining whether the pair of latitude/longitude coordinates are valid using a set of criteria. The method further comprises defining at least some of the set of criteria using historical data associated with a plurality of mobile devices communicating with the packet-based network. The method further comprises deriving the location of the mobile device using one or more other location components of the plurality of location components and the context information, in response to the pair of latitude/longitude coordinates being marked as invalid.