A method and apparatus for locating position of a GPS device is described. In one example, a method for provisioning a mobile device with a model for determining a position of the mobile device in at least one geographic area is provided. The method includes obtaining an estimate of the position of the mobile device, forming one or more satellite orbit models from the estimate and a wide area model, and sending the at least one satellite orbit model to the mobile device. The wide area model is formed from measurements from a plurality of satellites of a Global Positioning System, and the measurements are obtained by a plurality of reference stations.