1. A method comprising: receiving mobile phone operational data indicative of user equipment location, the mobile phone operational data comprising location area update messages and periodic registration messages; and performing travel estimation based on the mobile phone operation data, including performing interpolation on data associated with one or more individuals in a population to estimate intermediate positions of a past trajectory of each of the one or more individuals for a specified time period based on a shortest path mesh sequence estimation algorithm to estimate a complete past trajectory for each of the one or more individuals over a sequence of geographical meshes that partition a geographic area based on the mobile phone operational data.