1. Method for an automatic identification of urban dense areas from cell phones records, by using computing means that receive as inputs: a geographical region R, a time period Δt for which dense areas in the region R need to be computed, a set of BTSs in the region R, a set of CDRs generated by individuals during said time period Δt using said set of BTSs of the region R, a coverage C and a granularity ε, the method comprising: a) constructing a graph G=(V, E), being V=vertexes and E=edges, using Delaunay triangulation, where each vertex v i of V corresponds to bts, of BTS in the geographical region R i and each edge e i,j of E represents connection between bts i and bts j ; b) eliminating from E all the edges in E with a distance between two connecting BTS larger than ε, so that a desired spatial granularity is ensured; c) associating a weight w i,j to each edge e i,j of E that has not been eliminated, said weight representing the average density of the area covered by bts i and bts j during said time period Δt; d) constructing a data structure L that contains said dense areas using said edges of E; and e) applying a “Maximum Spanning Tree” type algorithm to detect dense areas given by said data structure L.