A computer implemented method for planning an access network and a transport network of a first mobile telecommunications network to cover a given area, the method comprising: a) determining sites to locate base stations of the first mobile telecommunications network based at least on information obtained from a first database of location and population of all the settlements to be covered by the first mobile telecommunications network; b) obtaining from a second database geographic information about roads in the given area, dividing each road in the given area in a set of road points and associating each site determined in step a) to the nearest road point; c) creating a first graph, called fiber graph, where the fiber graph nodes are the road points, the fiber graph edges are unions between the road points, the fiber graph node weights correspond to the sum of the population covered by the base stations whose sites are associated to each road point, and the edge weights are the road distance between two consecutive nodes; d) determining fiber deployments to connect sites determined in step a) based at least on calculating optimal paths in the fiber graph, where this step comprises: determining the optimal standalone fiber path in the fiber graph for the fiber graph node associated to each site using a first graph solving algorithm; where the method is characterized by: the sites to locate the base stations are determined based also on the location of already existing base stations of a second mobile telecommunications network already deployed in the given area and step a) comprises: a1) selecting as sites to locate base stations, the locations of already existing base stations of the second mobile telecommunications network, and subtracting settlements covered by base stations in said selected sites from the settlements to be covered; a2) selecting a site in the given area that covers the highest population in the settlements to be still covered assuming that a base station located in each site is a tower of a certain height, using a propagation model to estimate the coverage radius; a3) determining the settlements covered by the base station located in said selected site and removing said settlements from the settlements to be covered; a4) repeating steps a2 and a3) until there are no more settlements to covered in the given area. a) determining sites to locate base stations of the first mobile telecommunications network based at least on information obtained from a first database of location and population of all the settlements to be covered by the first mobile telecommunications network; b) obtaining from a second database geographic information about roads in the given area, dividing each road in the given area in a set of road points and associating each site determined in step a) to the nearest road point; c) creating a first graph, called fiber graph, where the fiber graph nodes are the road points, the fiber graph edges are unions between the road points, the fiber graph node weights correspond to the sum of the population covered by the base stations whose sites are associated to each road point, and the edge weights are the road distance between two consecutive nodes; d) determining fiber deployments to connect sites determined in step a) based at least on calculating optimal paths in the fiber graph, where this step comprises: determining the optimal standalone fiber path in the fiber graph for the fiber graph node associated to each site using a first graph solving algorithm; a1) selecting as sites to locate base stations, the locations of already existing base stations of the second mobile telecommunications network, and subtracting settlements covered by base stations in said selected sites from the settlements to be covered; a2) selecting a site in the given area that covers the highest population in the settlements to be still covered assuming that a base station located in each site is a tower of a certain height, using a propagation model to estimate the coverage radius; a3) determining the settlements covered by the base station located in said selected site and removing said settlements from the settlements to be covered; a4) repeating steps a2 and a3) until there are no more settlements to covered in the given area.