In this paper we present a hybrid discrete Particle Swarm Optimization (PSO) algorithm for the Mobile Network Deployment Problem (MNDP). First, we fully describe the MNDP, including a term for taking into account the Electromagnetic field produced by new locations of BTSs. We also describe the proposed PSO algorithm and some variations incorporated in order to cope with discrete search spaces, such as the one in the MNDP. We finally show the performance of the proposed discrete PSO in a real MNDP in a Spanish city near Madrid: Alcala de Henares.