This paper describes the implementation of an indoor location system on a mobile phone for the Faculty of Electrical, Electronic and Telecomunications at the Universidad Nacional de Ingeniería, Peru. The proposed system makes use of WiFi signals and the Bayes filter in order to predict the user location. The principal advantage of the proposed method in comparison with similar methodologies is that our system does not need additional hardware or special equipments. As the experimental results show, the system achieves 92.31% for position accuracy and works in real-time. In addition, the proposed methodology could be used for similar location tasks.