This paper presents the research activities carried out within the scope of the Liaison project. Most of the work has been performed on WiFi location. WiFi is nowadays widely deployed in buildings such as hotels, hospitals, airports, train stations, public buildings, etc. Using this infrastructure to locate terminals connected to the wireless LAN is expected to have a low cost. Methods presented in this paper include fingerprinting and tracking through particle filter constrained on a Voronoi diagram and TOA based on data frames and acknowledgments at the link level. Other technologies have also been researched: A-GNSS to handle the transition between outdoors and indoors, UWB in ad-hoc mode to cope with possible lacks of infrastructure and inertial MEMS to increase the availability and robustness of the overall system.