From a practical point of view, the calibration of micro-simulation route choice parameters is a complex work. It is mainly the case in urban networks where the link travel time variability due to traffic lights and the high number of path possibilities make the traffic flow stability difficult to reach. This prensentation starts with a brief theoretical approach of route choice models and then underlines the specific problems of urban networks calibration. Some examples based on the Lausanne city network model are also shown. At the end, a discussion is open about the pertinence of the route choice models based on the user-equilibrium models. Indeed, different studies and practical experiences emphasize that the user knowledge of the different path possibilities and the currents traffic conditions are not as good as supposed by these methods. Finally some conclusions are displayed at the end of the presentation.