Abstract : In next generation networks, the availability of different wireless access networks in combination with the evolution of mobile terminals with multiple access interfaces makes the handover decision problem an important issue to study in order to improve the vertical handover process. To allowing the best connectivity to applications anywhere at any time, many vertical handover decision strategies have been proposed in the literature. In this paper, we present an overview of the most representative and recent strategies. We also compare them. Finally, we introduce our context aware vertical handover decision approach based on both quality of service and energy-efficiency criteria.