The roll out of 3G networks coincides with the emergence of a variety of wireless access technologies (IEEE802.11x, Bluetooth etc.) supporting high bitrates in restricted areas and acting complementary to wide coverage mobile networks. Integration of the different wireless access technologies is the general trend towards 4G. Our work focuses on the area of handover management in the context of 4G, and specifically on the initiation and decision phases of the handover mechanism. In 3G or earlier generation networks, handovers are initiated and decided by the base station on the basis of measurements of perceived SNR, cell congestion, terminal speed etc. In 4G, due to the diversity of available radio access services additional factors need also to be taken into account. We propose an agent-based architecture that determines the timing and target network of handovers with respect to user, application and terminal constraints.