The integration of different communication technologies is one of the key features in next generation networks. In the integrated network environments, it is expected that users can access the Internet on an “anytime, anywhere” basis, and with better quality of service (QoS) by selecting the most appropriate interface according to their needs. Although network integration enhances user experiences, it raises several challenging issues such as candidate network discovery, call admission control, secure context transfer, and power management for multimode terminals.