Communication in next generation networks will use multiple access technologies, creating a heterogeneous network environment. To enable end-user terminals to move between access networks with minimal disruption, the terminals should be able to maintain multiple active network connections. Such a multihomed mobile host will experience different capabilities and coverage area depending on the access technologies. This paper proposes and evaluates an extension to Mobile IPv6 enabling multihoming, regardless of the access technology. Mobility of multimedia communication in this environment should adapt to changing conditions and be base on dynamic measurements and user preferences. The proposed architecture gives opportunities for mobile multimedia applications to use multiple access networks simultaneously and the possibility to move individual flows. Media flows are identified by destination IP address, protocol and port number. Results from a real world prototype are presented using three different wireless access technologies: 802.11, UMTS and 802.16-2004.