There is an increasing user demand for multimedia services, which have strong requirements in terms of network resources. Both requirements and network resources may vary during the service lifetime. Therefore an adaptation process is required to permanently make sure service requirements match network capabilities. To this end, we propose an architecture made of two decision entities, namely the Service Manager and the Mobility Manager. The inter-manager interface allows network resource use to be optimized, while providing services with the maximal available QoS, thus maximizing the user experience. We present related algorithms for single- and multi-homed terminals. Finally, the whole architecture was implemented in a testbed, which allows scalable video contents to be simultaneously streamed over multiple heterogeneous network connections.