1 -- Design of a Set-top Box (STB) is presented to provide virtual platforms such that it can support multiple service providers. Each service provider is able to manage its own multimedia streams and ensures the desired network performance for each flow and enables QoS in IP Multimedia Subsystem (IMS)-based networks. Simulations are done to assert the correctness of the algorithm. Keywords- IP Multimedia Subsystem (IMS); Set-top box; Platform Virtualization; end-to-end QoS