Streaming media from the Internet is a successful application for end-users. With the upcoming success of mobile devices and home networking environments, cooperation among users will become more important in the future. To achieve such cooperation, explicit middleware standards have been defined. However, many of them have been built for specific networking technologies, and interoperability is hard to obtain. We propose a new concept for cooperation exemplary for collaborative media streaming by using IETF multimedia session control protocols together with a proxy architecture. This concept is more scalable on any networking environment and provides for easy interoperability.