Abstract— This paper describes the implementation and deployment of a novel architecture for a metropolitan open wireless access network, shared among different service providers. A layered model that differentiates four different actors (user, Wireless Island, Neutral Operator and Service Provider) is introduced, and the mechanism to allow Service Provider selection by the user is detailed. Other key technical issues like AAA, security, redundancy and scalability are also analyzed. This testbed has been used to provide Internet access to different user communities related to our University and as a experimentation platform for service deployment and testing in a real-life scenario.