This paper proposes a novel mobile community service platform that enables a mobile phone to promote collaborations that are more advanced. Our research contributes in two folds. First, as a service design framework, a model of a mobile community is defined in which each member has a role and corresponding task to achieve a common goal. Second, the proposed platform provides a running and development environment based on the community model. It consists of a Community Service Phone Platform, a Community Server, and a Task Framework. The Task Framework provides programming interfaces that alleviate the task development overhead and enable plug-and-playable tasks. The phone platform is middleware and provides a running environment for the tasks.