Event driven service (EDS) is one of such services administrating different functions of multiple service providers according to the user situation. This paper first describes the service model of EDS, a User-centric Service for multiple service provider environments over the next generation networks. The multiple provider environments stimulates the unified identifier management, namely unified identification (U-ID), to enable users to be provided network services without awareness of multiple providers. Combining these two concepts, i.e., EDS and U-ID, the designed structure of EDS with U-ID and related procedures are given. Finally, the implementation results tested on Korea Advanced Research Network (KOREN) are described.