Users' needs are the driver of the next generation of telecom services. Founding the services on users' needs requires that various services cooperate together to meet specific needs. As a consequence, services should no more be developed as "silo" but with composable service enablers. This enabler paradigm raises the issues of the identification of the enablers and of the consistency of a service composed from various enablers. These issues must be addressed by considering the service from the user point of view: what is the added value for the user and through which perceived steps is this added value provided? Such service business processes are then a key tool to identify enablers and to ensure the coherence of composed service.