The method for operating a hearing system comprises the steps of a) requesting (300) said hearing system to execute a functionality; and b) deciding (400) whether or not to execute the requested functionality. It preferably comprises the steps of c) checking (440) the current availability of the requested functionality; wherein the decision of step b) depends on the so-obtained current availability of the requested functionality, and d) executing the requested functionality, only if the requested functionality is currently available in said hearing system. The hearing system comprises at least one decision unit adapted to deciding whether or not to execute functionalities the hearing system is requested to execute.The invention can make it possible to form hearing systems from a wide range of devices.