In telecommunications, increasingly complex service systems evolve which have the objective to produce ICT services. The increased complexity is due to the convergence of the industry sectors information technology, telecommunications and media. Telecommunication network operators are challenged to modify their business strategies: they can not any more produce ICT services in a vertically integrated fashion but need to market preliminary services as suppliers for other ICT service providers. For this task, modular service concepts known from Service Science and IS research can be employed. ICT service modules, so called Enabling Services, are provided on Service Delivery Platforms to support service development. In this work, an Enabling Service conceptualization is developed. Based on a case study, a process for the specification of Enabling Services is presented.