In 1997, the SDL-pattern approach was introduced to the scientific community. Since then, the approach has been improved in many ways. In particular, the pattern pool has been extended to cover a variety of distributed systems and communication protocols, a notation to define patterns has been added, and the methodology for pattern-based system design has been refined. Based on the results of more recent case studies, the approach has been assessed as consolidated, and is currently being transferred to industry. In this paper, we present our experience of applying the SDL-pattern approach in an industrial environment, the development of a UMTS call processing system, a part of the Radio Network Controller (RNC). Furthermore, the benefits of applying the approach are evaluated in this context and quantified.