Using a multi-layer approach to tackle the service interaction problem in telephony scenarios

The inauguration of IP telephony as a new and promising technology has opened the door to a variety of enhanced communication services and applications, which differ from those of the PSTN. The shift from circuit switched to packet-based networks, from a central to a more decentral organization, from professional and vendor driven development to an open development environment enables a multitude of opportunities. A variety of tools and methods for service creation has been developed to ease the process of design and implementing services. But these new freedoms hold new risks (well known from the PSTN area), which are currently not in the main focus of standardization. The rising problem can be overcome by the use of formal methods and checks which also tackle the important problem of feature interaction. In this paper we present a multilayer concept using a mixture of formal and informal techniques like service pattern to approach this topic.