On detecting feature interactions in the programmable service environment of Internet telephony

This paper presents a new method to tackle the feature interaction problem in Internet telephony with the CPL (Call Processing Language) programmable service environment. To cope with the problems of the programmable service, we first propose a notion of semantic warnings, which are guidelines for non-experts to assure semantic correctness of individual CPL scripts. Then, we define feature interactions as semantic warnings over multiple CPL scripts. On the basis of this definition, we propose a method for detecting feature interactions. We conduct an experimental evaluation with an open-source VoIP system. The results show that the proposed method identifies a semantic redundancy in a ready-made feature and five interactions among pairwise combinations of the features. We also discuss the applicability and limitations from the viewpoint of implementation.