Two-stage SPIT detection scheme with betweenness centrality and social trust

Detecting SPIT (Spam over Internet Telephony) is an urgent demand with growing voice communication services. Chaisamran et al. proposed a trust-based SPIT detection scheme and it is superior to other trust-based schemes since it is valid for unknown users. However, this scheme might misdetect a call from low-frequent users as SPIT gradually in time, since they seldom call and thus their social trusts get decreased with time. In this paper, we propose a two-stage SPIT detection scheme using BC (Betweenness Centrality) and social trust to decrease misdetection of a call from low-frequent users as SPIT. BC indicates user's centrality in the entire network and the value of BC against legitimate users gradually increases with time even if users seldom call, whereas it does not increase against spammers since the connection between a legitimate caller and a spammer is hardly established. As a first stage, we use BC as a feature to correctly identify a call request from a low-frequent user. Then we judge whether a call is from a legitimate caller or a spammer by using social trust. By the computer simulation, we show that our scheme improves the false positive rate while maintaining high true positive rate.