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30 Security Issues in VoIP Telecommunica... > Acknowledgements - Pg. 787

CHAPTER 30 Security Issues in VoIP Telecommunication Networks 787 We further explored user lookup performance under heavy network traffic. We attempted to build as many connections as possible by simul- taneously launching user lookup traffic on 97 nodes in OpenVoIP and SW-VoIP, respectively, based on real-life call logs. The traffic generated include messages issued not only from those 97 users but also from an additional 52 users in the P2P VoIP network, as shown in the figure of user call degree distribution. We assume that these 97 users in SW-VoIP are divided into four clusters as in earlier described experiments, and a con- gestion avoidance mechanism has little effect on the average link traversal of our SW-VoIP com- munications. We compared two systems by eval- uating user lookup delay under up to 10,000 simultaneous messages. It is observed in the following figure that not only does SW-VoIP have less of an average delay than OpenVoIP but the delays in SW-VoIP also increase much less than the VoIP users' basic trust that their VoIP calls will reach the intended callee only. We further show that such unauthorized call diversion could lead to a brand new attack on VoIP users. For example, the voice pharming attack, which could trick the most cautious VoIP callers into giv- ing out sensitive information (SSN, credit card number) to the adversary. Also, our experimen- tal results show that millions of subscribers to leading commercial VoIP service providers such as Vonage and AT&T are vulnerable to vari- ous billing attacks, and the billing of existing SIP-based VoIP services is not trustworthy. The results show that existing VoIP users are suscep- tible to identity theft and financial loss due to the lack of the trust in currently deployed VoIP systems. Considering the rapid development of P2P- based telecom networks, many open issues remain to be solved. To date, P2PSIP is still