. However, it has been demonstrated that none of the existing SIP security mechanisms can satisfactorily deal with all security requirements. Conseque- ntly, SIP providers should also monitor the new developed SIP security mecha- nisms, in an attempt to explore ways for combining them with existing security measures. References [1] Bates, R. J. 2002. Broadband Telecommunications Handbook. 2nd ed. New York, USA: McGraw-Hill Professional. [2] Sicker, D. C., and T. Lookabaugh. 2004. VoIP Security: Not an After- thought. QUEUE ACM, September. [3] Geneiatakis, D., T. Dagiuklas, G. Kambourakis, C. Lambrinoudakis, S. Gritzalis, K. S. Ehlert, and D. Sisalem. 2006. Survey of security vul- nerabilities in session initiation protocol. Communications Surveys and Tutorials IEEE 8(3): 3rd. Qtr. 68-81. [4] Butcher, D., X. Li, and J. Guo, 2007. Security challenge and defence in VoIP infrastructures. IEEE Transactions on Systems, Man and Cyber- netics, part C: Applications and Reviews 37 (6): 1152-62. November. [5] VOIPSA. 2005. VoIP Security and Privacy Threat Taxonomy, Pub- lic Release 1.0. Available online: http://www.voipsa.org/Activities/ taxonomy.php, October. [6] Sisalem, D., J. Kuthan, and S. Ehlert. 2006. Denial of service attacks targeting a SIP VoIP infrastructure: Attack scenarios and prevention mechanisms. Network, IEEE 20 (5): 26-31. September-October. [7] Rosenberg, J., H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Spark, M. Handley, and E. Schooler. 2002. Session Initiation Protocol. RFC 3261, June. [8] Hersent, O., J. P. Petit, and D. Gurle. 2005. IP Telephony Deploying Voice over IP Protocols. New York, USA: John Wiley & Sons. [9] Spencer, M., B. Capouch, and E. Guy. 2007. F. Miller, K. Shumard ed. IAX2: Inter-Asterisk eXchange Version 2. Internet Draft, April. [10] Ferguson, N., and B. Schneier. 2003. Practical Cryptography. New York, USA: John Wiley & Sons. © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security [11] Shannons, M. L. 1998. Phone Book: The Latest Hig