edure and its processing load. Network IEEE, 16(6), 38-44, November/December 2002. With permission. first row a reference value of 100 has been assigned to procedure/scenario (5). The results show that the introduction of SIP security accounts for nearly 80% of the processing cost of a stateless server and 45% of a call stateful server. This increase can be explained with the increase in the number of exchanged SIP messages and with the actual processing cost of security. Salsano [21] estimated that 70% of the additional cost identified was for message processing and 30% for actual security mechanisms [23,24]. References [1] Hassan, H., J.M. Garcia, and O. Brun. 2006. In Proc. 2nd Interna- tional Conference on Communication and Information Technologies, 2006, ICTTA'06 2, Damas, Syria, pp. 3251-56. April 24-28. [2] Wu, J.S., and P.Y. Wang. 2003. The performance analysis of SIP- T signalling system in carrier class VoIP network. In 17th Interna- tional Conference on Advanced Information Networking and Applica- tions (AINA'03), IEEE. 39. Xi'an, China. March. © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security [3] Kueh, V.Y.H., R. Tafazolli, and B. Evans. 2003. Performance evalua- tion of SIP based session establishment over satellite-UMTS. Vehicular Technology Conference 2003 (VTC 2003-Spring). The 57th IEEE Semi- Annual, IEEE 22-25 2: 1381-85. Jeju Island, Korea. April. [4] Kwon, T.T., M. Gerla, S.K. Das, and S. Das. 2002. Mobility management for VoIP services: Mobile IP VS SIP. IEEE Wireless Communications 9: 66-75. [5] Curcio, I.D.D., and M. Lundan. 2002. SIP call setup delay in 3G net- works. Seventh International Symposium on Computers and Communi- cations (ISC'02) 835. [6] ETSI Telecommunications and Intranet Protocol Harmonization Over Networks (TIPHON), 2000. End to End Quality of Service in TIPHON System; Part 2: Definition of Quality of Service (QoS) Classes, TS101 329-2 v.1.1.1, July. [7] Handley, M., and V. Jacobson. 1998. SDP: Session Description Protocol, IETF, RFC 