This security workship is the third following successful events in Dallas 2004 and Washington 2005. The workshop addresses the challenges, advanced technologies and regulations for providing secure VoIP services over the Internet as well as in third generation networks. The 2006 workshop will extend the scope of VoIP security to IMS services and present the latest advances in denial of service and SPIT detection and protection mechanisms. The format of the workshop is based on two-day single-track sessions, with presentations of invited and regular papers from academia and industry.