Perhaps this thread[1] is useful, as well as these links[2][3][4] contained within? 1. http://archives.seul.org/or/talk/Aug-2006/msg00232.html 2. http://www.schneier.com/blog/archives/2006/08/skype_call_trac.html 3. http://ise.gmu.edu/~xwangc/Publications/CCS05-VoIPTracking.pdf 4. http://www.secdev.org/conf/skype_BHEU06.handout.pdf