some info on security of P2P SIP

See Jan Seedorf, "Security Challenges for Peer-to-Peer SIP", IEEENetwork, September/October 2006.http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=36007&arnumber=1705882&count=6&index=5http://www.jcbroadband.com/Library/jcbvoip5.pdfHenning 

The quoted paper by Jan Seedorf, "Security Challenges for Peer-to-PeerSIP"http://www.jcbroadband.com/Library/jcbvoip5.pdfmentions briefly distributed trust and reward.Solid progress has been made as shown in "p2p Trust Infrastructure" byR. Nelson and Gruia Pitigoi-Aron, seehttp://www.cs.ucla.edu/~rlnelson/trust.pdf