Mudhakar Srivatsa Ling Liu Arun Iyengar Preserving Caller Anonymity in Voice-over-IP Networks. 50-63 2008 IEEE Symposium on Security and Privacy http://doi.ieeecomputersociety.org/10.1109/SP.2008.10 conf/sp/2008 db/conf/sp/sp2008.html#SrivatsaLI08