Mosiuoa Tsietsi Alfredo Terzoli George Wells Prototyping a P2P SIP User Agent with Support for Multiple Overlays. 474-479 2008 PerCom http://doi.ieeecomputersociety.org/10.1109/PERCOM.2008.102 conf/percom/2008 db/conf/percom/percom2008.html#TsietsiTW08