Eric C. Noel Carolyn R. Johnson Initial Simulation Results That Analyze SIP Based VoIP Networks Under Overload. 54-64 2007 conf/teletraffic/2007 International Teletraffic Congress http://dx.doi.org/10.1007/978-3-540-72990-7_9 db/conf/teletraffic/itc2007.html#NoelJ07