Modeling overloaded VoIP systems

Since 9/11 many telecommunications systems have seen the need to deal with overloading during high traffic conditions. As the use of VoIP increases an important question that needs to be answered is: "Can the voice packets be delivered in a timely fashion when the there has been a significant increase in traffic?" In this paper we considered the problem of modeling VoIP systems in an overloaded condition. We look at the problem from a simulation and analytic point of view. We present analytic models for the packet latency and jitter and loss probability for the three prevelant disciplines being used for VoIP today: First Come First Served, Priority Queue and Weighted Fair Queueing Systems. In addition, we investigate how simulation languages like GPSS/H compare with respect to runtime with simulation models developed using Visual Basic for Applications and if their runtimes are acceptable for practical use.