Warteschlangensimulator is a free, platform independent, discrete-event, stochastic simulator which allows to model queueing systems in form of flowcharts.
Callcenter Simulator is a free, platform-independent program for the analysis of staffing requirements in a call center. The simulator uses event-oriented, stochastic simulation for the computation of the parameters.
Mini Callcenter Simulator simulates a call center and takes into account many parameters not covered by the Erlang C formula.