The authors introduce a tool, called Ensemble, which uses algorithms and heuristics to analyze large circuit switched networks. This tool could be used to address the following topics: the quantification of interference when an established circuit blocks some other connection requests; how the routes used affect the performance of the network; how much one should charge each connection to maintain a predetermined revenue; the effect of a load change in some connection requests on the overall network and how one should change charges accordingly; and how one should compare network efficiency given a choice of alternate routes.<>