A generic representation of the telecommunications infrastructure in a metropolitan area designed to be integrated into a much larger simulation of the seventeen key infrastructures[1] has been implemented in Vensim[2]. This Critical Infrastructure Protection Decision Support System (CIP/DSS) is designed to provide insights for the Department of Homeland Security (DHS) in making decisions about investments related to critical infrastructure protection[3]. Although a system dynamics representation was well suited to representing the dynamics and interdependencies in this complex system of systems, it was recognized early on that collaborations with key infrastructure domain experts and organizations would be important to the success of the project. This paper summarizes the results of a collaborative effort with Bell Laboratories, Lucent Technologies to leverage a detailed switched network simulation to inform the telecommunications system dynamics model in CIP/DSS.