Provides call center simulators based on a quick uniformized continuous-time Markov chain model. Staffing and scheduling optimization in large multiskill call centers is time-consuming, mainly because it requires lengthy simulations to evaluate performance measures and their sensitivity. Simplified models that provide tractable formulas are unrealistic in general. This package implements an intermediate solution, based on an approximate continuous-time Markov chain model of the call center. This model is more accurate than the commonly used approximations, and yet can be simulated faster than a more realistic simulation (based on non-exponential distributions and additional details). To speed up the simulation, the Markov chain is uniformized and only its discrete-time version is simulated. Performance measures such as the fraction of calls of each type answered within a given waiting time limit can be recovered from this simulation. The CTMC model supports multiple call types and agent groups, but it assumes that calls arrive following a Poisson process, and service and patience times are exponential. For more information about the model, see \cite{ccBUI08a}. The main class for the simulator is {@link umontreal.iro.lecuyer.contactcenters.ctmc.BasicCallCenterCTMCSimMP}. It can simulate a call center with multiple periods by using one CTMC for each period. The {@link umontreal.iro.lecuyer.contactcenters.ctmc.BasicCallCenterCTMCSim} class, on the other hand, provides a simulator for a single period, using a single CTMC. Both simulators first generate the total number of transitions from the Poisson distribution, followed by the transitions. However, the {@link umontreal.iro.lecuyer.contactcenters.ctmc.IntMCallCenterCTMCSim} class implements a single-period simulator generating a large number of transitions and integrating over the number of transitions using Poisson probabilities when estimating performance measures. All these simulators use CTMC models represented by the interface {@link umontreal.iro.lecuyer.contactcenters.ctmc.IntMCallCenterCTMCSim}. The package provides two different implementations for this interface: one adapted for a single call type and agent group using linear search, and another one for multiple call types and agent groups based on indexed search.