This article generalizes the models in Guo and Zipkin, who focus on exponential service times, to systems with phase-type service times. Each arriving customer decides whether to stay or balk based on his expected waiting cost, conditional on the information provided. We show how to compute the throughput and customers' average utility in each case. We then obtain some analytical and numerical results to assess the effect of more or less information. We also show that service-time variability degrades the system's performance. © 2008 Wiley Periodicals, Inc.