Many service providers offer customers the choice of either waiting in a line or going offline and returning at a dynamically determined future time. The best-known example is the FASTPASS^® system at Disneyland. To operate such a system, the service provider must make an upfront decision on how...

We study cross-selling operations in call centers. The following questions are addressed: How many customer-service representatives are required (staffing), and when should cross-selling opportunities be exercised (control) in a way that will maximize the expected profit of the center while...

This paper employs sample path arguments to derive the following convexity properties and comparative statics for an M/M/S queue with impatient customers. If the rate at which customers balk and renege is an increasing, concave function of the number of customers in the system (head count), then...