Queueing Models for Call Centres

From a business point of view, a call centre is an entity that combines voice and data communications technology to enable organizations to implement critical business strategies or tactics aimed at reducing costs or increasing revenues. At an organizational level, cost are highly dependent on capacity management of human and technical resources. By utilizing methods of operations research and especially of queueing theory, this thesis will arrive at new models and extend existing ones. Current models are often restricted to a very simple set of operations, e.g. call centre agents toggle only between an idle and a talking state. It turns out, that these simplifications do not reflect reality in an appropriate way. Considering the given example, an after-call-work time may be introduced after the talk time. Obviously there is a high impact on the capacity of the system resources, as in after-call-work time the agent phone is not occupied. Furthermore it turns out, that a single view is not sufficient and models have to be splitted in a technical (system oriented) and a (human-)resource layer, both clearly highly interactive. My thesis will also consider and extend existing works from Zeltyn/Mandelbaum (Technion Israel), Stolletz (TU Clausthal), Whitt (AT&T Labs) and Koole (VU University Amsterdam), which form the academic base for analytic call centre engineering. On occasion, recent queueing models such as phase type queues will be incorporated.