Introduction

Call centers provide phone-based services to customers or clients in the private or public sector. In the private sector, call centers are used in various Indus tries to manage relations between customers and the company. A call center is an important communication channel to acquire new customers as well as to support existing ones. This customer support may include all after-sales activities aiming at customer loyalty, for example, help desk services and the management of customer complaints. During the past few years the number of call centers and the number of agents has been growing rapidly, demon-strating the increasing importance of call centers.