A contact center is a complex integration of computers, human operators (agents), telephone and packet networks, and their equipment. Contact centers can be classified into three types, depending of whether they handle inbound traffic, outbound traffic, or both inbound and outbound traffic, and their scale can vary from a few agents to thousands of agents. Figure 8.1 illustrates an example of a large scale contact center (``call'' center, in particular) that handles inbound calls .
Consider a customer calling a contact center via a toll-free number. The telephone company that provides the toll-free service connects the call via the public telephone network to a private automatic branch exchange (PABX) of the contact center. Here, the PABX is connected to the public telephone network through multiple telephone lines, called trunk lines. If there is a free trunk line, the call is connected to the PABX; otherwise, the caller receives a busy signal.
The calls connected to the PABX are routed either to an (interactive) voice response unit (VRU) or to an automatic call distributor (ACD), possibly depending on the dialed number and/or the caller's ID (number). If a call is routed to the VRU, the caller hears an automatic response and performs self-service by pushing buttons (dialing) or by speaking to the VRU. Some customers complete service at the VRU, and others who request connection to an agent are routed to the ACD.
An automatic call distributor (ACD) is a specialized router that is designed to route calls to individual agents at the contact center. At the ACD, various information is available both on the caller and on the agent, and the information is used to route a caller to an agent. The caller's information such as the caller ID and the record of interaction at the VRU may be used to identify the customer, and this allows the ACD to retrieve more information, such as their language, priority, and the type of requested service, from a customer data server. Agents log into the ACD at their terminals when they start working, and their login ID can be used to retrieve full information on types and levels of their skills. Computer-telephone integration (CTI) is a middleware that closely ties computer systems, including the customer data server and the terminals at the agents, and telephone networks. CTI enables sophisticated routing at the ACD. In addition, CTI can be used to automatically display a caller's information on an agent's workstation screen.
Based on the caller information as well as the information and availability of agents, the call may be connected to an agent, or may be held on in a queue. A waiting customer may abandon the call before being served, or may eventually be connected to an agent.