A call center or call centre (see spelling differences) is a centralised office used for the purpose of receiving and transmitting a large volume of requests by telephone. A call center is operated by a company to administer incoming product support or information inquiries from consumers. Outgoing calls for telemarketing, clientele, and debt collection are also made. In addition to a call center, collective handling of letters, faxes, and e-mails at one location is known as a contact center. A call center is often operated through an extensive open workspace for call center agents, with work stations that include a computer for each agent, a telephone set/headset connected to a telecom switch, and one or more supervisor stations. It can be independently operated or networked with additional centers, often linked to a corporate computer network, including mainframes, microcomputers and LANs. Increasingly, the voice and data pathways into the center are linked through a set of new technologies called computer telephony integration (CTI). Most major businesses use call centers to interact with their customers. Examples include utility companies, mail order catalogue firms, and customer support for computer hardware and software. Some businesses even service internal functions through call centers. Examples of this include help desks and sales support.