A form of direct marketing that combines aspects of advertising, marketing research, and personal sales, telemarketing uses the telephone to reach customers or prospective customers.

Telemarketing developed massively through the 1990s through the combination of technology-led development of consumer databases, telephone communications, and creation of call centers. A call center is a central operation from which a company operates its inbound and outbound telemarketing programs. Inbound telemarketing refers to the reception of calls by the order desk, customer inquiry, and direct response calls often generated through the use of toll-free numbers. Outbound telemarketing, on the other hand, refers to calls that a company makes to customers to develop new accounts, generate sales leads, and even close a sale.

The primary advantage of telemarketing is that it can complete a sale for less cost than is needed to complete a sale using such techniques as face-to-face sales calls or mass advertising. However, for this method to be effective, proper training and preparation of telemarketing representatives needs to be as comprehensive as it is for personal selling. Planning the message is as important as the medium itself. A drawback to telemarketing is the fact that consumers react negatively to it. The majority of the public considers telemarketing calls unwelcome and intrusive, and they are ranked as one of the least desirable sales techniques. Despite this, organizations believe that the advantages of telemarketing, such as call reach and frequency and cost efficiency, outweigh the disadvantages.