Telemarketing is the practice of businesses contacting prospects via the telephone for the purpose of selling them a product or service. Telemarketing can be to both people who are current customers or potential customers. Today there is legislation where people can register their phone number and not be contacted for the purpose of sales. Telemarketing companies are required to scrub against this list and not contact those that have registered. There are exceptions though which include: up until 90 days after you register you can be contacted (this allows companies to add you), if you phone becomes disconnected for any reason you must register, charities are exempt, and companies you have done business with in the past 18 months may contact you as well.