A system is disclosed for marketing merchandise or services by telephone using brief prerecorded audio demonstrations stored in an audio program repeater and connected to a customer's telephone line by a switching system under control of a data processor in response to a code entered by a customer service...http://www.google.com.au/patents/US4071698?utm_source=gb-gplus-sharePatent US4071698 - Telephone system for audio demonstration and marketing of goods or services
