"Many hvacr contractors are turning to telephone 'on-hold' advertising as an effective, inexpensive way to market products and services to a captive audience.

Listeners on the other end of the line will hear about spring clean-and-check specials, financing on a new air conditioning system, or air cleaners to help them with their allergies."
—John R. Hall, "Commercials on hold are music to the ears of hvacr contractors," Air Conditioning, Heating & Refrigeration News, May 31, 1999