Announcers like Jimmy Deer at WDAK (Columbus) wrote and performed scripts advertising goods and services.
At its very beginning, radio did not host advertisements. Soon, though, stations needed to find a source of revenue separate from those newspapers and universities that ran them. To do so, stations turned to “sponsors.” Companies could buy slots of time, generally in 15, 30, or 60 minute increments, that they would sponsor. The company would be in charge of filling that slot with whatever kind of programming they wished. The advertisers had complete control over the radio schedule and content.
Radio was the only form of media that used this type of sponsorship for advertising. However, by the 1950s, stations began taking back control of their programming. They transitioned to a “magazine plan” of advertising, in which specific short slots of advertising were sold within a program. In this plan, the station, not the advertisers, had control over the content and schedule of their stations. This should seem familiar, as it is the way most radio advertising is done today.