We owned a group of small market stations in the late 70s til '85 when we sold it all.
We limited the geography the agency covered to a bit away from the central coverage area. We found places 10 years later still with the radio they used in the promotion
They did what they promised. They sent a group of salespeople to this market and really SOLD at an inflated rate, We got LOTS of business - revenue from 100 places that never advertised before. Few complaints. A few longer term clients resulted from their original promotion.
A few years after this promotion we improved on their idea, (did it ourselves) opening our own 1 woman straight commission phone sales department, (ala Moberly, Missouri....use Google) selling sports boosters, etc. at a BARGAIN rate, and "cut out the middleman."
Regular easy, great revenue. Everybody was smiling.