Here are a couple of 12" records featuring commercials for radio airplay which I came across recently. The first contains 15 ads, each approximately 45 seconds long, for Alcoa Wrap. This product seemingly does just about everything - at least according to spokeswoman "Ann of Alcoa". In each ad (eight of them on side one, 7 more on side two), the phone rings, and Ann answers, then helpfully leaves a few seconds for the radio announcer to ask whatever the appropriate question was (undoubtably on a cue sheet provided, although I don't have it), before she answers the question with the rest of the commercial.
Then there's this curious record, from the Maine Sardine Council. As much as I love sardines (and I do), I can't say I've ever had a sardine sandwich, or even that I've seen one listed on a menu. Wherever these conversations take place, however, sardine sandwiches seem to have been all the rage. This record contained 12 tracks, but these consisted of the same four, 30 second ads, each repeated three times.