I remember calling into a few stations, too, and if the person or DJ actually running the program didn't pick up, they came to the phone right away... and I was always rewarded with patience, understanding of the question, and answers.
Holy moley, what did I just say? When does that happen today, in just about anything?
A couple that immediately come to mind:
KCRW-FM, about something I thought was wrong with a classical recording they were playing. That one was really interesting, as it resulted in me being permitted to make a visit to the station to personally examine the recording in question.
KFAC-FM, "the" L.A. classical station, regarding transmission issues with the Metropolitan Opera broadcasts that used to travel - not always reliably - over the nation's telephone lines back in the day.