>Anecdotally, fence phones were still being used throughout the 1970s and perhaps even later. C.F. Eckhardt describes calling his parents who lived in rural Texas and still used a fence phone; their number was simply 37, designated on the small local network by three long rings and one short ring.

Is this perhaps an OCR or typography error? If the number were "31" that would make much more sense to encode as three long one short. A stylized 1 can look a bit like a 7 depending on how the characters are drawn.