Back then they had the crank generator inside the phone to create the charge needed, that’s why some people fished with them.

Bonus was if you couldn't make a call you knew your cows were out

Well if you can google it then it must be true.

Back in the late 50's my brother-in-law and friends heard about fishing that way. My grandmas old phone was still on the wall in her summer kitchen which was falling down. My brother-in-law went and got it and him and his friend took it to a lake and tried it out and had good luck but dark crept upon them. They went to town where they had met. My brother-in-law got out and in his car and they had intentions of going again the next morning so my brother-in-law told his friend (Mike) to just keep the phone in his car. My brother-in-law went to meet Mike the next morning only to find out he had hit the end of a bridge abutment going home and had been killed.
My brother-in-law went to where the wrecked car had been towed to with the expectation of getting the phone, but someone had stolen it !

Still do! (don't ask).