My mother her sisters did something similar. They lived about 20 miles apart and if they wanted to go visit they would call and let the phone ring 3 times. If they were going to be home they would call back and let the phone ring 3 times.
I had a friend of mine who lived on the other side of town. His family couldn’t afford a phone. There was a small neighborhood store near his house and it had a pay phone in a booth outside. He would put a dime in, dial my number, let it ring once then hang up. He’d get his dime back. I knew it was him because of the one ring and I would call the pay phone to talk to him.
As kids we would hitchhike, backpack, stay in your hostels etc.
We'd make a collect person to person call home to a fictitious person to check in and do a wellness check - obviously hanging up as the fake person was not there. If we really had a problem we'd obviously go collect to a real person.
Often we would have western union money sent to a town we planned to be in soon. We also had main delivered "posta restante" ahead of where we were going and picked up the letters when we got there.
And to stay on 'joke" topic...