I also remember before mobile phones at about 14 I would call my parents from the pay phone reverse charge and instead of saying my name and where I was calling from, I would say pick me up from the beach ect then my parents wouldn't accept the call but come and get me. It was a sneaky way of not using 50c to spend at the shop.
Dh would be forever calling me from pay phones when we first started "going out" to get some privacy we were 16 as my cord phone would reach to my door of my room but the cord had to go under the door. He bought me my first mobile at 17 and we were both with the same provider and the first 20mins were free so at 19 mins we would hang up and then ring back again we would do it for properly 2hrs every night. We are 30 now.