If I remember correctly, making a collect call through your telephone company required talking to an actual operator who would set up the call and inform the receiving party of who was calling. The 800 number collect call services that eventually sprung up all used automated systems and they were perfect for this kind of abuse. You had about ten seconds to blurt out your message before the recording would stop.

I used to ride the Greyhound to visit my dad on weekends, and it would stop at a truckstop about ninety minutes away from my destination. At first I had to carry a pile of quarters to make the long distance payphone call to let him know I was on my way, until we finally figured out I could just blurt "Dad I'm in town xyz, be there in 90" instead of my name. Saved me a buck fifty or so every trip.