I have one of those old 3 slot pay phones. Many years ago my buddy was making an operator crazy (remember when Ma Bell had operators). A call from my house to his was a toll call and he tried to dial home on his credit card. The operator came on the line and said the card was bad. He told her he would just pay at the phone. She said this wasn't a pay phone. Then he started pumping in coins and the unmistakable sound of dings and dongs made her crazy. They bantered back and forth for about 5 minutes. She finally put the call up for free. A couple days later I got a call from the billing department telling me I was going to see an investigator or a charge on my bill. I just told them to bill me.