From a phone booth (you have seen them in movies) you deposit a coin. It started as a "nickel" or 5 cent piece, then a dime or 10 cent piece and finally a quarter or 25 cent piece. You would dial "O" for the operator and ask to call a certain number collect. The call would be paid for by the person on the other end of the line. Best use for parents and family. You got your coin back.
Person to person was a bit trickier. You deposited your coins and asked the operator to act as a go-between and ask for a specific person. If that person was there, you had to pay the charges in advance. The trick was to ask for yourself. Then you left a message that you would call back at a certain time. That told them when you would arrive. You got your coins back.
No not that party line. There might be as many as ten people on a single line. The number of rings indicated your code to pick up. Nosey people would listen in on other peoples calls. There was an emergency signal that told everyone to pick up in case of disaster, escaped criminals, roving mountain lions or bears. Privacy was unheard of.