I haven't used pay phones in years. One of the issues I ran into was poorly maintained equipment, would often be able to make a call but the other end couldn't hear me due to crap in the mic end of the handset but still would get charged for the attempted calls anyway.
Then they started disabling the keypad after the call was complete. So you would dial your calling card company and when it was time to plug in the card number it wouldn't work.