You can drop your coins into the phone before picking up the receiver. Put in more than you think you'll need for the call, because when your time is up, you'll be disconnected. When you hang up, push the coin return to get your unused coins.
Some phones only accept phone cards Ask for a carta telefonica .
Rip off the perforated corner as indicated, and insert the card in the upper slot of the box on the right side of the telephone. Throughout your call, a digital display on the phone shows how much credit is available. When the card is used up or when you hang up, the machine ejects the card through the bottom slot. You ask the attendant or cashier for a line, and after you've finished, they tell you how much to pay. There is also a pay phone booth just outside our studio building which accepts phone cards.