How to use a computer as a telephone?

The user of the booth pays for the call by depositing coins into a slot on the telephone, by entering a payment code on the telephone's keypad, or by using a telephone card. Coin-operated phones usually take the money before the call is made, and return it if there is no answer on the receiving end. Other phones, such as those used in the UK until the early 1980s, take the money after someone has answered at the other end by blocking the call until money has been deposited. Some pay phones are equipped with a card reader that allows a caller to make payment with a credit card. A caller who possesses no means of payment may have the phone company's operator ask the call recipient if the recipient is willing to make payment for the call; this is known as "reversing the charges" or "calling collect". It is also possible to place a call to a phone booth if the intended recipient is known to be waiting at the booth, however not all phone booths allow incoming calls. Long before "computer hacking" was a common phenomenon, creative mischief-makers devised tactics for obtaining free phone usage through a variety of techniques, including several for defeating the electro-mechanical payment mechanisms of telephone booths--early methods of phone phreaking.