††The phone card was one of the first kinds of 'smart card' to be introduced.
It enables people to pay in advance for their calls in public telephones by buying a card for the appropriate amount.
The card is able to keep account of how much of its value has been used through calls, until the money originally paid has expired. After use the card is discarded.
Future phone cards are likely to be reusable to prevent the current waste of plastic. Such a card would be taken to a designated point, to be electronically "loaded" with the required number of units.
