A phone card is a small plastic card which resembles a credit card in shape and appearance. It is used for paying for calls and telephone services. It works through a Pin. Holding the card physically becomes insignificant if you remember the Pin number and the Pin is just sufficient to make a call through the card.

There are two types of prepaid phone cards. The standard card is the one which is discarded after being fully used up. The other alternative is the rechargeable card which can be topped up further and can be used again and again.

The stored value phone cards, which hold the balance of the card, work on the same principle as an ATM card. There are different ways of encoding the value on the cards. The earliest technology was through a magnetic strip that carried information. Further, another technology of optical storage was developed. More…