A telephone card, calling card or phone card for short, is a small card, usually resembling a credit card, used to pay for telephone services. Such cards can either employ a prepaid credit system or a credit-card-style system of credit. The exact system for payment, and the way in which the card is used to place a telephone call, depend on the overall telecommunication system. Currently, the most common types of telephone cards involve pre-paid credit (stored-value) in which the card is purchased with a specific balance, from which the cost of calls made is deducted. Pre-paid phone cards are disposable. When the balance is exhausted you simply buy a new card. In some countries, cards purchased can be refilled. The other main type of card involves a card with a special PIN printed on it that allows one to charge calls to a land-line telephone account. These are known as remote memory cards. The cards are sold by telecommunications companies like GlobalTel.