Instant PINs, virtual calling cards and instant phonecards are an everyday reality. These are mostly credit card based and are predominantly delivered over the internet. They are nearly always pre-paid and come mostly in low denominations. In each case no plastic card is delivered and you will recieve a set of access numbers and identity or PIN codes. These cards normally are a one off purchase and expire. You need to buy a new one which will come with new codes if you wish to use the same calling card vendor again. Typically the time based phone cards come in increments of 100, 300, 600, or 1000 minutes. Dollar based phone cards start at $5 and go up to around $300. When you make a call, the total cost of the call (which is often made up of several components) is accumulated and the remaining value on the card is reduced by the cost of the call.
In a slightly different form, this technology has become so sophisticated that it is now possible to buy a prepaid card which is actually a miniature disposable cellphone. This card comes preloaded with airtime and when the time is used up the card is discarded.This form is particularly suited to foreign travel where you can make use of the local mobile phone system at local rates for short duration.
