Compare price. Many prepaid cards are priced per minute and you can fill up the card in dollar amounts. Depending on where you want to call to or from, the price per minute will vary. Locate the best-priced plan.
Find out how easy the card is to renew. If you'll be using the card on a regular or semi-regular basis for any period of time, you want a card that's easy to put more money on. A card that requires you to have Internet access to log in to an account where you transfer credits to the card will be more of a hassle to deal with then a card that you can simply transfer credits to over the phone.
Compare calling ranges. Note the countries you'll be calling from and/or to and see if the card covers that range. Different cards cover different levels. For example, you can purchase a card on which you can call from the United States to Europe, but to call to or from Brazil may require a different card and plan.
Find out if there's a limit to the number of minutes you can place on one card. If you feel you'll be using the card extensively over a period of time, a card that has a high minute maximum would be better than a card that only holds 100 minutes or less.
Consider if you want a prepaid or a monthly card---both options are available. Prepaid cards offer credits, where you purchase minutes to transfer to the card. Monthly cards are generally for extended periods outside of your home country that give you a set amount of credits for a set rate per month. Credits are added to your card each month per the billing cycle.
