Here are some things you should know before buying a prepaid phone card:

Confirm the rate: How much are you paying for a minute of conversation time? If the rates are not conspicuously displayed, read the packaging or promotional displays for an idea of the actual rates. Look for rates for both domestic and international calls. Don’t be swayed by ads that say only “50% cheaper”. The question is: “cheaper than what?”

Read about all the charges: Before you purchase the card, be sure to read the fine print about all the charges. These charges often include activation fees, access fees, weekly or monthly service fees, and additional charges for calling from a pay phone. Avoid buying prepaid phone cards that make no disclosures.

Do the math: After you have read all the fine print, do the math to figure out what you will actually be charged. The actual costs may be significantly higher than the advertised rates.

Is there a toll free customer service number? Check the packaging of the card for a toll-free customer service number. If you experience a problem, the number displayed on the card should be of assistance. Try calling the number before you purchase the card. A busy signal on the customer service line could be a tip off of problems to come.

Find out if there’s an expiration date on the card: Some firms issue cards without expiration dates, but many cards expire. You need to be sure the card you’re buying won’t expire within the time you plan to use it.

Make sure the card comes in a sealed envelope or has a sticker covering the PIN: Anyone who copies the PIN can use the phone time you’ve already paid for.

Will the Merchant stand by the card? Ask if the merchant will refund if the telephone service is unsatisfactory.

Ask around. You may have friends or relatives who have used the card. Some of the questions you might consider: Were they charged for a call when there was no answer or when the line was busy? Was there a minimum charge for each call? For example, were charges based on a minimum of three minutes even though the call lasted only 30 seconds? Was the access number not available because of a constant busy signal?

Buy a small denomination: If the carrier is a company you’ve never heard of, or you don’t know someone who can vouch for the card, buy a small denomination card first and see if you like the service.