Create and log into an account for the AT&T prepaid card at ATT.com to refill the prepaid card. Alternatively, visit an authorized retailer such as Target, Best Buy or Wal-Mart to add funds to the card.
AT&T prepaid cards fund GoPhones that do not require a contract like many other cell phones. Users must add funds to the cards before the expiration of the current refill. Expiration times vary depending on the value of the current purchase on the phone. Check card usage and funds remaining using the AT&T online account page or by calling AT&T customer service.
As of 2015, refill values from $10 to $24 expire in 30 days, from $25 to $99 expire in 90 days and refills above this expire in 1 year. Refills not made within this period can cause deactivation of the phone. Refills not made within 60 days of the card expiring, the GoPhone account can be deactivated completely and the account will have to be re-established.
Additionally, purchase and refill AT&T prepaid cards at Wirelessrefill.com. This site presents offers from AT&T. This site offers additional features for users, such as a cash back program, rebates and does not charge taxes for fees for using the site to refill cards.