Payments being made using a gift card are handled in the same way as credit cards. The only difference is that the “Gift Card” payment method is used instead of the type of credit card. The gift card payment is processed immediately, and will either be approved, partially approved for the available balance or declined if there are no funds available.
Remember that using a gift card as a payment requires an immediate card swipe to check the available balance on the card. At the end of the sale, you will need to swipe both the credit card and gift card. The two cards must be swiped in the same order in which the payments were entered. Be sure to pay attention to the Transaction Details area near the top of the Worldpay window, to ensure that you are swiping the right card (i.e. Credit or PrePaid).