Invalid zip code error is displayed when attempting to process a payment from a customer with a billing address outside the U.S.
If you have a customer who has an address located outside the United States, they may have a postal code (or Province code) that includes characters that do not meet the U.S. 5 digit standard.
In most cases the international card holder is provided with information by the card issuing entity regarding how to process in the United States when they are presented with this situation.
For transactions that have problems due to such a zip code situation, the card holder will need to contact the card issuing bank to determine if there are options for using their international card with U.S. based businesses that require a 5-digit numeric zip code. It is the responsibility of the card holder to provide such information when processing an international card.
If proper information has been obtained but there is a question whether a card is being declined due to being an international card, A Voice Authorization may be performed for verification and captured in the Online Service Center if successful. However, if the card fails the voice authorization, the card holder will need to speak with their card issuing entity for more information and submit a different form of payment.
Any attempt to enter information by you, the merchant, other than was provided by the card holder will violate the Card Processing Rules and Regulations as well as provide a valid reason for a customer to dispute the charge, since the zip code is inaccurate and you were the one who altered the original transaction data.
NOTE: Point of Sale (POS) merchants may need to adjust the security settings within the POS software before processing appropriate international cards.