"The 15005 response code means that the transaction was declined
by the cardholder's issuing bank. The buyer will have to call his or
her issuer for further information, as banking privacy regulations
prevent the issuer from sharing the decline reason with third parties. The recommended handling path for this error is to inform the buyer
that the transaction has been declined, he or she should contact his or
her credit card issuer for details on the reason the transaction was
declined, and that he or she should use an alternative funding source
for the transaction.
Note: Some cards may be blocked from online transactions, or even
cross border (international) transactions. We recommend credit card
holder to call the card issuing bank to find out the real reason."