The security code (or CVV2 number) on your credit/debit card is a security measure we require for all transactions. Since a CVV2 number is listed on your card, but is not stored anywhere else, the only way to know the correct CVV2 number is to physically have possession of the card itself.
Most credit/debit cards have a three digit CVV2 number on the back of the card, after the card number in the signature strip. The CVV2 number is four digits on American Express cards, where it appears on the front of the card at the top right.
IF YOU CANNOT READ YOUR CVV2 NUMBER, YOU WILL HAVE TO CONTACT THE CARD ISSUER.