| 摘要 |
A credit or phone card (10) has two items (12, 14) of information, one (12) initially readable and the other (14) initially unreadable, the store (10) being provided with means (16) operable by the user in an irreversible manner to render said other item (14) readable, the two items (12, 14) related to each other in a verifiable way that requires machine-stored information not on said card (10). The two items comprising e.g. digits are read through a telephone to a computer which verifies the relationship and then allows limited access to a facility whose value is deducted from a value stored in the computer corresponding to the purchase price of the card (10). The means (16) may be a scratch-off coating or the removal of a sealed envelope. <IMAGE> |
