Abstract: Conducting payment card transactions through a payment network through a card reader with a merchant authentication code attached. A payment is processed in connection with a transaction using a payment card. Prior to approving the transaction, the payment card holder is contacted and requested to provide the merchant authentication code. If the merchant authentication code provided by the payment card holder is consistent with the merchant authentication code affixed to the device, approving the transaction. The merchant authentication code may be text, a bar code, a quick response code, a hologram or other code. The merchant authentication code may include information regarding the merchant such as location, business name and the like.

Abstract: Conducting payment card transactions through a payment network through a card reader with a merchant authentication code attached. A payment is processed in connection with a transaction using a payment card. Prior to approving the transaction, the payment card holder is contacted and requested to provide the merchant authentication code. If the merchant authentication code provided by the payment card holder is consistent with the merchant authentication code affixed to the device, approving the transaction. The merchant authentication code may be text, a bar code, a quick response code, a hologram or other code. The merchant authentication code may include information regarding the merchant such as location, business name and the like.

Abstract: Conducting payment card transactions through a networked device of a user wherein the networked device comprises a card reader and a wireless application operated by the networked device. The transaction may comprise acquiring information from a client's payment card using the card reader; providing such information from the card reader to the networked device through a headphone or similar jack; and processing the data through the mobile application connected to a payment network. More specifically, the networked device transmits a known first signal to the card reader, the card reader returns a second signal which is a function of the first signal and a third signal generated by the card reader that is indicative of information stored on a payment card, and the networked device derives the third signal from the first signal and the function applied to the first signal and the third signal.