Mastercard offers merchants two ways to process payment card transactions. With the dual message system, the merchant sends an authorization request with the first message and requests settlement with the second message.
The dual message system is most commonly used for transactions with signature confirmation, both physical signatures for card-present transactions and electronic signatures for card-not-present transactions.
The dual message system differs from the single message system which sends both the authorization and settlement requests with a single message.
The single message system is most commonly used for transactions with a PIN confirmation, such as card-present and ATM transactions.