A method is provided for processing authentication of a consumer using one of a plurality of different types of payment instruments to conduct a commercial transaction over a communications network with a merchant. The payment instrument being used is either enrolled in or not enrolled in an authentication program conforming to one of a plurality of authentication protocols prescribed for the respective plurality of different types of payment instruments by payment networks supporting the same. The method includes: obtaining payment information for the transaction from the merchant, the payment information including a number identifying the particular payment instrument being used; determining the type of payment instrument being used from the payment information; obtaining an authentication determination for the transaction in accordance with the authentication protocols prescribed for the determined type of payment instrument being used; and, returning the obtained authentication determination to the merchant.