A method of processing of a transaction between a first and second party is provided. The first party accepts payment via a plurality of different payment options selectable by the second party, and the plurality of different payment options are associated with a plurality of different authentication protocols prescribed therefor. The method includes: receiving payment information over a communications network at a server operatively connected to the communications network, the payment information identifying a particular payment option used by the second party for the transaction, and the server being equipped to format and route messages over the communications network in different manners to accommodate the plurality of different authentication protocols; determining from the payment information received at the server which of the different authentication protocols is prescribed for the type of payment option identified in the payment information; selecting, in accordance with the determination, a particular authentication protocol from the plurality of different authentication protocols supported by the server; obtaining an authentication determination for the transaction in accordance with the selected authentication protocol, including formatting messages and routing the formatted messages over the communications network in accordance with one or more mandates of the selected authentication protocol; and generating a one-time number to be sent back to the first party.