Abstract: A method for processing a payment relating to a transaction between a debtor and a creditor. The method includes displaying an amount of payment, and transmitting an authorisation message between a first node associated with a payment service provider system and a second node associated with a debtor instrument on a second network. Each node is separately and securely identified by a node identifying code. The authorisation message communicates an authorisation code. In verifying, a response message on a first network is transferred from the payment service provider system to a creditor instrument, when the payment service provider system receives the authorisation code in association with a debtor identifying code.