Existing infrastructure for processing credit card transactions at point-of-sale (POS) devices is leveraged to provide secure and convenient payment with a mobile device. A mobile transaction infrastructure that is integrated with the credit card interchange network receives information from the mobile device and passes this information to a gateway provider or a payment processor. By combining information from both the mobile device and the POS device, this backend infrastructure can uniquely identify a transaction and appropriately charge an account associated with the user of the mobile device. The transaction may be matched with the mobile device be based on location, time, transaction charge, and/or other factors.