Systems and methods are provided to facilitate online transactions via mobile communications. In one aspect, a system includes a data storage facility and an interchange coupled with the data storage facility that stores purchase receipts in association with phone numbers. The interchange includes a common format processor and a plurality of converters to interface with a plurality of different controllers of mobile communications. The converters are configured to communicate with the controllers in different formats and with the common format processor in a common format, to obtain a confirmation of a payment request that identifies a phone number, a merchant and a purchase from the merchant. After a confirmation is received, the interchange is to use funds associated with the phone number to pay the merchant for the purchase and to receive and store a receipt for the purchase from the merchant.