The specification and drawing figures describe and illustrate a point-of-sale payment system. The point-of-sale payment system includes a mobile wireless communications instrument having at least one data processor. The data processor is capable of automatically selecting a payment instrument for transmitting a payment sum across a mobile wireless communications network and, if necessary, a credit network. The point-of-sale payment system may also include a data transmission subsystem for receipt, storage, processing, and transmittal of data across the wireless communications network and/or the data transmission subsystem.