HOW IT WORKS

Pull off the serial cable between POS and receipt printer.
Between POS and receipt printer insert POS Connector.
Cashiers operate the POS in exactly the same way as cash payment.
POS Connector intercepts and parses the receipt data.
POS Connector sends the data to buyer's smartphone with built-in Bluetooth module.
POS Connector catches the total amount included in the receipt data.
The buyer's smartphone sends a payment completion signal to POS Connector.
When the connector prints 'paper receipt', payment is completed.
Bluetooth signals out without discrimination, so it's difficult to specify exactly which device to pay for.
Magnetic sensors are very sensitive to magnets, so it is easy to determine YES or NO.
The combination of BLE RSSI sensor and Magnetic sensor makes to implement the same user interface as NFC tagging.
In case of large payment of money the buyer can setup password option.
Buyer's smartphone gathers the receipt with JSON format automatically.
It provides the same user experience of 'Receipt printing = Payment completed'.
This solution can provide the 'Beacon service' like 'Smart Order' immediately.
The manufacturing prime cost of POS connector is nothing more than the price of one dish of pizza.
Acquire 'this solution' like the electronic toll collection systems.