> > Another method would be a standardised QR code so that you can make a transaction from your app by scanning the qr code. > Wouldn't work in a lot of places

> > Another method would be a standardised QR code so that you can make a transaction from your app by scanning the qr code. > Wouldn't work in a lot of places where there's no LTE reception, I happened to read about this recently (https://www.emvco.com/emv-technologies/qrcodes/ https://www.emvco.com/emv-technologies/qrcodes/), since it's going to be the base of Brazil's new instant payment system to be released later this year (PIX - https://www.bcb.gov.br/estabilidadefinanceira/forumpagamentosinstantaneos https://www.bcb.gov.br/estabilidadefinanceira/forumpagamento...). From what I understood, it does have a way to do offline transactions. There are two kinds of QR codes: one which is scanned by the app and used for both online and offline transactions, and a second kind used when offline which is presented by the app and scanned by the POS. This second QR code contains data similar to what a chip card would return to the reader during an offline transaction, so the transaction flow after that point is similar.