Can I make NFC payments using Google Pay while in airplane mode, like when I don't have cell phone or wifi service (particularly when travelling)?
The payment system of Google Pay uses tokens for non-online/non-website payments:
Google Pay does not send merchants their customers' actual card numbers when they pay in stores; instead, Google Pay facilitates a process called tokenization in which a token stands in for a customer’s actual credit and debit card numbers.
As far as I know Google Pay stores a limited number of prepared tokens in the app so that you can pay without the necessity of data transmission by the phone if you want to pay something. But if these prepared tokens are used-up you need an online-connection for making the next payment.
- Customer tokenizes card: A customer adds their card to Google Pay. Then, their mobile device stores a payment token that is encrypted using a limited / single-use key.
- Merchant receives token: When the customer taps their device on an NFC-enabled terminal at the store’s point-of-sale, the device sends the token, token expiry date, and cryptogram to the terminal via the NFC protocol.