Obviously this is about the power outage in Spain.
While normally, if a card declines, people would probably have to leave their IDs with the restaurant while they went to get a withdrawl from their bank; this is a power outage, withdrawls wouldn’t work. It would be silly to arrest people because of a power outage. So I’m assuming people just have to give the restaurant owner/management their identity info with a promise to pay?
And power outages shouldn’t affect buses, since they run on gasoline/diesel, but the payment system processing transit passes might not work. Do buses still get run during a power outage and they just let people on for free, or do they just shut down the bus lines?
The remarkable thing is that modern chip-and-pin cards do support that sort of “offline” transaction, although fortunately without the carbon copy paper. Specifically, a non-networked credit card terminal can present a transaction to the chip, the chip will cryptographically sign this transaction in a unique way, and the terminal will store it for later submittal to the credit card company, when an online connection is possible.
For a typical “online” transaction when there are no connectivity issues, the third step would send the transaction immediately to the credit card company, so they can have the option of declining the charge. The cryptography is otherwise the same, and it’s why offline transactions are possible.
Some vendors, I think, like SNCF (the national rail operator) in France use offline transactions for their ticket vending machines at rural stations, where there’s no guarantee of being within mobile phone service. The card issuer also usually programs some safeguards to prevent abuse, such as X number of offline and then an online transaction is mandatory, or a limit on the value of purchases (eg $50 max for offline). After all, there cannot be a check against one’s credit limit when offline.
In the USA, it is exceedingly rare for credit cards to be issued as chip-and-pin (but it can be found), and while offline transactions can be performed with chip-and-signature cards, it’s rarely enabled since most/all terminals in the USA have been online since the introduction of electronic credit card processing.
Contactless chip cards might have changed the calculus though, since there is no PIN at all for these transactions. So perhaps issuers might allow a few offline transactions when contactless.
The odds of the power being out are more likely than a lack of network connection in the US, we tend to have generators or other power backups for cell towers and landlines even when the power goes out.
In the US, telephone land lines actually carry their own DC electrical charge which is provided by the telephone central office and travels through copper wires to each phone.
This is why, during a power outage in the US, a land line phone will typically continue to work. The exception being if the outage is large enough to also take out the central phone office.
The central phone office frequently has its own backup generators or independent power supplies which is what I was referring to.
Gotcha. That makes sense why the phones always seemed to work in every power outage. I wanted to mention the 48 volts DC setup because I’m not sure if that’s common or standard outside of the US.
Oh yeah, your comment was a great addition!