[segmondy]

No they don't. If I sell a diamond ring for $20k and Visa passes that the card is valid but it's not. The buyer just got a free $20k ring. Card could be expired, cancelled, or not have enough balance. The merchant must be paid, their processor has to pay them, the bank that issued the card must provide that credit until the card holder pays it back. If the card was expired or a card with a $10 balance. The card holder will refuse, it get's really mess fast. Visa is not willing to assume such risk, they simply provide a network. If it goes down, it goes down and everyone on their network is screwed.

When dispute is at play, it's a hot potato that no one wants to hold between the merchant, processor, ISO, sales agent & bank. The card networks have been smart to eliminate themselves from that step.

[Terretta]

> No they don’t.

On the contrary, I developed early merchant and payment gateway tech, and they absolutely do. The scenario you describe is extraordinarily rare, which allows an arbitrage between CAP perfection and customer satisfaction.

On a separate note, at any given time, some parts of our national payments ecosystem are “down”. There are enough players involved you have an appearance of resilience.

You can see this in a mall, when one store’s card swipe terminals are down, and another’s are not, and almost never happens that all the stores are down at the same time.

You can think of all these other players as an incidental circuit breaker pattern upstream of Visa.

VisaNet itself is surprisingly unscaled, capable of only about 24,000 transactions per second. Twenty years ago, our gateway would hit 15,000 transactions per second real world use. To do that, we scattered/gathered across many independent paths into card networks and various merchant banks.

https://usa.visa.com/content/dam/VCOM/download/corporate/med...

https://www.capgemini.com/wp-content/uploads/2017/07/Domesti...

[nulbyte]

Actually, merchants, acquirers, and issuers can do this. It happens sometimes. When it happens, other limits come into play downstream, such as terminal configuration. There are separate offline limits, and it is unlikely they would set it that high, so a $20,000 offline charge would be declined, even if a lesser charge would be approved, stored, and processed later. As for expired cards, the expiration date is on the mag stripe and in the chip, so the transaction could be rejected at any point, even offline at the terminal. It's also printed on the card so it might be rejected before it's even swiped or dipped.

[lathiat]

It's even done regularly in some cases, various US airlines take "offline" card transactions and process them later for food & drinks.

There are of course limits on how big an offline transaction you can take intentionally or unintentionally and probably the airline wears the full cost of failed transactions in this case.

Doesn't matter that much when its for a $5 coffee, plus they know who you were if they really wanted to chase it down.

And as mentioned electronic terminals absolutely have automatic offline modes also.

[jeremyjh]

They absolutely do, it is called "stand-in processing". I saw this while working in ATM at a major bank. The terminal operator (e.g. in our case, the ATM authorization system) can stand-in for the payment network when required. There are per-card number transaction limits that are well-defined in their contracts, and fraud liability can shift during this period of time. The payment network can also stand in for the issuer. In either case, once the network is restored all the authorization advices are forwarded.

[seanmcdirmid]

Credit cards are very asynchronous, going back to the days when carbon copy paper was used and no in time verification might have been involved at all.

Shop owners would even get a reward for snipping a bad credit user’s card in half (something that survives to this day only as a meme).