Can't remember which one but credit cards were offline for a time with something and places that still had the carbon paper roller things stashed away took them out and used them. They should keep those things around.
Shop I worked for in 2005… I think … ran cards when the connection was down and took card impressions, and I think the transactions were all auto submitted when the connection came back up.
national chain. I think it stored the transactions for transmission, and in-case it didn't go through we also had the imprints as proof of having the card at the time of transaction. I assume it processed them as a different option instead of instant approval, and probably has different liability implications if the transaction is later denied. Being a big company, was probably fine.
Not sure how much good that'll be... A lot of banks are giving out cards where the numbers are only printed, I haven't had one with raised numbers in years.