Yes, I've used Square for about 5-6 years.  I've had many people tell me their credit card wouldn't work on the Square app.

100% of the time, they were wrong.   They were either typing in the number wrong, not putting in the CVC, and if they're not, their bank is blocking the transaction. (Probably because of the drastic differences in states) They're trying to protect him from fraud.  If he calls the number on the back of the card, they'll whitelist the transaction.

If your card works, it works on Square.



On a side note, this is also a known ploy for scammers. (Not saying this guy is trying to scam you) They'll say their card doesn't work with so and so.  Then they'll recommend a credit card service they could use.

Fortunately, they'll typically choose one that you've never heard of from Europe, etc. and it'll immediately send up your red flags.