It seem that by using SMS the answer is yes.
Interesting that with a power blackout banks or ATM's could not work.
Whilst some cash would have been in circulation, the chances of a longer blackout may have ended that as merchants
collected the cash & paid it to suppliers.
But with inflation factored in the long term use of cash may be in dout anyway.
So the winner(?) in a long blackout seems to be crypto or BTC, with more adoption & acceptance.