Answered by accident as I was in the middle of tapping my phone in the exact spot the answer button came up. It was an automated message saying it was NAB calling to authorise a transaction on my debit card that was just made, with options to press 1 or 2 to authorise or decline. I didn't press any, I am not a NAB customer at present. I have been in the past and have had them legitimately contact me for suspected fraudulent transactions, they send you a text asking them to call, the text has no number or link to their site, it just asks you to call their fraud team.