Scam/Phish bait - autodialler gives a message in (what sounds like) Mandarin and then repeats in English (with a very North American sounding accent) along the lines of "This is an urgent notification from Optus. We have detected unusual operation with your phone number. Your phone number will be deactivated within the day". Message ends there. My number is NOT with Optus

You're obviously meant to call back. So I waited 18 hours, turned off Caller ID and did (a few times)!! Just an engaged tone, so possibly the scam had packed up/moved on by then, they only answer if they can see your number or maybe it's tied up all day doing bouts of dial-outs. Who knows? Who cares?

Call came in at about 5:11pm Sydney time (DST in effect), 28/03/2024