It is Do Not Call:
https://www.donotcall.gov.au/
Yes, and it "Does Not Work" :-)

Or, more precisely, it works for legitimate businesses. The guys from India trying to sell you crap and the scammers after your credit card number don't care what list you're on.

Get an answering machine, and then dial a non-working number. Record the "beep-boop-beep" tones at the start of the intercept message. Put this tone at the start of your answering machine message. Their autodiallers may be programmed to detect this sequence of tones and automatically remove you (presumed to be non-working) number from their database.

I've tried the above, and it does seem to result in a reduction of junk calls. Don't know if you have the same system in Oz, but worth a try if you do...