The voicemail left by this number is a prerecorded message with a female Asian voice, sounding like Chinese. Personally I think it best to never call back these pest callers and I think it's playing right into their hands (surely it's like unsubscribing to spam emails: by unsubscribing, you are confirming that your email address is in use and thus you could end up getting more spam, not less).

I would guess that this is an overseas call centre that ports routinely through a local mobile number in Australia in order to appear as if the spammers are supposedly calling from Australia instead of from whatever country they are calling from. I've encountered that before with Optus (at the time, both their mobile internet Technical Support and Customer Service phone numbers were actually Philippines-based call centres and were porting through local numbers in Australia to pretend like they were supposedly calling from Australia instead of from the Philippines).

Where is the truth in this world? So many "Masters of the Bullcr*p" out there! Deny them the audience that they crave and do not engage with them at all! Treat them with the respect that they deserve..NONE. Treat them with the contempt and disdain that they deserve..UNLIMITED.