Got a call from 040020664 too but didn't answer as not one of my contacts. Googled number and found this page.

It sucks that I do not answer my phone unless I recognize my partner's number calling me any more. I let the phone ring until the scammer does not leave a message instead. Then come here & read that I was correct, so then I block the number & in a little while the same scamming calling centre just rolls over to calling me from a different phone number. These scammers and thieves are basically holding our communications systems hostage.

Called and when I answered hung up straight away. When I tried to call back the number said it was disconnected.

Bad connection -- obviously a scam -- Indian or Pakistani accent... When it finally connected in English (I heard some lady say something in another language first) the guy said he was calling about NBN -- I stopped him there and told him he was lying and he should find another job - not call me ever again. The number is now blocked. You can block it on your phone too.