These people are scammers. They left a nasty message on my in laws answering machine saying they were from the ATO and they would take them to court if they didn't ring back within 8 hours.
I rang the number the next day and asked them what it was about, they still pretended to be from the ATO and said they were going to get a warrant and go to court about an ATO matter. Think they were after either personal details or money. They were very aggressive and also had a foreign accent.
I told them that I am a tax accountant and I know how the tax office works., and their number is nothing like the ATO's. He said they knew where we were and they were taking us to court. I then asked to speak to his supervisor and he hung up on me.
I then rang them back, got a different guy, and told him what I thought of them for trying to scam people. More threats from him also, I said I was reporting him to the federal police and asked him if he was even in Australia, he then disconnected the call.