Tax scammers. Computer voice leaving a message on your phone to call a number, saying they have commenced a lawsuit against you.

Caller: Tax Scammer

Answered the call to a robotic recorded message from the "Australian Taxation Office" saying they were investigating me for tax fraud and since they hadn't been able to contact me a lawsuit had been taken out against me.
Out of curiosity and to mess with them I called the number back and it's not connected.