Caller: Unknown

So I get a call this morning from a mobile number. 0424 149 304. I answer it with a cautious hello as it wasn’t a number I recognised. A male voice sounding a bit like a rehearsed recording. States that my tax file number has been suspended and a warrant for my arrest has been issued. Then hangs up. Of course I quickly put it on speakerphone so my son could hear it all. I’ve been getting some strange text messages over the last few weeks from a variety of different mobile numbers. I’ve blocked them all but somehow keep getting them.