Another call centre spammer

Left me a message, " hello, hello", a if it was someone I knew. Creepy. But in the background the usual call centre bustle. After watching the ABC TV documentary the other night I know how utterly ruthless these people are.
A lot of comments here say they called the number back. Don't do that, please google why.
If this caller did know me they would have left a detailed message. But they seem to have cottoned onto the theory that only people you know leave a message. That's why it's creepy.
It's infuriating that we get interrupted by scammers, which are basically cyber criminals.