They didn't leave message so I rang them via Skype. An Indian (?) female voice asked me to leave a message and my phone number so I said I wouldn't leave my number and accused her of being a scam artist!
I have had quite a lot of numbers which seem legitimate but I'm beginning to doubt them as they come up with addresses so they aren't call centers.

I returned the call claiming to be nbn it is a prank . called devirted to an elderly lady . Said she has had heaps of people calling . She was calling the police

i was told to press 1 to trans who said they were telstra i questioned that they were telstra and they hung up