They said they were from Telstra and called me as it was noticed by them that my IP address had gone from private to public and explained it was dangerous. I asked how would he know as I'm not with Telstra and he called my work mobile and we operate through a secure VPN. He then tried to explain how Telstra owns all the network and are responsible for ensuring security and solving issues. I hung up he called back. He didn't leave a message.
Bad phone connection , you'd think Telstra could get a good phone line.

Answered the phone. Np response hung up after a few seconds.