Pretended to be from Telstra. When I queried why the call was showing as coming from New Zealand (+64 22 795 4572), the lady made an excuse. She told me my IP address had been switched from private to public, then wanted to 'show' me how exposed my computer was. That then led to the usual checklist of running NETSTAT etc commands and misinterpreting the results to 'prove' baddies were connected to me. When I asked for a public number to call her back on, she became very rude and hung up.