Oh yea

definitely fake. i said hello but not my name, no response for 5seconds then they hung up.
i always withhold my name if i dont know the number so then they can't make out like they meant to call me.

Caller: Energy service

Called wanting to give me comparisons on energy prices in my area. Had my postcode and wanted to know energy provider. Said they got my details from a third party. I hung up when they put me on hold to pass me on to a supervisor.

Missed call, no message, assuming a scam from other comments.

Received a call advising they were from NBN and had observed security incidents on my NBN internet connection over the last couple of days. When advised I did not buy a service from NBN, I suggested they contact my service provider and if they could send an email confirming the type of alarms/incidents observed, allowing me to review.

They asked for my email address, I refused and asked what email address they had on file, they read out an old email address. I suggested the call was suspicious and was advised if I put the phone down, they would disconnect my internet service.

Scam. Called mobile re NBN problem, not asking who i am, nor address, just asking on white box which light is flashing, then another guy ask me to go to W3C Markup Validation Service, asking how many errors ... I said this is not my mobile, he hung me up...

Answered the call but no one spoke then they hung up. Sounded like a call center as I could hear people chatting and typing in the back ground