This was a prerecorded message saying my internet and telephone was going to be disconnected. It then said to press 1 to speak to a technician, being confused I pressed 1 and was put through to some indian sounding man that said he was a technician for NBN.
This "technician" proceeded to tell me that my NBN was going to be disconnected because I had too many devices attached to my NBN, apparently 20 pcs were connected. When I said that if that was the case, then I would likely be using up my data limit and Telstra would notify me of that, he then said I may have a corruption somewhere and made it sound like perhaps I might have a virus. He offered some sort of free service, but I said I already had virus protection and he said that virus protection wouldn't be enough as computer viruses had changed alot over the years.
I then said "so are you telling me that there is no virus protection system currently available that would protect from this corruption or viruses" at which point, the line went dead.

I can only assume this was some kind of fraudulent call from someone trying to gain access to my computer. I will be following this up with the NBN and Telsta.

Recorded message saying my NBN was about to be disconnected. I hang up. Called the number back to get a message saying the mobile number I'd called had been disconnected.