Call supposedly from Telstra Internet Security. Have seen unusual online activity on my internet line. I use WiFi. Was told that John Wilson could call me & Max Weber was the senior technician. I asked for a Telstra employment number & was given TEL plus about 10 numbers. Did not believe him (an Asian voice), so said I would have to call back as I was in the middle of something. He advised that if I was on the internet, he could demonstrate what was going on (more suspicion arose). I was given another number to call back - (08) 8121 7991 but the address was in Melbourne.

Spam.. blocked and delete

I declined the call and they never left a message

Number called me. I didn't knwo the number so didn't answer. No message left. Blocked & deleted call history.

Caller: John from NBN - so he said

Informed me that my internet would be out of service for two days! When I responded with What? Hung up. Definitely a number to block.

Yeah, exactly the same here. Wanted me to type something into my browser so he could show me what's going on. I hung up.

They hung up straight away, probably dodgy

Broken English accent, telling me to get of my phone & look at my text message.
Very strange.