When the number is dialled you get the message, "Optus advises that the number you have dialled has been disconnected".
I've actually kept all of these numbers. When I can get $1400 I'm getting a forensic outfit to chase them down, then I am bringing an action of stalking against them.

My phone is never turned on, except to make a call. So I only ever see 'missed calls'. And as I don't recognize them, I don't call back, except that one, just to see if I was imagining things.
So guys, don't call 'em back!

Rang but did not leave a message

rang and didn't leave any message.

Scam about power bills and options etc. Hung up on me when I said I was too busy to discuss.