I called back number 0409 449 190 rang once then goes to busy tone.

Missed a call from this number. No message left so I suspect spammer. Blocked.

Caller: 0409 449 190

This number operates, via getting you to call back - an international number - 61 - and then an answering machine with music, puts you on HOLD - the whole point being that as you may wait, it is making money ! DO NOT CALL BACK / ANSWER.
I have reported this number - has a very high 85% security risk !

Caller: Energy Saver re power bills

Auto dialler so delay before call centre picks up. She sounded South East Asian. Pointed out this numbers on the do not call list. She hung up.

Yet another number to block.

Hung up once I answered. Not sure who these people are but number not familiar.

Dodgy. Missed a call and rang back
But Optus says it’s disconnected.

Caller: Electric company

Definitely scam. Said something you need to change some plan due to their new policy when I asked for more details and send it by email, they hung up right away.

Caller: Energy Compare

Called the home phone in the middle of the night at 00:38 and woke the house up. NOT HAPPY - son has English Exam next day. They rang my mobile the next day and I questioned the fact that they can only ring during certain hours - indian guy agreed and then I let him have it for waking up the household during the night.
As if I am going to buy anything from a cold caller anyway!

phone called picked it up ... it was silent on the other end.
called back and it says the number your calling is disconnected.

SPAMMER

Called back immediately and it said disconnected.