Called my daughters phone 6 times in the last week without leaving a message.
I answered today - they say they are from ACMA regarding our mobile phone service. When I advised they were calling a minor & asked how they got her number they didn't really respond. I asked for her to be taken off their calling register - which he said he would

they keep calling and dont leave msg

They keep calling and I am not answering. They do not leave a message

They ring and no one says anything and hang up.

Keep ringing me. I've just blocked their number

Mobile phone plan apparently. I couldn't really understand the accent.

They called at 5.15 when I was already on a call.left a msg saying "hello? Hello?" Then hung up

They phoned, i answered and then hung up.

Hang up call and left no message