I called back number (03) 9039 2642 reached voice mail but did not say from what company.

I had the same thing happen to me I haven't called back yet and don't intend to

I called the number and no one answered. Got an electronic voice saying the person I called doesn't have a valid voicemail. It's a bit suspicious.

Received a call from this number (03) 9039 2642, when answered, they immediately hung up, I tried calling back a few times, each with various lengths of time before they hang up during the ring.