I called back number (03) 9021 6946 rang once then goes to busy tone.

Caller: ?

I answered, silence then hung up. I assume the robo callers were all busy.

scam today

I've said this was a scam call because it was scammer behaviour. They call, butting heedlessly into your life, then hang up as soon as the answering machine kicks in.

My phone log shows 3 missed calls from this number in approx 2 hrs.
Unknown number so I wouldn't have answered anyway! No message left so assume scam!

Called 3 times, we did not answer. Hung up after 4 rings when it went to answering machine. Blocked
It would be one of the following, based on our "unknown caller" history:
Scammer (85%)
Illegal cold caller (5%)
Charity seeking donations (5%)
Govt survey (5%)