I think it's an auto dialling machine testing for numbers that actually answer. I won't ever answer an unknown number because I've had bad experiences doing that.

Calls and no message .
Annoying.

This number keeps calling me and doesn’t leave a message.
Some scammy rubbish. Will block number

Calls my phone every week. Never a message. Spam or scammer.

8 calls from this number with no message left

Caller: 0413 675 845

Didn’t answer - when I opened the missed call message noticed it was the same number that tried to call on the 20th December. No voicemail left. Either a bot/scam or can’t be too important 😬

Caller: 0413 675 845

I think this caller is goading me to call them back because when they call they hang up after only 3 rings or less. I'll block them if it continues.

Very annoying call with no message left. Most likely a bot. Never answered yet they continue to call.

This number called twice but each time no one spoke.