I called back number (02) 8020 3523 reached voice mail for a company called Australian Red Cross.

I think if it is Australian Red Cross they would not hand up as soon as your answer the call. Must be bogus number.
We have been getting a lot of anonymous calls that we don't answer.

They hung up when they get the answering machine.
Bastards! They should be fined heavily for nuisance calls.

Get true caller app on mobile you can block all these callers and they let you know which callis spam or tele marketers

No. (02) 8020 3523 Red Cross Telemarketer. damn nuisance. Don’t know why I am getting these calls or how they got my mobile no. I get at least 2 to 3 calls a week. Today is the latest, got two calls Monday. I answer and end call that’s their charge. It never stops.