I tried to ring back the number (03) 9278 1615 but reached voicemail for Australian Red Cross

Caller: Australian Red Cross Lifeblood

This is a legitimate phone number and organisation. Lifeblood may call existing blood donors from this number to enquire if they are able to donate when there is an urgent need. (For example when your blood matches a particular unwell patient).

Answered the phone said hello and they hung up without saying anything

That is because it is the Red cross who run the Blood Bank, now called Lifeblood.
As a legitimate caller, they should be required to leave a message,if they are calling past blood donors.

Caller: Australian RedCross LifeBlood

RedCross LifeBlood asking for help with donations

Caller: Red Cross Lifeblood

The calls from this number are asking you to give blood or plasma. A very worthy cause. If you can please book in to give blood or plasma.

Charities such as Red Cross LifeBlood are exempt from the do not call register blocks.

If you a blood donor you're likely to get calls regularly to make new appointments from this number if you haven't given in a while.

Yes how dare they try to save lives. They should leave you alone to revel in your magnanimity.

Caller: (03) 9278 1615

No issue with Lifeblood calling me but they should leave a message otherwise I think it’s a telemarketer.

calm down

No response when I answered the call. If this is ARCBS, it is poor form.

Caller: Claimed to be Red Cross ( interstate)

Called an unlisted mobile number and on do not call register
Complete violation of privacy rights
Claimed to be from RedCross
Have blocked
Absolute Disgrace

Caller: Lifeblood

Calling about blood donation

Caller: Red Cross Blood Bank

Correct number for the blood bank. They were following up on a qustion I had. Left a message & he was no robot!

If they don't leave a message after calling me then they're blocked, I don't care who they are. I'm a blood donor & if it's Lifeblood then they need to leave a message or not call at all.

Saw from the comments here that it’s Red Cross lifeblood. I am a donor, so I assume they are calling to remind me to donate. Will save the phone number, but won’t bother calling them back. If they call again, I will answer.

Caller: Australian Red Cross Lifeblood

This is the Australian Red Cross Lifeblood wanting to book me in for another donation appointment.

Caller: Red Cross

They didn't leave a message but later on sent a text

They are from red cross, its a legitimate number asking past-donors to give blood/plasma again.

you are an absolute disgrace for coming on here to make a post about it - flog!

Caller: Red Cross / lifeblood

They should leave a message.
With the amount of scam callers, none of us want to answer an unknown number that doesn't leave a message.