Possible spam. I missed the call from this number and when I rang straight back, it said that the number has been disconnected.

Caller: Guide dogs australia

I guess various NFPs using mobile numbers to raise some more funds. Whilst I get it, it’s terribly annoying

Caller: I dont know

Missed call - no message left. Called back and received a message bank for Clever Contacts - advised they were calling for a charity but didn't specify which one.

I think it's linked to National Breast Cancer Foundation (or third party call centre acting on behalf) donations - calling to sign people back up, etc.