I called back and it says that number is incomplete or incorrect which is odd because it just called me two minutes ago.

Caller: Don’t know who called me?

When calling back it’s disconnecting going into voicemail can’t contact f*ck this ppl

I picked up and said "Hello this is [my name]" and then just heard them say my name in a low, creepy voice before hanging up.

When called back Optus advises the number is disconnected.

I called back number 0480 368 810 rang once then gets disconnected automatically.