Obviously a scam call

I rang back & the recorded message was this number is disconnected.

I forgot to mention that this number rang me at 7.55pm in the evening.

I called back number (02) 4974 2716 rang once then gets disconnected automatically.

I did not pick up because I did not know the number. Then I rang it back about one minute later. A recorded message said "Optus advises this number has been disconnected". Very suspicious.