Answered call and it immediately disconnected. Rang the number straight back to be informed “Optus advises that the number you have dialed is no longer connected”

Caller: ‭0413 930 363‬

Called I said hello and then they hung up. Called back and it says “the number you have dialed has been disconnected”

Caller: Call center

First time some guy just kept saying hello and then hang up, called back and got the "number is no longer connected" message. About 20 minutes later the number called again and it's just some guy from a call center. Just block it.

Caller: Unknown

Missed call from the number. When I returned the call “Optus advises that the number you have called has been disconnected “

A brief delay (no sound at all) before the caller connected. A lot of back ground noise, sounded like an overseas call center - I hung before anyone spoke. The delay in connection made me suspicious that it was a call center or similar.

I rang once and got disconnected