the voicemail I reached when I tried to ring back said this number (02) 9161 2950 is from a company called UK Client Services

Caller: UK Client Services

They called me twice. The first time I kept saying hello and hung up. The female voice was obviously not an Australian voice. Although the incoming call showed as Sydney.
The second time I did not answer. They did not leave any message.
I then rang the number back and an automated message said UK Client Services. Our Office is Closed. Goodbye. I don't know anything more.

Caller: Unidentified - Unknown caller

Exactly the same - The caller called twice in succession - I do not answer unrecognized numbers -
such unrecognized numbers are checked against known databases - and if it becomes necessary
the caller will be made contact with at a later time --- Often callers make a call to test whether any
number will answer - thus identifying a 'Live - Active number' - This will lead to spam calls and
messages

Someone from this number (02) 9161 2950called me and said he's from UK Client Services, not sure what that company is

got a call from this number (02) 9161 2950, the company was called UK Client Services

not sure but got a call from this number (02) 9161 2950 and the person said it's from UK Client Services

someone from a company called UK Client Services called me using this number (02) 9161 2950

(02) 9161 2950 called me once, no idea who this was but they said they're UK Client Services

a company named UK client services called me with this number (02) 9161 2950

got a voicemail from UK Client Services with this number (02) 9161 2950

Don’t answer. From UK.