Silence, then heard some background noise of people talking. This is probably a number that calls you to see what time of day you're likely to answer the phone so that drop-call companies can call you and try and sell you their products/services.

Got a voice recording about my internet service. I'm pretty sure this number and many others are involved in scam to get information. I hanged up after I heard a little of the recording

I called the number back.
Telstra said it was not connected 😡