keep getting calls from this number over the past two weeks. when I answer....there is nobody on the other end. when it hits my voicemail......SOMETIMES it will leave a response (but no voice details., just one second of sound file) MOST TIMES I get no message. When I call the number - it sometimes responds with 'not connected', other times nothing

I keep getting calls every 2 minutes or so for the past 2 days. What is this? No one on the other line either. And I haven't entered my phone number anywhere on the internet recently.

I posted earlier. I should add my new phone provider is Aldi, and my old provider (whom I left 2 months ago, shortly before this started happening) was Optus. I also inputted my mobile number into a (seemingly reputable) company's web form as a contact point for sending SMS on behalf of my company - any commonality with others getting called from here would be interesting to know...

I receive frequent calls from two Sydney numbers – (02) 9598 3000 and (02) 9598 3200. Sometimes I get 15-20 prank calls a day, most commonly in ‘bursts’ of 3 or 4.

I cannot find details for these numbers on the net, and when I try to return the call (from any phone at random times) – the response may be a fax, a phone that rings out, or a message saying ‘number not connected’. These calls sometimes leave ‘brief’ voicemail messages – either a fax, or a silent line followed by the disconnect. This is not determined by either of the originating numbers (above). If I were to return the call from my phone with CLI showing, it is a safe bet I will get another burst of 3 calls in return (which is why I no longer make these calls!). i am Yet to test with my CLI hidden (my understanding is that it could not determine my number, hence not call me back, but who knows?)