I've had quite a few calls from (02) 8524 5912, which all ring off before I get to them. not surprised to find it's a call centre asking for money.

Got another call from this number on caller ID and when I returned the call the number said it was disconnected
(02) 8524 5912
Does anyone know what sort of scam this is?

I get the same. Since we're both getting calls from the same number it's likely that it is either a scam or a telemarketing thing. The long silence is a good indication that it's a machine making the calls or that the call has been routing from offshore. I don't wait long enough to tell who it is anymore. I got a very pesky salesperson once who just don't get the hint.

Got a call from this number and answered in time but no one there. Have gotten several from this
(02) 8524 5912

I let the call go to my answering machine and could hear an office/call centre in the background.

We are so tired of these calls ( 8 today but it is every day. From this number and 82112222 and also 82112200)  that we have diverted the land line to the mobile so we can see who is calling. We then save the numbers as telemarketing or do not answer in contacts so we can see who is calling and know not to bother answering.

Another call while typing this message from 82069888 with a delay then a recorded message saying goodbye.

Will be having the Telstra land line disconnected.

I have been getting calls from this number (02) 8524 5912) for a long time - months? - and the latest was this afternoon at 12.15pm.  Rang it back out of curiosity and received a recorded message which said "we have been trying to contact you re fundraising".  Speaker had an Australian accent as well.  Obviously some kind of scam, I think.