Sam! I got my first call on August 28th too! Then 2 more on the 31st and one again this morning. Never answered as i didn't recognise the number, BUT we did change our Foxtel box... strange!

Get a call from this number and also 8664 3800 presume they are connected - no message.  No ability to phone, telling me all lines to the area are busy - try again later.

I got a call today and answered it, but nobody was there and it hung up after five seconds.I have a silent unlisted mobile number, so it's either someone calling a block of numbers or possibly someone linked to real estate rentals/credit checks - the last couple of weeks I've been inspecting and applying for new rental properties.

I have just signed up with Optus - a brand new number which is only 3 days old and I am getting calls from this number also. Rules out Telstra unless they somehow have access to Optus's new mobile connections?

Yes, it it Telstra.  A Telstra call centre.  I have been advised that they use an autodialer, which calls about 8 numbers at a time, even though they only have a few operators.  They do this on the pretense that half the numbers will not answer, ring out, be engaged etc...

Telstra was recently fined over $100,000 for calling numbers that are listed on the Do Not Call Register.  Hopefully they'll get the hint.

Of course they have access to Optus' data.  Optus rent almost all their infrastructure and network access from Telstra.