There are two options here.
One: Telstra wired your apartment to an ancient RIM cabinet, and you can only get a phone line (no internet). You can prove this by getting the cheapest Telstra phone line connected - this will be no problem (although most alternative phone companies, e.g. Optus, will turn you down flat once they discover the RIM cabinet). Trying to get any non-phone-line internet will instantly fail, but getting the line and then trying to order internet afterwards (from anyone) has a chance of working - a request will go in to Telstra to move you around in the cabinet to see if they can find a port which can provide internet. I got stuck in this hell for 7 months - until one day someone cancelled their service, and I got to steal their port. There is no queue - you just have to keep applying and one day you get lucky. You'll then be stuck with probably ADSL1 speeds, and in the "off net" pricing section of each ISP, but at least you have internet.
Two: The apartment block as a whole has one connection, and then resells that connection to each apartment. This isn't unknown for recent new developments. Developers aren't required to go with NBN (for large new estates) or Telstra (for small new developments) - these are only connections "of last resort". Developers may contract any company they wish to connect a service. Talk to body corporate and/or other residents in the same block, and see if they can shed any light on it. If this is what has happened, you should be able to get decent, fast service - but expect to be paying serious money for it.
If it's case one, you'll find that RJ45 is wired up as an RJ11 using the middle pins only, and is actually a standard phone line. In case two, it's probably Ethernet, but won't be active until contracted.in the apartment there is no rj6 ports (phone line ports) however there is a small cluster of ports housing an ethernet port (rj45), 2 coaxial cables (1x male, 1x female) and 2x tv antenna ports also male and female respectively.