Following BasilDV's mention of ADSL2+, I re-read the original post and I realised that I had responded to the original post assuming the poster was in a situation similar to mine, ie, installing a modem with built-in telephone ports and being told by TPG's installation guide to connect a telephone directly to one of these ports.
To clarify: I am on NBN-HFC with a HG659 modem/WiFi Router/network switch.
After installation by NBN technician was completed, I connected the HG659 modem to the NBN cable modem and configured the HG659 to connect to TPG. After checking that I had internet, I then plugged in a phone in one of the two phone sockets on the HG659, verified that dial tone was present and made calls to verify that calls could be originated and received via the HG659.
When everything was working, I disconnected the phone from the HG659, I then disconnected Telstra telephone wires (coming from the street) from house telephone wiring, plugged in a patch cable into one of the two phone sockets on the HG659 and connected the other end of the patch cable to the house wiring (where I disconnected Telstra wires), making sure I connected the wires properly - red to red, green to green, etc. By doing this the HG659 modem is now in control of the home phone wiring.
With a phone plugged into the Telstra-installed wall socket in the kitchen, I again checked that that calls could be made and received.
