That is amazing. I found this thread also: Voip Settings for VDSL - TPG Community
Imagine having to work for a company like TPG an being required to peddle such nonsense to customers!!
From the link:
I understand that you wish to avoid any downtime. Your request to have the sip settings for TPG Home Phone so you can configure it on a 3rd party equipment is currently not possible as our system is not designed that way.
What rubbish. You might find this link from ‘Whingepool’ interesting 
https://forums.whirlpool.net.au/archive/2531183
Looks like the details can be extracted and it will work - interesting discussion - in it, a TPG spokesclown says:
We strive to do our best to assist customers with their concern. It does not mean we will provide you what you want in this case. Our decision not to release the VoIP settings is non-negotiable.
[…]
I believe other major ISPs will also not release these settings for security reasons.
Wow. Just wow. “security reasons” - wasn’t that the excuse in the “Anthony Blunt case” ? They’ve even changed their terms and hobbled their routers in response to people trying to get the config and use other products. I wonder on what golf course that agreement was made with the ahem-ACCC-ahem 
…
No TPG for me.
Edited to add: Hidden SIP Settings on VR16000V - TPG Community
For security reasons, the home phone component of your TPG NBN Fibre to the Node (FTTN) bundle is encrypted and it requires the use of our modem for the VOIP service to work.
Unfortunately, our modem does not support 3rd party VOIP services, as it is designed to be used for TPG VOIP services only.
… laughable …
