Welcome to the TPG Community!
Apologies if you're not able to use the homephone service. I've managed to locate your account and have ran remote tests on our end and the test result was inconclusive.
Could you please be more specific with what type of issue you are experiencing? Is there no dial tone? Are you not able to make/receive calls?
All you need to ensure is that the phone cable or the base of your cordless phone is connected directly to the UNIV-1 port on the NBN box. It will only light up whenever in use.
Let me know if the step above works.