Welcome to the TPG Community!
I can see that a call back has been organised from our Technical Team to assist you with the homephone concern. They have tried contacting you today but was unreachable. You may reply to the SMS sent for your most convenient time to receive a call or you may also let us know here.
Regarding your query, there isn't any particular specification for the handset that you need to use. All you need to ensure is that the phone cable is connected directly to the UNIV-1 port on the NBN box. It will only light up whenever in use and yes, your homephone is active and should be working.