Hi @truonghue . If you use the TPG VOIP home phone, you have to use a router from them. If the HG659 has some problem or is slow, you can buy a TPG router, probably a TP-Link Archer VX220 from TPG.
If you don't use the VOIP phone, you can buy some other brand/model.
There are "Asus DSL" models with RJ11 connection. You must be on FTTB or FTTN connection.
It looks like the Grandstream device is just a telephone adapter. It still has to connect to a router. If you use it, you need to buy a phone service from some 3rd party provider. You can't use TPG VOIP service.
