Hi how do I configure my Asus RT-AC66U for VOIP? I am using Maxis Home Fibre.

I noticed whenever I select 'Maxis-Fiber' in my router it sets my LAN3 to VOIP. How do I utilize that? Right now my VOIP phone is still connected to the Thompson and I really like to totally remove it. I want my setup to be as simple as possible.