So obviously there are many, many threads with people talking about TPG hiding away their VOIP/SIP settings insider the supplied router's firmware, never to see the light of day for reasons no one can comprehend. I've just joined the NBN (finally) on FTTC through TPG. I need VOIP for my home security system to dial-out, but I also run an expensive Sophos hardware firewall appliance as my router that I sure as heck don't want to get rid of. So I started getting concerned when reading that I would not be able to use the included VOIP service if I wasn't willing to use the supplied TP-Link router.Sure, there are threads talking about hacking the firmware, running double-NAT daisy chained routers etc. I didn't really like the sound of any of those. But a post by @marius here (https://community.tpg.com.au/t5/Home-Phone-Voice/Voip-Settings-for-VDSL/td-p/19566/page/3) made me think, is this configuration possible?
Well, at least in the case of TPG, yes it is. The scenario essentially runs two routers in parallel with the modem. Now with FTTC, NBN supplies you with the NCD which is just a VDSL2 modem in bridge mode (this solution could also work with FTTN, but you would need to run a standalone VDSL2 modem). From the modem's gateway port, you run an ethernet cable into any old network switch you might have lying around (I had a 5-port gigabit switch handy). From the switch you run an ethernet cable into the WAN port of each router, i.e. your preferred choice of router (in my case the Sophos) and the TPG supplied router. Now just make sure both routers are configured for PPPoE, the correct VLAN tag and authentication details.
Well you may think, how could this work? You only get one public IP address and it can't be shared across two router WAN ports. Well, at least in TPG's case, they are in fact happy to assign a public IP address to each router. So essentially you are running two internet connections. On the RSP supplied router, you turn off wifi, plug your phone in, and you've got your VOIP service running. You don't use this router for anything else. And then of course you have your preferred router just doing its thing, with the rest of your internal network connected to it just as you had before.
The pros of this scenario as I see it:
Use any router of your choice to run your internal network
No double-NAT complications
No hacking of firmware
No additional VOIP gateway hardware required
Maybe if you are a heavy VOIP user, QoS might become an issue? Essentially you are relying on the switch to divide the bandwidth of your connection between the two routers. If you happened to have a decent managed switch you could probably handle the QoS in there, but for me it's just not a concern
You have to run two routers, so slightly more power usage (who cares?)
I would be interested to hear people's thoughts on this, and also whether other RSP's provide more than one public IP per account?
Thank you for your note. I have been trying to do that with my DLINK Taipan modem/router using it as a Residential Gateway. I am confused about the IP settings that I should be using, any suggestions?