Dual WAN with BSNL FTTH and VoIP

[networkwhisperer]

So I was hoping someone here could help or provide advice on something I'm looking to do:
I recently got BSNL FTTH as a back up broadband connection. It came bundled with a new BSNL number, delivered over VoIP.

I have an Asus ac87u set up to do dual WAN with failover between my primary broadband provider and BSNL FTTH as secondary. The primary connection comes in as PPPoE on an incoming ethernet cable, and goes directly into the ac87u's WAN port. The secondary (BSNL FTTH) is an incoming optical cable, terminated by a BSNL provided Optilink ONT cum router. The Optilink router plugs into the ASUS ac87u on one of the ASUS' LAN ports. I use 192.168.2.XXX as the subnet for all my devices; the ASUS is the gateway for this. I've put the Optilink on 192.168.1.XXX and it serves as the gateway for the secondary connection.

There is VoIP set up in the Optilink and an RJ-11 jacked cable that come out of the Optilink and into a POTS instrument for calls on the number that came with the FTTH.
From what I can make out, the Optilink VoIP end point is given a static IP on a 10.XXX.YYY.ZZZ private network, with the SIP server it's supposed to talk to also on the same 10.XXX.YYY.ZZZ private network

All of this works right now; I can make and received calls on the new number and the broadband fails over to the secondary when the primary fails.

What I'd like to do:
1. I'd like to avoid the additional hop (ASUS --> Optilink --> Internet) for the failover case, and get rid of the 192.168.1.XXX subnet entirely.
I'm assuming this would involve putting the Optilink into bridge mode and having the ASUS do the PPPoE etc.

2. I'd like to be able to use the VoIP number with VoIP apps on smartphones or IP phones on the 192.168.2.XXX subnet, and do the fancy things that SIP/VoIP allows.
In particular receive incoming calls on the VoIP number on any chosen device, and call out from any device etc.

So on to the questions:

0. It is possible to do both (1)and (2) together, correct? (Obviously I'm assuming it is)
1. A route between 192.168.2.XXX and 10.XXX.YYY.ZZZ will need to be added, correct? Is this all that's needed for a VoIP client on 192.168.2.XXX to reach the BSNL SIP server and make/receive calls ? (Assuming route is necessary but not sufficient...)
2. Will I need to run my own SIP server or something? (Does/can the Optilink act as a SIP Server or proxy by the way? I can see a Dialplan as an advanced configurable option in the Optilink's configuration interface)

What's primarily causing confusion for me right now is how to set up for the effectively two outgoing networks for the BSNL (the internet one and the VoIP one) in bridge mode, while not messing up the dual WAN etc...

Any tips/advice/pointers appreciated !

 

[Dark_Nate]

You have two different ONTs, right? From two different ISPs?
So put both in bride mode, in BSNL ONT, bind the bridge interface to the Gigabit LAN port of the ONT if there is one, same for other ISP's ONT.
Then connect both ONTs to your router as you already are doing. Then use the router to establish PPPoE connection for both WANs. This will eliminate the Double NAT problem.

For SIP/VoIP on BSNL, it's MAC bound. Which means it will only work on the BSNL ONT.

Some ONTs give you the option to bind bridge interface with VoIP service, which is a little confusing really. But I think you only need to bind to one LAN port on the ONT which you will use to connect to the router.

 

[networkwhisperer]

Just the one ONT; the primary ISP connection already comes in over a cat5 cable so the termination and PPPoE is essentially done by the Asus, without an additional ONT/modem needed.

If I bridge the ONT and set up PPPoE for it on the ASUS using another LAN port, what happens to the voice side? Or will the same interface work for both voice and non-voice traffic (tagged as different VLANs) ?

(and thanks for the reply !)

 

[Dark_Nate]

Voice will work via ONT. Voice is independent of PPPoE. When you enable bridge mode, remember to bind bridge interface to LAN1 port of ONT.
Also, Voice has separate VLAN ID from BSNL anyway.

 

[networkwhisperer]

And noob question: Does the voice port on the ONT (that takes an RJ11 jack) count as an interface the same as the LAN ports? Or is that treated somehow differently (and if so what happens to it with the ONT in bridge mode) ?

 

[Dark_Nate]

That's the confusing part. Test it out.

First, enable bridge mode anyway. Then bind bridge interface to LAN port. Then establish PPPoE via the router. If it's working then see if VoIP is also still working with the same configuration given by BSNL.

If not bind bridge to both LAN and the VoIP.

 

[networkwhisperer]

Got it. How does one typically reach the admin interface of the ONT once it's in bridge mode? It won't have an IP then so I'm assuming the usual way won't work...?

 

[Dark_Nate]

You'll need to use the LAN port 2 to access the dashboard. Since LAN1 is binded to the bridge interface. IP Address stays the same unless you changed it.

 

[networkwhisperer]

So I looked at the ONT's admin interface to do as suggested and:
1. There are two WAN configurations, one for "internet" and one for "voice"
2. The setup for "voice" doesn't let you choose a LAN port to bind to; that seems to be available only if you've selected the type to be "voice"
In other words there seems no explicit way to bind both VoIP and LAN to the bridge.

The other config parameters like IP address, gateway etc are available for the "voice" WAN setup. The only difference seems to be that the IP is
a static one (on a 10.XXX.YYY.ZZZ private network) and not handed out from PPPoE. So here's another question:
Given that the ONT has two LAN ports, if I were to set up a third WAN config, with config as for the "voice" one, except that I choose the type as "internet" and bind it to the second LAN port, and say plug in an ATA to that LAN port and the telephone to the ATA, is that in principle equivalent to connecting the telephone to the ONT directly ? (I don't have an ATA at the moment so can't test that directly...)

 

[Dark_Nate]

Then don't bind voice with LAN. Problem solved. Ask BSNL for voice WAN setup information.

Dude, voice-over FTTH is MAC bound, why do you even want to use it? I never set it up on my ONT.

We have WhatsApp, Discord etc for VoIP.

FTTH Voice calling does not have any privacy, it does not have end to end encryption, anybody can listen in.