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Message 1 of 7

Fibre 900 / Digital Voice / Ubiquiti - my solution…

Had Fibre 900 installed yesterday and was moved to DV at the same time. Main goal was to move back to my Ubiquiti network ASAP - this has been flawless for the last 2 years on FTTC.

Engineer setup Smart Hub 2 and ONT and tested all OK with wired and wireless device.

DV didn’t work straight away but he said it would be moved across later in the day which it was.

Background: The only reason we have a landline is because the wife and the mother in law spend hours each day gassing. Nobody else ever calls the landline and I always use my mobile to make/receive calls.

It has taken a couple of weeks in the lead up to install day to explain why the phone calls will now go over the internet, that it won’t work in the event of a power cut etc etc, but I am still working with ‘but my mum remembers our landline number’.

I only discovered the advice to order new FTTP, then migrate landline number to VoiP which would then cease FTTC after I’d placed the order and was approaching install day so our ‘precious’ landline number has been moved to BT DV and I’m now in a 24 month contract.

I really didn’t want the double NAT issues of running the ONT>SH2>UDMPro.

So my initial solution has been this…

1. As soon as DV went live yesterday I used Call Diversion on the DECT handset to forward everything to my wife’s mobile number.

2. Unplugged the SH2 and plugged my CAT6 patch lead from the UDMPro - aaahh Unifi network back up and running. 😍


1. Call Diversion is not free for the forwarded call as the wife is on Tesco mobile. So I am paying monthly for the unlimited call package on top of the cost of the Fibre 900. 

2. She has already complained that she can’t wedge the Samsung mobile phone into her neck like the BT DECT handset did.🤔

3. The mother in law is happy because she still just dials the landline number and nothing has changed for her. 🙄

4. Outgoing calls need to be made from her mobile rather than the landline which seems hard to comprehend. 🙄


1. Assume Call Diversion is permanent once set and doesn’t rely on the SH2 being live?

2. Am I going to be forced to ‘provide’ a DECT handset on landline and suffer double NAT rather than this solution? place your bets 🤣


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Message 2 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

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Message 3 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

I don't have much advice but I do know that if you give the secondary router a static IP address, and then put it in the DMZ (Found in the advanced section of the firewall settings) of your Smart Hub 2, then it should bypass a lot of the problems you would have with double natting.

It would still be double natting, but DMZ greatly reduces its effects.

The best solution would be if the SH2 had a bridge mode so you could completely bypass it, but sadly it doesn't. So DMZ is the next best thing.

Or if AP mode is available on the secondary router you could just enable that, and turn off the WiFi of your SH2.

With regards to the call diversion, I think I read on here about someone who had all his calls forwarded to his mobile. So he could then ditch the SH2 and put his own router directly on the line. I think that call diversion became permanent for him? But I'm not sure. I think it can be found in your landline settings of the myBT page... but I could be very wrong as I've never used it. Someone else will have a better idea of it for sure and then probably bop me on the head for being wrong 🤪

Edit: Found a link about call diversion, it seems that it can be permanent:

Message 4 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

Having a bridge mode on the Smart Hub wouldn't help. The IP layer would be passed through transparently hence no access to VoIP in any case.

Message 5 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

Ahh ok, I'm still learning about these things having just done something similar to the above, so I could use a TP Link Wi-Fi 6 router but also keep DV!

Everything is working good surprisingly, since I'd never done anything like it before. I messed up settings on the TP-link and had to reset it to factory default to start all over again, but I got there on my 3rd try lol.

Message 6 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

The best way to learn. Trial and error and understand the mistakes.

Message 7 of 7

Re: Fibre 900 / Digital Voice / Ubiquiti - my solution…

Yep! I even got IPV6 working by experimenting. I just put it on bridge mode in the IPV6 settings page of the TP-Link and from then on all my devices had full IPV6 access... TP-Link even substituted the plain IPV4 for IPV6 Goolgle DNS servers itself somehow, so now it's full 10/10 for the IPV6 test site!