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Can Digital Voice work with this wiring?

john-tejada — Sun, 17 Aug 2025 20:02:51 GMT

My mother is in her late 80s, and told me recently that BT have arranged an appointment to switch her over to Digital Voice. Her phone wiring is quite complicated, and I don't know much about BT Digital Voice (as yet), so I am trying to find out whether it will work ok. Obviously, as an elderly person, the phone is important to her. I want to check it all over before someone visits her to do the work.

I have uploaded a copy of the internal wiring below. I did this some years ago, and at the time, I was aiming to get a decent internet connection to my (late) father's office in a distant extension. Previously, it had only been connected by an old BT cable, and that made things difficult. So, instead, I replaced the phone cable with an ethernet cable, and bundled both network and phone over it. So, a little elaborate, but it did the trick.

So, my question is, how can I make this work with BT Digital Voice. Note that I understand BT would install FTTP into the front of the house (i.e. by the Master Socket location), and also, because the house has an odd split level arrangement, I very much doubt that a DECT signal would reach from the new Hub to the office extension at the back.

(I hope you can see the picture ok. I was limited to upload size so had to compress it a fair bit).

Re: Can Digital Voice work with this wiring?

Anonymous — Mon, 18 Aug 2025 08:54:11 GMT

Google "voice re-injection".

Easier if going to FTTP, or just isolate the extension wiring from the master socket if not.

Re: Can Digital Voice work with this wiring?

imjolly — Mon, 18 Aug 2025 09:32:08 GMT

apart from disconnecting the extension wiring from the main openreach input at master you also need to connect the green phone socket on back of HUB into you wiring normally using cable with 431a connectors on either end - one for hub and one to extension socket

Re: Can Digital Voice work with this wiring?

Ali_A — Mon, 18 Aug 2025 10:56:16 GMT

Hi @john-tejada

Digital voice is supplied through a port on the router, rather than the original phone line master socket. so all phone will have to be connected through a single base from the router, as @imjolly mentioned.

Just be aware, the output power supplied through the digital telephone line is significantly lower than copper wires, so it wouldn't be able to power your stand-alone external bell ringer, for example.

Ali

Re: Can Digital Voice work with this wiring?

john-tejada — Sat, 06 Sep 2025 08:36:44 GMT

Thank you @Anonymous @imjolly @Ali_A for your very helpful replies.

I’ve reworked the wiring based on your feedback and some additional Googling. Please see below. How does it look?

A couple of points:

I am assuming that the reinjected analogue signal will be powerful enough to drive the two phones (i.e. shown as the Main and Extension phones). The total REN load is 2 based on two phones with a stated REN of 1. It's not clear what REN load is supported by the BT Home Hub 2, and indeed whether it is still relevant.
As @Ali_A kindly flagged, it seems the old analogue external bell won’t work with this new configuration. My understanding is that the bell previously took its power from the ~50V AC feed via the master socket capacitor during ringing. That will of course disappear under the digital arrangement. Is there any mechanism or gadget that could supply power for the bell? I suppose I could do the digital voice reinjection via a BT Digital Voice Adapter instead of the BT Home Hub’s analogue output - on the understanding that does provide a level of power - but it sounds like that only supports a REN of 2, and my network would presumably exceed that (two phones plus the bell). I’m therefore leaning towards the conclusion that the bell will have to go, and if that’s the case, then so be it.

As an aside, being new to BT’s FTTP configuration, I’ve learned that a power socket will be needed for the ONT. That’s awkward, as the current master socket is in a porch with no mains supply. For the current analogue setup, that works well and is neat and tidy, but for the switchover I gather (from various forum comments) that engineers aren’t usually keen to run fibre any further than necessary. Adding a new power socket in an old house with ancient wiring won’t be straightforward, and there’s the added issue of a long-since embedded phone cable entry point into the property that will be difficult to reopen. Still, that’s my problem to sort.

Re: Can Digital Voice work with this wiring?

WSH — Sat, 06 Sep 2025 08:41:01 GMT

Have you definitely been told it will change to FTTP? It is a popular misconception that DV and FTTP go together. In fact, DV will run quite happily over the old copper, so a change to DV does not necessarily involve a change to FTTP.

Re: Can Digital Voice work with this wiring?

john-tejada — Sat, 06 Sep 2025 09:10:26 GMT

That is my understanding.

From the BT email: "We're upgrading your service. Openreach is upgrading your service to Full Fibre Broadband at no extra cost. You'll also move to a Digital Voice home phone service."

And then: "We'll drill a small hole through the wall to connect the Fibre cable."

Re: Can Digital Voice work with this wiring?

WSH — Sat, 06 Sep 2025 09:12:30 GMT

Yes, that's clear enough.

Re: Can Digital Voice work with this wiring?

Anonymous — Sat, 06 Sep 2025 09:51:44 GMT

@john-tejada

There are modern electronic equivalents of the old extension bell. Have a look at "Geemarc Clearsound CL11 Telephone Ring Amplifier" for example. There are also replacement phones with extra loud ringers built in.

If you put the telephone number into the wholesale checker, the notes at the bottom of the page should give an indication of how FTTP would be provided. It may not necessarily follow the existing cable, especially if it's DIG (direct in ground).

BT Broadband

Re: Can Digital Voice work with this wiring?

pddco — Sat, 06 Sep 2025 15:35:15 GMT

@john-tejada Impressed that the LAN still worked okay with ringing current within the same Ethernet cable. Although I suppose it would only cause a temporary issue should there be data on the LAN coinciding with an incoming call.. But a rather neat cabling solution nonetheless. No harm in trying to see if the hub will move the old bell coils into action when you do get switched over to DV in any case.

Re: Can Digital Voice work with this wiring?

HHGTTG — Sat, 06 Sep 2025 17:48:49 GMT

We've discussed this before or at least I have asked that question but BT seem to insist that I have FTTP in order to have Digital Voice. I started getting copious emails from both BT and Oprenreach from about March onwards and at regular intervals saying 'we are upgrading you, at no extra cost to DV and Essentials FTTP' and giving me an installation date. Each time on the Openreach email I reject their offer as they give a link so to doe and they say OK, you'll remain on your existing service ( ADSL in my case). I shall keep on doing this until they won't allow me to do that. Why won't they give me DV over my ADSL connection?

Re: Can Digital Voice work with this wiring?

licquorice — Sat, 06 Sep 2025 18:11:58 GMT

DV is totally agnostic to how your broadband is delivered. It is just another IP stream, no different to accessing a website.

Re: Can Digital Voice work with this wiring?

pddco — Sat, 06 Sep 2025 20:05:57 GMT

@HHGTTG

Why not DV over ADSL? I’m thinking that Openreach may be wanting to also migrate broadband services off exchange based (ADSL) kit as part of exchange closures perhaps?

I know that in some areas people who have no broadband services at all - just a POTS - are being migrated to DV with essentially an exchange based ATA cut over to replace the PSTN termination. No visits or hubs needed. And still ‘exchange’ powered.

But at the end of the day it’s going to happen. If you’ve got Broadband and Phone over the Openreach access network you’re going to lose that ‘exchange’ powered landline.

Re: Can Digital Voice work with this wiring?

jac_95 — Sat, 06 Sep 2025 21:52:54 GMT

@HHGTTG

If you are in a Openreach Full Fibre (FTTP) priority area then the copper based services are being withdrawn.

More areas are now becoming an Openreach Full Fibre (FTTP) priority area and now this is also aligning and being combined with Digital Voice migration too.

Hence the required move to Openreach FTTP is combined with Digital Voice and vice versa.

You can check if you are in a Openreach Full Fibre (FTTP) priority area by going to https://www.broadbandchecker.btwholesale.com/#/ADSL/AddressHome

If you post the results (minus your address) but also include the footnotes it will help state if your in a Openreach Full Fibre (FTTP) priority area or not.

https://landlinesgo.digital/checkmyline also helps explain what the results means

Re: Can Digital Voice work with this wiring?

john-tejada — Sun, 07 Sep 2025 07:08:40 GMT

My summary is that my mother is in a fibre-first area with WLR being withdrawn. Digital Voice is mandatory for landlines. In theory she'll get up to 1 Gb/s through FTTP.

It also notes: "Residential OH Feed with no anticipated issues."

So, I think that means they'll run the fibre from the pole ("overhead"), and are assuming that they can follow the existing routing for the analogue wiring. That's not true as the current routing now runs under tiles that were added after the line would first have been put in place many years ago. It's not readily accessible.

Should I flag that in advance to Openreach (i.e. correct their "no anticipated issues" line)?

Also, how amenable is their engineer likely to be to customising the routing? Drilling through the wall at the location of the cable end-point on the property won't work. There is no power socket anywhere near, and running a power extension cannot be done easily without creating an untidy trip hazard for my mother.

My preference would be to run the fibre cable down the outside of the property, then through the wall of the foundations into the property, under the floorboards, and up through the floorboards into the other side of the entry room close to the power socket. The house is split level, so unusually, I can easily crawl through the foundations under the floorboards to organise cabling. That is how I fitted the long run of ethernet cabling that is represented in the wiring diagrams I posted. I would be at the property for the engineer's visit to do that. I imagine that would be the quickest way to do the installation, and also the cleanest.

Re: Can Digital Voice work with this wiring?

john-tejada — Sun, 07 Sep 2025 07:10:03 GMT

Thanks @Anonymous. That's a helpful recommendation. I'll probably look into getting something like that.

Re: Can Digital Voice work with this wiring?

john-tejada — Sun, 07 Sep 2025 07:19:46 GMT

@pddco Thanks for the reply. Yes, in my naivety when I originally laid that cable back around 2016, I didn't actually know that the bell wire carried power, let alone that it was of a relatively significant level. Rather, I was just approaching it all as a wiring puzzle! I only learned yesterday through Googling - and as you have kindly pointed out - that people advise against running the ring signal bundled with the ethernet signal into a single cable in the way that I have done. Still, it seems to have worked ok, albeit for the relatively light usage it has typically had.

I will see if the old bell coils do spring back to life after the FTTP installation, however I am doubtful. They are quite hefty mechnical things - not far off being a domestic equivalent of Big Ben - so I can't imagine they would get triggered.

Re: Can Digital Voice work with this wiring?

HHGTTG — Sun, 07 Sep 2025 08:03:35 GMT

@john-tejada

I'm in the same position as your mother in a way. Personally, I can only see Openreach doing the simplest of exterior routing to the CSP terminal. My current old master socket is in my long hallway just below the hall window overlooking the road. There is a small table here with an ordinary phone on it. There is no power socket below the table but only about 8 feet away down the side of the hallway where there is a wheeled trolley and table lamp etc. I would have to take a coloured extension lead from here back up the hall, past the front door and around a corner to reach the area near the old master socket and where the ONT would most like to be. The extension lead would have to go under the the interior door mat and be secured with a few clips. However, I would not want the Hub to be on the hall table in direct sun where it would bake in the Summer's heat and so I Have a long Ethernet cable available to run back from the Hub to the trolley where the Hub would be situated and also have power available from the mains socket below. A bodge I know but this is the only answer.

Like yourself, there is an alternative position in another room where there is power convenient for me but I cannot imagine OR threading and external fibre cable to that part of the house around many corners and front door that is at a right angle to the facing wall of the house.

Re: Can Digital Voice work with this wiring?

john-tejada — Sun, 07 Sep 2025 08:40:58 GMT

@HHGTTG

Yes, that sounds tricky. There will surely be many customers in a similar postion. It's a little frustrating.

On the CSP point, I had been wondering whether they would fit a CSP at my mother's house. I have read that they don't always do that, and instead sometimes go straight through the wall, then strip back the external cable. I think I'd prefer a CSP for neatness of wiring.

On your particular wiring dilemma, I did also read anecdotes on some forum posts about engineers sometimes being ok to run the internal fibre cable for up to 10m. I am guessing that could work for you in that you could run the fibre from the entry point, past the front door (under the mat), and then clipped along the hallway and round the corner to your power socket? Still, it's presumably at the discretion of whoever does the installation.

Part of my thinking is that if I can present the engineer with the quickest plan for what also happens to be the best solution, then he/she might be inclined to go along with it (and then get on their way to the next job as soon as possible).

Re: Can Digital Voice work with this wiring?

HHGTTG — Sun, 07 Sep 2025 09:06:27 GMT

@john-tejada

I can't imagine OR not fitting an external CSP box as that is where the connection is made to the internal, thinner cable and indeed is spliced there and where a few turn of excess cable is put.