I lost my DV telephone signal yesterday (internet still worked oddly all blue lights on front of Smart Hub 2) for about 12mins.
I noticed immediately as the telephones light up.
I see when visiting Digital Voice: I have a problem with my service it starts of OK with testing/reporting a fault but then goes into a broadband fault and you can't really move forward.
I did quickly divert my landline through this web link https://my.bt.com/s/apps/appsvoicemanagement/#/calldivert?acckey=26330503&product=digitalvoice&redir... (I keep that link on my mobile).
Bit disappointing this even for 12mins and it makes me think I can't really trust my landline. I do use a UPS obviously but that's of no use here as it wasn't a power related problem.
Based on my past experience with the old BT Broadband Talk service, I would not be surprised. That used to fail quite often, and it took ages to get fixed. That was a VOIP service running to remote servers, and if any part of the routing dropped, the phones failed.
The main issue was it offered low cost calls, but if it failed, the phones reverted to the normal landline, and calls were charged at full rate, and people were unaware. I suspect that issue, and some security issues, let to the closure of the service.
I cannot see DV being any different, its never going to reliable as a fixed copper connection connected to exchange equipment.
After Broadband Talk was pulled, I switched to another provider, I can honestly say in the 10 and a half years I have been with them, I have had had two service outages, both of which were flagged via txt message and email as soon as they occured. Both were resolved within a reasonable time frame, communication was excellent throughout and compensation was offered. Much cheaper than BT and I have happily recommended them a number of times to people over the last decade. Can also use your own choice of VoIP phone or smartphone app with no hassle. There are other options out there which "just work".