We must also remember that the OP has said IP based solutions are no good as the internet connectivity in his area is awful. The whole of the UK is supposed to be wired for fibre connectivity so BT can turn the copper phone system off in 2025ish. Although thats bound to slip - there is no way every unserved property across the country is going to be done by the target date
BiB - BT/Openreach's plan is to switch off the POTS system by the end of 2025 - this isn't dependent on connecting all current premises with fibre to the premises, indeed it would take a monumental amount of swift progress if they were to achieve this target in the next 36 months.
According to ThinkBroadband.com's figures, they estimate that Openreach have now covered over 9 million premises with FTTP availability, which combined with KCOM in the Hull area makes it ~30% of premises at present. If you also factor in FTTP from all available providers (inc. Virgin & Alt-Nets) around 45% of UK premises can get an FTTP connection. Add Virgin Media's DOCSIS network and the amount of premises that can get a gigabit-capable download connection is ~73%.
But back to Openreach - the plan is that when their POTS network is switched off, anyone wishing to retain a "landline" service will need to do so through a VoIP capable service. This is already done for FTTP connections that want such a service, as well as some copper line connections already. Post-POTS switch off a modem/router will need to be used (in most cases provided by an ISP) that will effectively act as the "master socket" of such a connection. AIUI Openreach either already have or are putting in place a 0.5 Mb/s symmetrical speed tier to ISPs where a customer only wishes to have a landline phone connection to support VoIP - I'd guess in theory there would be nothing to stop a customer using such a connection for internet surfing even if these days such speeds will give a very limited experience, though not a problem for VoIP which even at more bitrate demanding codecs can run within the 0.5 Mb/s confines quite easily.
However, a firm date is up in the air at present due to the conumdrum of power fall back to such customers when there is a local power outage. At present in the POTS system the phone lines stay powered through -48V DC from the exchange's battery backups but of course this isn't present in FTTP connections, and in POTSless copper pair connections (xDSL only connections) such a DC voltage isn't needed. This however leaves such customers without a landline connection during power outages unless they have a battery backup in place. Such BBU's were installed during the very first FTTP connections but in the last few years Openreach no longer provide them. My guess on how this will be solved will be for a BBU to be offered at installation, inc. either for free or discounted for certain people (vulnerable people, those in areas with no mobile coverage etc.) while others will be offered a BBU for a price via their ISP.
As it is, I have to say that Openreach's progress in Nothern Ireland with it's FTTP roll out has been very good, I think it's around 85% of premises here can avail of an FTTP connection. I'm already on one myself but on a 40/10 speed profile (I don't really need much more than this) and while I rarely use the landline, I have it setup using a third-party provider with the modem/router I use. The big problem for Openreach here will be trying to serve the last 5-10% or so of premises - there's a significantly bigger percentage of the population in NI that live in rural areas (inc. "one-off" housing or some small isolated housing estates) compared to GB, and a large amount of them aren't well served via xDSL.
