The UK’s copper-based PSTN and ADSL network will be switched off on 31 January 2027.
What I said was accurate. This deadline affects Openreach PSTN services only, mostly BT/EE/Plusnet customers as well as some smaller providers who would resell it. There is no singular PSTN or ADSL network. In practice the industry is trying to shift all customers over to "digital voice" because a) it's cheaper to provide and b) it is necessary for customers who switch to full fibre.
In a small number of cases (such as for vulnerable customers without broadband), they will move to a "pre digital phone line" which uses new equipment in the exchange but otherwise behaves the same as it always did.
BT Wholesale ADSL, LLU (Sky/TalkTalk/etc) and other copper exchange based services are totally unaffected. Openreach is pursuing a totally separate programme to close around 4500 of their 5500 exchanges which will set an eventual end date for these services
How does this work? Did those providers have to install their own equipment within and alongside BT stuff in every exchange throughout the country?
I think a DSLAM is the kind of equipment we're talking about for sure: for seprating analogue voice from broadband data, modulating the data onto a different medium and presumably doing some kind of packet routing. But I'm more curious about the scale of physical infrastructure belonging to those third party providers. Did they lay a backhaul network between thousands of exchanges?
Exactly that. They rent space in the exchange and then rent copper lines from Openreach for each customer they serve. In most cases the DSLAMs also provided the phone service as well. For "fibre to the cabinet" they'd still use their exchange equipment for the phone service and pay Openreach to provide the broadband service.
Openreach stopped selling new PSTN services in 2023, and as such new customers would be directed to take broadband only. Plusnet doesn't offer a "digital voice" service like BT and EE do. Customers who wanted to keep a landline service would have had to go with another provider.
Anyway - it feels like we're getting a bit off topic here