By the time you finish reading this, Openreach will be roughly a thousand customers closer to retiring the copper phone network. They're doing about 25,000 a week. The full switch-off is January 2027.
If you've got a landline — even one you never use — this affects you. Same goes for your house alarm if it dials out over the phone line, your careline pendant if you've got one, and any old fax machine still chugging away in a back office somewhere.
I've been on the BT/Openreach network for over twenty years. This is the biggest single change to UK telephony since the GPO became British Telecom. And most people I see on the doorstep haven't been told properly. So here's the real version.
What the PSTN actually is
PSTN stands for Public Switched Telephone Network. It's the copper phone system — wires that run from your house to a green street cabinet, then on to a BT exchange somewhere a few miles away, and from there into the rest of the world. It's been the spine of UK telephony since the early 1900s.
It works on analogue voltage. Pick up the handset and you complete a circuit. The exchange knows you're there. Dial tone arrives down the same pair of wires. Since the late 1990s, that same pair has also been carrying broadband on top of voice, using ADSL or VDSL frequencies above the audio band.
The PSTN is old. Some of the gear in BT exchanges is older than I am. Spare parts are scarce. The engineers who actually knew the analogue equipment inside-out are mostly retired. And maintaining a country-wide copper network is a huge ongoing job for Openreach. So they're switching it off.
When is it actually happening
January 2027 is the hard deadline. Openreach is migrating customers across in waves right now, area by area. Once your area is migrated, you can't get a new analogue line — doesn't matter who you sign up with. New customers get a digital service from day one.
If you're already a customer, your provider — Sky, BT, TalkTalk, Plusnet, Vodafone, whoever — is supposed to write to you with a date, a replacement product, and any new hardware you need (usually a VoIP-capable router). In practice, the letters are vague, the replacement is "automatic", and most of them end up in the recycling.
If you live in London and you're still on a traditional landline, you've probably already had at least one of those letters. If you haven't, you will. Soon.
What it means for your landline
Your phone number doesn't change. The handset on the hallway table doesn't change. What changes is what carries the voice from your house to the exchange. Instead of analogue voltage down a copper pair, the voice runs as digital data over your broadband connection.
That has three knock-on effects worth knowing.
You need mains power. A traditional copper line gets a tiny voltage from the exchange and keeps working in a power cut. A digital voice service runs through your router, and the router needs mains electricity. No power, no phone. Vulnerable customers can ask their provider for a battery backup unit — it usually gives an hour or so of dial tone after the lights go out.
You need broadband that actually works. If your broadband drops out, your phone drops with it. So all those niggling broadband faults nobody bothered fixing — they matter more now.
Your handset gets plugged into the router, not the wall socket. Most providers give you an adapter — you plug your existing phone into a port on the back of the router. Or they send a new cordless base station that's already paired. The phone itself doesn't need replacing in most cases.
What it means for alarms, carelines and lift lines
This is where it gets serious, and where I think a lot of London is going to get caught out. Burglar alarms that dial 999 over the phone line, lift alarms that dial out from inside the cab, careline pendants for elderly people — they all assume an analogue line that's always there.
Pat in Bermondsey is the reason I won't shut up about this. Her daughter rang me on a Saturday morning in a panic — Pat's careline pendant had stopped working because her phone line was dead. The dropwire from the pole had snapped in the wind. I was twenty minutes away and got there by 11. Jury-rigged a temporary connection on the surviving pair and got the careline talking again, then reported the broken dropwire to Openreach for proper repair the following week.
Pat would have waited five days for Openreach on her own. Now imagine that same call, in 2027, on a digital line, in the middle of a power cut, when the router's been off for three hours. That's the scenario every London council needs to be planning for, and most aren't.
If you've got a careline pendant, ring the company who supplied it — Telecare 24, Lifeline, your borough council's telecare team, they all use different brands. Ask one question: "Is this device compatible with digital voice, and what happens during a power cut?" The answer should include a battery backup or a mobile-network fallback. If they fudge it, push.
Same conversation for monitored burglar alarms. The signalling path from your alarm panel to the monitoring centre might still be on the phone line. Your installer needs to either keep it going (with a battery backup) or move it onto a mobile-signalling path. Most modern alarm boards have a SIM slot for exactly this — but if your panel is more than ten years old, it might not.
Fire-alarm panels in commercial buildings, lift phones, door-entry handsets in blocks of flats — same conversation needs to happen with the building's managing agent. Don't assume someone else has already had it.
What it means for your broadband
If you're already on FTTP (full fibre — the kind where Openreach put a small white box on the wall in your hallway and ran a fibre cable into it), the switch-off doesn't change much for you. You're already past the copper bit.
If you're still on FTTC — your master socket is connected by copper to a green cabinet at the end of the street, and broadband is carried over that copper — then that copper is going. Your provider will migrate you to FTTP if Openreach has installed fibre to your address, or to a 4G/5G mobile alternative if they haven't.
Most of London now has FTTP coverage, but it's patchy. Some streets have it, the next street over doesn't. Check Openreach's online availability checker for your postcode. If FTTP shows green, you're sorted. If it's amber or red, your provider has to find another solution before they pull the copper.
What you should do now
- Find a recent letter from your phone or broadband provider mentioning "digital voice", "digital phone", or "the PSTN switch-off". If you can't find one, ring them and ask when your area is being migrated.
- Decide whether you actually use the landline. If you haven't picked up the handset in three years, you might not want to keep paying for it just because it's always been there. Number portability still works — you can keep a number for years on a SIM if you want it for sentimental reasons.
- Make a list of everything that uses the phone line passively. Alarms, telecare, lift lines, fax, building intercoms. Pass it to the relevant installer for each one.
- Check on elderly relatives. If your parent is on an analogue line, ring their provider yourself and confirm the migration plan. Don't assume they've understood the letter — most of them haven't, and that's not a criticism.
- Ignore anyone cold-calling about "PSTN switch-off support". Big scam season right now. Your provider is already obliged to handle the migration for you under Ofcom rules.
Mrs Okonkwo in Lewisham still rings me about her phone — same number since 1971 and she's not letting it go. Last year I swapped out the crackly old BT junction box on her outside wall — the rubber seal had perished, water in the terminals, classic. Replaced it, ran a new internal cable through the skirting to a fresh NTE5c. About 90 minutes.
This year, her provider will give her a digital adapter that plugs into the router and connects her existing handset. The number stays. The handset stays. The wire from the wall to the handset stays. Only the thing in the middle changes. That's what every customer needs to hear: nothing about your day-to-day phone use is going to feel different, as long as the migration is done properly.
If you want a hand
I get called out for two kinds of switch-off jobs at the moment. The first is people whose internal wiring is so old and dodgy that the digital voice service won't work reliably over it — old bell-wire extensions, scotchlok joints, surface-run dropwires from the 1970s. We rip that out and replace with a clean run on Cat5e or Cat6 from the router location to wherever the handset lives.
The second is people with non-obvious bits of kit on the line — fax machines in solicitors' offices, alarm panels in basement plant rooms, telecare units in housing-association flats. Those need to be tested against digital voice before the switch happens, not after. I'll do the test on a separate adapter so we know it works before your provider migrates the live line.
If you're not sure what's hanging off your line, ring me on the number below and describe what you can see in the master socket. Two minutes on the phone usually sorts it.
Common questions
Do I lose my landline number?
No. The number stays. What changes is the route — your voice travels over broadband instead of through the analogue exchange. The migration is done by your provider with your number kept intact. If anyone tells you otherwise, ring your provider directly.
Will my phone work in a power cut?
Not by default. A copper line gets a small voltage from the exchange and works without mains. A digital voice line runs through your router, which needs mains. If you, or someone in the household, is vulnerable — elderly, dependent on a careline, etc — request a battery backup unit from your provider. It'll give you about an hour of dial tone after the power goes.
What about my house alarm or careline pendant?
Ring the installer or supplier and ask the direct question: "Is this device compatible with digital voice, and what's the plan during a power cut?" If the device uses the analogue line to dial out, it'll need either a battery backup or a switch to mobile signalling. Don't assume.
Do I need to pay for the migration?
No. The migration itself is handled by your phone/broadband provider under Ofcom rules. Anyone cold-calling offering "PSTN switch-off support" or "compulsory line upgrades" is a scam. Hang up and ring your real provider on a number from their website if you want to check.
What if my broadband isn't fast enough for digital voice?
The bandwidth needed for a voice call is tiny — about 100 kbps. Any working broadband will handle it. The bigger issue is whether your broadband is stable. Drop-outs that you used to tolerate ("oh, it just goes off for a minute every now and then") will now be drop-outs in your phone service too. Worth getting any underlying line issues fixed before the migration.
Got a question about your line?
If you're not sure what's hanging off your phone line, what the letter from your provider actually means, or whether your alarm/careline will survive the switch — ring me. Two minutes on the phone usually answers it.