The UK's traditional phone network - the analogue and ISDN lines that have carried calls for decades - is being switched off by Openreach on 31 January 2027. After that date, any phone, alarm or device still relying on those copper-based services will stop working. If your business uses analogue lines or ISDN, you need to move to an internet-based phone system before then, and 2026 is the year to do it.
There's nothing you have to do this week. But this is a fixed deadline, not a soft target, and it reaches further than most business owners expect. Here's what's actually happening and how to work out whether it affects you.
What is the PSTN, and why is it being switched off?
PSTN stands for Public Switched Telephone Network. It's the old copper-line system behind ordinary analogue phone lines and ISDN, the business version sold as ISDN2 or ISDN30. The technology goes back to the 1980s and earlier. Spare parts are getting harder to source and the whole network is expensive to keep running, so Openreach is retiring it and moving everything onto services that run over the internet instead.
The original target was December 2025. It was pushed back to 31 January 2027 to allow more time for the tricky cases like care alarms and lift phones. That extra breathing room is genuinely useful, but it isn't permission to wait until the last minute.
You can't buy new copper lines any more
A national "stop-sell" has been in place since September 2023. You can no longer order new analogue or ISDN lines, and in many cases you can't modify an existing one either. If you tried to add a line to your office recently and were quietly moved onto something digital, this is why.
There's a financial nudge too. Openreach is raising wholesale charges on legacy copper lines in stages through 2026, with the cost roughly doubling by the autumn, so staying put gets steadily more expensive.
It's not just your phone calls
This is the part that catches people out. Plenty of everyday equipment quietly uses an analogue phone line in the background, and much of it will stop working overnight if it isn't dealt with. None of it announces itself either. An alarm signalling over copper can fail silently, with nobody the wiser until the day it's needed.
Things worth checking around your building:
Lift emergency phones - the help button in a lift is a legal safety requirement and usually runs over an analogue line
Intruder and fire alarms that dial out to a monitoring centre
Door entry and access control for gates and barriers
CCTV that uses a phone line to send footage or alerts
Card payment terminals - some older models still dial out over analogue
Fax machines, franking machines and some EPOS tills
Care alarms and pendant alarms anywhere with vulnerable people
If any of these apply, start with an audit. Walk the building, see what's plugged into a phone socket, and ask each supplier or installer whether the device is ready for an internet connection or needs replacing. For lifts and life-safety systems in particular, don't leave it late. Replacement parts and engineer visits get booked up fast as the deadline approaches.
What replaces it?
The new services are IP-based, which simply means calls travel over your internet connection rather than a dedicated copper line. For most businesses it comes down to one of a few options:
VoIP / cloud telephony - a hosted phone system where the handsets and call features live in the cloud. You keep desk phones if you like them, but there's no physical exchange line
Microsoft Teams Phone - if you already use Microsoft 365, you can make and take external calls straight from Teams, which suits hybrid and remote teams well
Mobile or SIP-based alternatives for specific devices such as alarms and lift lines, usually fitted by the equipment's own installer
For most small offices around Berkshire and Oxfordshire, moving to cloud telephony or Teams Phone also tidies up the monthly bill by removing the per-line ISDN rental. Calls between sites and staff become free, and adding or removing a user is a settings change rather than an engineer visit.
Will we lose our phone number?
No. This is the most common worry and it's almost always fine. Established numbers can be ported (moved) onto the new service, including your main 0118 or 01865 number and any direct dials your customers know. Porting takes a bit of planning and coordination, but you keep the numbers printed on your vans, your website and ten years of business cards.
Your phones now depend on your broadband
Once calls run over the internet, your phone system is only as reliable as your connection. For most businesses that's a fair trade, but it does change what counts as a good enough connection.
Worth reviewing before you migrate:
Resilience - is there a backup if the main line drops? A 4G/5G failover or a second connection keeps the phones alive during an outage
Bandwidth - voice itself uses very little, but it competes with everything else on the line, so a busy office on a slow connection can suffer poor call quality
Power - an old analogue handset often kept working in a power cut. IP phones won't unless you've planned for it, which matters most for lifts and alarms that may need their own resilient setup
What to do in 2026
The biggest practical risk with this deadline is the bottleneck. Hundreds of thousands of UK businesses are migrating in the same window, and engineers and porting slots are finite. Leave it to late 2026 and you're queuing behind everyone else who also left it late.
Check your phone and line bills for terms like analogue line, PSTN, WLR, ISDN2 or ISDN30. If you see them, you're affected
Audit the building for non-phone devices on analogue lines - lifts, alarms, door entry, card machines, CCTV
Decide on your replacement - cloud VoIP, Teams Phone, or a mix - based on how your team actually works
Confirm number porting for every number you want to keep
Review broadband resilience and power so the new system holds up when you need it
Book the migration with time to spare, ideally well before the autumn 2026 rush
If you're not sure what you're paying for or what would suit your office, this is the sort of thing our team handles day to day. We can read your bills, audit the lines and devices in your building, and plan a switch that keeps your numbers and avoids the last-minute scramble. Dig out the bills, and if the wording is baffling, send them over and we'll tell you plainly where you stand.