The UK’s traditional analogue phone network is finally reaching the end of its life. By January 2027, the Public Switched Telephone Network (PSTN) – along with all remaining ISDN lines – will be permanently switched off. When that day arrives, anything still relying on copper lines will simply stop working.For many organisations, this goes far beyond the phone on the reception desk. Door entry systems, alarms, payment terminals, lift phones, fax lines, and older PBX equipment often depend on PSTN without anyone realising, which means the impact of doing nothing could be far more disruptive than expected.What’s particularly concerning is that around 500,000 UK businesses – mostly SMEs – still haven’t migrated as of early 2026, despite years of warnings and industry guidance. Half a million organisations are now heading towards a hard deadline, and the closer we get to 2027, the more pressure, cost, and operational risk they’ll face if they don’t act soon.Why is PSTN being switched off?
The PSTN is built on copper wires and analogue signalling, and while it served the UK well for decades, it’s now showing its age. Ofcom’s Connected Nations report highlighted a sharp rise in resilience incidents – up 45% in 2024 – which is a clear sign that the network is becoming increasingly fragile and difficult to maintain.
At the same time, the way businesses communicate has changed dramatically. We expect mobility, video calls, cloud access, collaboration tools, and reliable connectivity wherever we are, and the PSTN simply wasn’t designed for any of that.
To meet modern expectations, the UK is moving to an All-IP future, where every phone line becomes digital and calls are routed over Internet Protocol (IP) rather than copper. Once the switch-off happens, anything left on PSTN will be disconnected, and there won’t be a fallback option.
What about ISDN?
ISDN was once the “modern upgrade” that brought better call quality and new features to businesses in the 1980s and 1990s, but today it’s just as outdated as PSTN. It’s also being retired as part of the national move to digital, so any organisation still relying on ISDN will need to migrate too.
Is IP technology better?
IP-based telephony is designed for the way businesses operate today, giving you the freedom to make and receive calls on any device, from any location, using the same number. It allows your phone system to integrate seamlessly with your business applications – whether that’s your CRM, ticketing platform, collaboration tools, or video conferencing – so your communication becomes part of a wider, more connected workflow.
Because everything is hosted in the cloud, you can scale easily without investing in expensive on-site hardware, and you benefit from modern infrastructure that’s far more resilient and secure than the legacy network it replaces. In short, this isn’t just a like-for-like replacement for PSTN; it’s a genuine upgrade that opens the door to better productivity, flexibility, and reliability.
Cloud telephony vs IP telephony: what’s the difference?
Cloud telephony is a VoIP service hosted entirely online, which means you don’t need an on-site phone system or the maintenance that comes with it. It’s flexible, secure, cost-effective, and ideal for most SMEs who want a modern communication setup without the complexity of managing hardware.
IP telephony is the broader category that includes cloud telephony but also covers SIP-based solutions, which allow older PBX systems to connect to the digital network. If you still rely on legacy equipment, SIP can act as a bridge to keep your system running while you plan your longer-term move to the cloud. If you want simplicity and modern features straight away, cloud telephony is usually the best route.
Is the UK behind?
The UK isn’t dramatically behind, but other countries have moved faster. Estonia and The Netherlands have already switched off PSTN entirely, and Germany, Japan, and Sweden are well ahead in their digital migrations. The shift to digital is happening everywhere, and the UK is now catching up.
Why 500,000 SMEs are at risk
With so many businesses still relying on PSTN or ISDN, the biggest challenge is time. As we move closer to the switch-off date, demand for engineers, providers, and installers will surge, and the industry simply won’t have the capacity to support everyone at once. That means businesses who wait until late 2026 or early 2027 may face supply bottlenecks, rushed decision-making, and higher costs – especially if emergency work is needed to keep critical systems running.
There’s also the risk of unexpected downtime. Many organisations don’t realise how many devices are still connected to copper lines, and if alarms, card machines, lift phones, or access systems fail without warning, the consequences could be serious. For SMEs, where every hour of disruption matters, this is a risk that’s entirely avoidable with early planning.
Why you should start preparing now
Migrating away from PSTN isn’t just a phone upgrade; it’s a review of everything in your business that touches a phone line. That includes alarm systems, door entry and access control, payment terminals, lift phones, fax lines, legacy PBXs, and any other device using a copper connection.
Many organisations have already embraced cloud communications, internet calling, and video collaboration, but thousands haven’t, and the switch-off will affect them all. Starting now gives you the time to audit your systems, understand what needs to change, and plan a smooth transition without pressure or disruption.
What should you do next?
If you’re unsure what your business is still running on PSTN, the first step is simply to audit your lines and connected devices. Once you know what you’ve got, you can decide whether you need a full move to cloud telephony, SIP connectivity for existing equipment, or a hybrid approach while you transition.
You may also need to review alarms, access systems, and other analogue devices to make sure they’ll continue working after the switch-off. The important thing is not to wait. The switch-off is coming, and the sooner you prepare, the smoother and more cost-effective your transition will be.
Frequently asked questions about the PSTN switch-off
When exactly will PSTN and ISDN be switched off?
The national switch-off is planned for January 2027. From that point onwards, PSTN and ISDN services will no longer be available, and any lines or services still relying on copper-based analogue connectivity will stop working. Some areas may see changes earlier as providers phase out services region by region, so it’s wise to treat 2027 as the final deadline, not the starting point.
What happens if my business doesn’t migrate in time?
If you don’t migrate before the switch-off, any services still running on PSTN or ISDN – including phones, alarms, door entry systems, lift lines, and payment terminals – may stop working without warning. You could face downtime, emergency call-outs, and rushed decisions about replacement solutions, all of which tend to be more expensive and more disruptive than a planned migration.
Why is the switch-off particularly risky for SMEs?
Around 500,000 UK businesses, mostly SMEs, have yet to migrate as of early 2026. Smaller organisations often have limited IT resources and may not realise how many systems still depend on PSTN. Leaving it late increases the risk of downtime, unexpected costs, and compliance issues, especially where monitored alarms or access systems are involved. Early planning gives SMEs the chance to choose the right solution, at the right price, without pressure.
Is cloud telephony always better than keeping my existing phone system?
If you don’t migrate before the switch-off, any services still running on PSTN or ISDN – including phones, alarms, door entry systems, lift lines, and payment terminals – may stop working without warning. You could face downtime, emergency call-outs, and rushed decisions about replacement solutions, all of which tend to be more expensive and more disruptive than a planned migration.
How do I know which of my systems still rely on PSTN?
The best starting point is a simple audit. List every phone line you pay for and every device connected to those lines, including desk phones, fax machines, alarms, door entry systems, lift phones, and payment terminals. Your telecoms provider or IT partner can help you identify which services are still analogue and advise on suitable IP or cloud-based replacements, so you can move in a controlled, planned way rather than reacting at the last minute.