If you’ve heard people talking about “the PSTN switch off” and thought it sounded technical, confusing, or like something only telecoms providers need to worry about? You’re not alone.
This change affects most UK businesses, even those with very simple phone or broadband setups.
You don’t need to understand telecoms jargon to understand why it matters – and that’s exactly what this guide is here to explain.
What is PSTN, in simple terms?
PSTN stands for Public Switched Telephone Network, but you can forget the acronym almost immediately.
In plain English, PSTN is the old copper phone network. It’s the system that has powered traditional landlines in the UK for decades.
If your business has ever had a phone plugged into a wall socket with a dial tone, that service almost certainly ran over PSTN.
What many business owners don’t realise is that these same phone lines are often used for more than just calls.
Over the years, PSTN quietly became the backbone for things like alarm systems, telecare systems, card payment machines, door entry systems, fax lines and even some older broadband services. Because these systems have “just worked” for years, they’re easy to overlook.
That’s why the PSTN switch‑off often catches businesses by surprise.
What does the PSTN switch‑off actually mean?
The PSTN switch‑off means the UK is permanently turning off this old copper network.
The final switch‑off date is 31 January 2027. After that point, PSTN and ISDN services will no longer work. This isn’t a policy change or a contract decision – it’s a physical network being retired.
It’s also important to understand that this isn’t something individual providers can delay or opt out of.
It’s a nationwide programme led by Openreach as part of the move to a fully digital network. Any service still relying on PSTN after that date will simply stop working.
Why is PSTN being switched off?
The short answer is that the network is no longer fit for modern use.
The copper infrastructure behind PSTN was designed long before internet‑based communication existed. It’s becoming increasingly difficult and expensive to maintain, and it can’t support the flexibility businesses now expect.
At the same time, the way we communicate has changed. Calls no longer need dedicated copper wires – they can run over an internet connection instead.
That’s why the UK, along with many other countries, is moving to digital voice services as the long‑term standard.
Why the PSTN switch-off matters to your business
This change isn’t just about desk phones. For many businesses, a single phone line supports several critical services.
It’s common to discover that PSTN is still being used for things like card payments, security alarms or entry systems – often without anyone realising.
Services that may be affected include:
- Traditional landline phones or older phone systems
- Alarm and security systems that “dial out”
- Card payment machines and EPOS terminals
- Door entry systems and intercoms
- Fax lines and lift emergency phones
- Older broadband services such as ADSL or some FTTC connections
If these aren’t identified and updated in time, the impact can be immediate.
Phones may stop ringing, payments could fail, or safety systems may no longer communicate as expected. This risk is often greatest for smaller organisations, where one line supports multiple services.
You can learn more about services that may be affected here.
Has the PSTN switch-off already started?
Yes – and this is an important point.
Since September 2023, Openreach has stopped selling new PSTN and ISDN services.
In many areas, businesses can no longer add, change or move traditional phone lines and are instead directed towards digital alternatives.
This is why some organisations only become aware of the PSTN switch‑off when they move office, renew a contract, or try to upgrade their broadband or phone system. By then, staying on PSTN is no longer an option.
What replaces PSTN?
PSTN is being replaced by digital phone services, where calls are delivered over an internet connection rather than copper wires.
You may hear these described as VoIP (Voice over Internet Protocol), cloud phone systems, or Microsoft Teams Phone. While the technology behind them is different, the experience for callers is familiar – and often better.
In most cases, existing phone numbers can be kept, and staff can take calls from desk phones, mobiles or laptops if needed.
For many businesses, this isn’t just a replacement – it’s an upgrade.
Do I need to act now?
There’s no need to panic, but it’s not something to ignore.
Businesses that leave this too late risk rushed decisions, limited engineer availability, or discovering problems only when a service stops working.
Those that plan early have time to understand what’s affected, choose the right solution, and make the transition with minimal disruption.
Talk to ITC Service about Modern Telephony Solutions
Are you concerned about the switch? Looking for more information? Reach out to our team. We’ve got over 20 years of experience helping businesses find the right phone system for them.
Whether you want advanced reporting, clever integrations, or just something simple and robust that works. We have a phone system for you.
Even if you’re unsure whether this applies to you, a conversation with our team now can save a lot of pressure later.
Frequently Asked Questions
When is the PSTN switch-off happening?
The UK PSTN and ISDN networks will be switched off on 31 January 2027. After this date, services relying on them will no longer function.
Does this affect small businesses?
Yes. In many cases, small and medium businesses are more affected because a single phone line may support phones, card machines or alarms at the same time.
Will I lose my phone number?
Usually not. In most cases, business phone numbers can be transferred to digital systems, meaning customers won’t notice any change.
How do I know if my business is using PSTN?
If your bills mention line rental, PSTN, ISDN or analogue lines – or if you have older alarms, card machines or fax lines – it’s worth checking. Many dependencies aren’t obvious.
Is VoIP reliable enough for business use?
Yes. Modern digital phone systems are widely used across the UK and are designed to be reliable, flexible and suitable for hybrid working when paired with the right connectivity.
What happens if I do nothing?
If a service still relies on PSTN after January 2027, it will stop working. There’s no fallback once the network is switched off.
The PSTN switch-off in simple terms
The PSTN switch off-isn’t about complicated telecoms jargon. It’s about making sure your phones, payments and safety systems continue to work.
With a bit of planning, most businesses find the move straightforward – and often beneficial.
If you’re looking for a partner to help you navigate the PSTN switch off, why not speak to our team today?
