The PSTN switch off UK 2027 is a major change that will affect every business still using traditional phone lines. From 31 January 2027, the Public Switched Telephone Network (PSTN) will be permanently switched off, meaning any system relying on copper-based landlines will stop working.
For businesses, this isn’t just a technical upgrade it’s a necessary shift to modern, internet-based communication systems like VoIP and cloud telephony. If no action is taken, critical services such as phone lines, alarm systems, and payment terminals could be disrupted.
This guide explains what the PSTN switch off means, which systems are affected, and how your business can prepare for a smooth transition before the deadline.
What Is the PSTN Switch Off in the UK
The PSTN (Public Switched Telephone Network) is the traditional copper-based phone system that has supported landlines for decades. The PSTN switch off refers to the UK-wide plan to retire this network and replace it with modern, internet-based communication systems.
The reason for this shift is simple. The existing infrastructure is ageing, costly to maintain, and no longer meets the needs of modern businesses. Digital alternatives offer more flexibility, better performance, and access to advanced features that traditional systems cannot support.
In practical terms, the switch off means:
- Traditional landlines will stop working
- Businesses must move to digital phone systems
- Communication will shift to internet-based services
For example, if your business still depends on a standard office landline, it will no longer function after the switch off unless it has been upgraded to a digital solution.
Plan before the deadline
When Is the PSTN Switch Off and What Happens Next
The full closure is scheduled for January 2027 but the groundwork has been laid for some time already.
A stop-sell restriction is already in effect across most of the UK. Telecoms providers cannot sell new PSTN or ISDN-based services. If you have tried to add a traditional line to your premises recently, you may have run into this already without fully understanding why.
Here is what the current position means in real terms:
- New traditional line services cannot be purchased in most areas
- Lines you already have will keep working until January 2027 after that, nothing
- Leave it too late and you will be competing with every other business that also left it too late fewer providers available, higher demand, tighter timescales
Businesses moving now have room to think it through properly. Businesses that wait until mid-to-late 2026 will be making fast decisions under pressure, and that rarely goes well.
What Systems Will Stop Working After PSTN Switch Off
This is where a lot of businesses get caught out they assume the switch off is purely about desk phones and do not look any further. In reality, the traditional network touches far more of your day-to-day operations than most people realise, often in ways that are not immediately obvious.
Things commonly running on PSTN include:
- Office landlines and on-premise PBX systems — the most apparent, but not the only issue
- Business broadband — some internet connections still run over PSTN infrastructure, particularly in older premises
- Security and alarm systems — many commercial alarms use a phone line to reach monitoring centres
- Door entry and access control systems — older intercom panels and access systems often rely on analogue lines
- Card machines and payment terminals — some EPOS setups still use traditional phone connections to process transactions
- Lift emergency phones — legally required in many buildings, and frequently wired into the PSTN
A good starting point is to walk through your premises and ask a simple question: what in this building makes calls, receives calls, or dials out on its own? Whatever comes up on that list needs to be looked at before 2027.
What Are the Alternatives to PSTN?
The main replacement technology is VoIP Voice over Internet Protocol. Rather than routing calls through copper wires, VoIP sends voice data over a broadband connection. It has been around in business environments for years and is now the standard approach to telephony for organisations of all sizes.
Depending on the needs of your business, the options broadly fall into three categories:
- Cloud-based phone platforms — hosted entirely off-site, with no hardware on your premises to manage or maintain
- Unified Communications platforms — solutions that bring calls, video, messaging, and team collaboration together in a single environment
- Microsoft Teams Phone System — increasingly the preferred route for businesses already embedded in Microsoft 365
Which of these makes sense depends on how large your organisation is, how your teams are set up, and what you actually need your communications to do. What every business shares, regardless of size, is the need to make a move before the deadline.
Explore modern phone systems
Why Businesses Choose Microsoft Teams Phone System
For any business already working within Microsoft 365, Teams Phone System tends to be the obvious direction of travel. The appeal is straightforward: rather than introducing a separate communications platform that your team has to learn and switch between, Teams Phone builds full external calling directly into the environment your staff already work in every day.
There are some meaningful practical advantages here.
Everything your team needs calls, video meetings, group chats, shared files lives in one place. People are not jumping between applications or losing track of context when a conversation moves from a Teams chat to a phone call.
Staff can take and make calls on whatever device they are working from: a laptop, a mobile, or a desk phone. It does not matter whether someone is in the office, at home, or travelling. They remain reachable on the same number throughout.
Incoming calls are managed properly. Auto attendants, call queues, and routing rules mean customers reach the right person without being passed around unnecessarily.
The system connects with your existing Microsoft 365 tools and, in many cases, your CRM so the person answering a call already has some context before they pick up.
And when your business grows, adding new users or opening new locations does not require new hardware or a significant outlay. You adjust what you need and carry on.
For businesses thinking seriously about the transition ahead of the PSTN switch off, Teams Phone is worth careful consideration — not because it simply replicates what you are losing, but because it meaningfully improves on it.
PSTN vs VoIP Key Differences
For anyone who wants a straightforward comparison rather than a technical deep-dive, here is how the two approaches differ in day-to-day terms:
| Area | PSTN (Traditional) | VoIP / Cloud Phone |
|---|---|---|
| Technology | Copper-based phone lines | Internet-based calling |
| Flexibility | Tied to a fixed location | Works across devices and locations |
| Features | Basic voice calls | Advanced features, analytics, integrations |
| Scalability | Slow and costly to expand | Scales easily as your business grows |
| Maintenance | Ageing infrastructure, increasing costs | Cloud-managed, lower ongoing overhead |
| Remote working | Limited support | Built for hybrid and remote teams |
It is worth noting that switching is not just a matter of keeping the lights on. Most businesses find they end up with considerably more capability than they had before tools they simply did not have access to on a traditional landline.
How to Prepare for the PSTN Switch Off: A Practical Approach
Businesses that handle this well tend to treat it as a proper project with a timeline and clear ownership. Here is a sensible way to approach it.
Step 1 — Audit your current setup Get a full picture of every phone line, connected device, and service that might be running on PSTN. Think beyond obvious handsets — include alarm systems, broadband connections, card machines, and anything that makes automatic outbound calls.
Step 2 — Work out what actually needs replacing with a clear inventory in hand, you can assess each item in turn. Some older equipment can be adapted with a relatively inexpensive analogue telephone adaptor. Other devices will need to be replaced altogether. Knowing which is which early on saves a lot of stress later.
Step 3 — Evaluate your options carefully Price will be a factor, but it should not be the only one. Think about how well the solution fits your team’s actual working patterns, what happens when something goes wrong and you need support, and whether the platform is genuinely capable of scaling alongside your business over the next several years.
Step 4 — Build a realistic migration timeline Count backwards from January 2027 and allow proper time for testing, staff training, and sorting out any issues that come up before they start affecting live operations. There is no need to rush this if you start soon.
Step 5 — Test everything before going live Call quality, routing rules, voicemail, integrations — test all of it properly before you switch over. An issue caught during a planned testing phase takes a fraction of the time to fix compared to one discovered on a busy trading day.
Get ready for migration
FAQ's
1. Will my business phone stop working if I do nothing?
Yes without any changes, any system running on PSTN or ISDN will be non-functional after January 2027. This is not something that can be deferred indefinitely.
2. Can I keep my existing business phone number?
In most cases you can. Number porting lets you carry your current numbers across to a new provider, so there is no disruption from your customers’ perspective.
3. How do I know if my system is affected?
If you use a standard landline, an older on-site phone system, or anything that makes outbound calls over a phone line, it is very likely PSTN-dependent. An audit of your setup will confirm the specifics.
4. Is Microsoft Teams a viable replacement for a traditional phone system?
Yes. Microsoft Teams Phone System supports full external calling inbound and outbound and functions as a complete replacement for PSTN-based telephony. Most businesses find it offers considerably more than what they had before.
5. What if some of my devices cannot connect via VoIP?
Some older equipment can be connected using analogue telephone adaptors. Others may need replacing entirely. Which category applies to your specific equipment will become clear during your audit.
Final Thoughts
The PSTN switch off is a clear signal for businesses to move toward modern, internet-based communication systems. Making the shift early allows proper planning, smoother implementation, and access to better features that support growth and flexibility. Waiting until the deadline only creates unnecessary pressure and limits your options. A well-planned transition ensures your business stays connected, efficient, and ready for the future.
