The UK PSTN Switch-Off Explained for Small Businesses

On 31 January 2027, the UK’s traditional copper telephone network — the PSTN — will be permanently switched off. Every landline, fax machine, alarm line, and ISDN connection that relies on it must move to a digital service. With the deadline now only weeks away, Openreach figures reported in October 2026 show that around 1 million lines are still on the old copper network — including roughly 300,000 business premises^[1]. If your business still uses a traditional phone line, the time to act is now.

This guide explains exactly what the PSTN switch-off means for small businesses, what will stop working, what happens if you miss the deadline, and how to move your phone number to a digital service quickly — even at this late stage.

What Is the PSTN?

The PSTN — Public Switched Telephone Network — is the traditional copper wire telephone system that has carried UK landline calls for decades. When you think of a “normal” phone line — the kind with a physical socket in the wall, a dial tone, and a phone plugged into it — that’s the PSTN.

Built originally for voice calls, the PSTN also underpins a vast range of other services that businesses rely on daily: fax machines, card payment terminals, burglar alarms, door entry systems, lift emergency phones, and older broadband connections (ADSL). It’s the invisible infrastructure behind millions of UK businesses.

ISDN lines — both ISDN2e and ISDN30 — also run over this copper network. If your business uses ISDN for phone systems, conferencing, or data, those lines are switching off too.

Why Is It Being Switched Off?

The copper network is old. Much of it dates back to the mid-20th century, and maintaining it has become increasingly expensive and impractical. The technology is outdated, spare parts are harder to source, and the engineers who specialise in it are retiring.

BT Openreach — the company responsible for the UK’s telephone infrastructure — has decided that continuing to prop up a legacy network alongside modern fibre and digital systems is no longer sustainable. The future is Internet Protocol (IP) — where voice calls travel over broadband connections rather than dedicated copper wires.

This isn’t unique to the UK. Telecoms operators across Europe and around the world are retiring their analogue networks in favour of all-IP services, for the same reasons: lower running costs, better reliability, and the ability to offer modern features.

The Timeline: What’s Happening and When

The PSTN switch-off was originally planned for December 2025 but was pushed back to give households and businesses more time to prepare. The final deadline is 31 January 2027, and Openreach has been clear that “there is no extension to the deadline”^[3].

Throughout 2026, Openreach deliberately made legacy lines more expensive to encourage businesses to move. If you’re still on a traditional line, you’re already paying for all three of these rises:

What Stops Working on Switch-Off Day?

The PSTN switch-off doesn’t just affect the phone on your desk. Any equipment or service that connects through a traditional phone line will be impacted. For many businesses, the phone itself is only the tip of the iceberg.

The scale of the problem is significant. Openreach data from February 2026 showed more than 12,000 lift emergency phone lines and around 500 lines serving CCTV networks still needed upgrading^[4]. Openreach also offers free equipment testing at its test labs if you’re unsure whether a device will work on a digital line.

Who Is Affected?

If your business has a traditional landline — the kind with a physical BT-style socket and a dial tone — you are affected. If you have ISDN lines for a phone system, you are affected. If your broadband is ADSL (delivered through a phone line), you are affected.

No region is exempt. According to the latest Openreach figures reported by ISPreview, the areas with the most lines still to switch are London and the South East (over 250,000), Wales and the Midlands (over 233,000), and Northern England (over 207,000), with significant numbers remaining in Wessex, Scotland, East Anglia, and Northern Ireland^[1].

Small businesses are disproportionately affected because they’re less likely to have dedicated IT support, less likely to have been contacted by their provider about migration, and more likely to be relying on older equipment that hasn’t been updated in years.

What Happens to My Phone Number?

This is one of the biggest concerns small businesses have — and the good news is straightforward. You can keep your existing phone number. The switch-off retires the copper network, not the numbers that run on it.

Through a process called number porting, your existing landline number can be transferred to a VoIP provider, a hosted phone system, or a virtual phone number service. The number stays the same — your customers, your website, your business cards, your Google listing — nothing changes from their perspective. The only difference is that calls are carried over the internet rather than copper wires.

Number porting typically takes 5–10 working days, though it can vary depending on the losing provider. The key is to start the process well before the deadline, not in the final weeks when porting teams will be swamped with last-minute requests.

Your Options After the PSTN

You have several choices for replacing your traditional phone line. The right one depends on the size of your business, your budget, and how you use your phone. Here’s how the main options compare:

For most small businesses — tradespeople, freelancers, sole traders, small shops, and service companies — a virtual phone number is the simplest, most affordable, and most flexible replacement. It requires no new hardware, no broadband dependency for receiving calls, and can be set up in minutes.

For a deeper look at what happens to your phone service after the switch-off, read our guide on what happens to business phone lines after 2027.

Why Virtual Numbers Are the Smart Choice for Small Businesses

A virtual phone number is a phone number that isn’t tied to a physical line or location. Calls to your virtual number are routed over the internet and forwarded to any phone you choose — your mobile, a colleague’s phone, or multiple phones simultaneously. It’s the modern replacement for a traditional landline, without the copper wire.

For small businesses facing the PSTN switch-off, virtual numbers solve the problem completely:

• No copper dependency Virtual numbers don’t use the PSTN at all. They’re already digital, so the switch-off doesn’t affect them. This is a future-proof solution, not a temporary fix.
• Keep your existing number Port your current landline number to a virtual service and your customers won’t notice any change. Same number, better features.
• Intelligent call forwarding Forward calls to your mobile, a landline, or multiple phones. If you don’t answer, calls go to cloud voicemail and are emailed to you as audio files.
• Time-of-day routing Route calls differently depending on the time of day or day of the week. Business hours ring your phone; evenings go to voicemail with a professional greeting.
• Call recording Record calls for training, compliance, or dispute resolution — something a traditional landline couldn’t do without expensive add-on equipment.
• Full online control Manage everything through the Virtually Local online portal. Change forwarding destinations, update greetings, view call history — all from your phone or computer.

Unlike a hosted phone system that requires broadband and IP handsets, a virtual number works with the phone you already have. There’s nothing to install, no hardware to buy, and no IT expertise needed. For the full list of what’s included, visit our features page.

Getting Started: How to Switch Before the Deadline

Whether you’re replacing a traditional landline or setting up a new number from scratch, the process with Virtually Local takes minutes — not weeks.

Short on time? Our PSTN switch-off checklist for the final 12 weeks breaks the whole job into weekly tasks. For a step-by-step walkthrough of replacing your landline before the copper network closes, see our detailed guide: How to Replace Your Business Landline Before the Copper Network Closes.

What If You Miss the Deadline?

Openreach has said that lines still on the old network won’t simply go dead overnight on 31 January 2027. Instead, from that date, customers who haven’t moved to a digital service may be transferred to EVAc (Emergency Voice Access) — which Openreach describes as “a limited last-resort phone service designed to maintain access to essential calls”^[2].

EVAc is not a plan you should rely on:

• It’s temporary. Openreach calls it “a final safety net while providers complete customer migrations” — you will still have to move to a digital service^[2].
• It’s limited. Capacity is not unlimited and cannot be reserved, and Openreach warns it may not support the calling features you use today^[2][6].
• It’s expensive. Openreach charges providers £35 a month for a basic line on EVAc, before any retail mark-up^[2] — several times the cost of a virtual number.

For a business, losing features like caller display, call forwarding, or voicemail even temporarily means missed enquiries and lost revenue. Moving your number to a digital service now avoids all of this.

The Bottom Line

The PSTN switch-off is not a future possibility — it’s a confirmed event with a fixed date. On 31 January 2027, the UK’s copper telephone network will be retired. Every traditional landline, ISDN connection, and copper-dependent device needs a digital replacement, and the temporary EVAc fallback is limited, costly, and not a long-term option. Openreach has stated clearly that there will be no further extensions.

For small businesses, the practical impact is significant but entirely manageable — provided you act in good time. Your phone number can be kept. Your calls can be handled better than ever. And the cost of a modern replacement is almost certainly less than what you’re paying for your legacy line, especially now that the 2026 price increases have taken effect.

The businesses that migrate early will benefit from lower costs, better features, and a smoother transition. The businesses that wait will face rising bills, limited support, and the real risk of losing their phone service at the worst possible moment.