PSTN Switch-Off 2027: The UK Small Business Guide

If your business still has a traditional phone line, you have a hard deadline: 31 January 2027. On that date the UK's analogue phone network is switched off for good, and any service still running on it stops working.

This guide is for UK small businesses, sole traders, and tradespeople who have a landline, an ISDN system, or a card machine that dials out — and who want to know exactly what to do about it. It covers what the switch-off is, what breaks, what it costs to wait, and the three realistic ways to replace your line.

What is the PSTN switch-off?

The PSTN (Public Switched Telephone Network) is the copper-wire analogue phone network that has carried UK voice calls since the 1800s. The PSTN switch-off is the retirement of that network in favour of digital, internet-based calling — known as all-IP or VoIP (Voice over Internet Protocol).

Openreach, which owns and maintains the physical network, is switching off both the PSTN and ISDN (the digital multi-line version used by older office phone systems). From the switch-off date, all UK voice calls run over an internet connection instead.

You may also see it called the big switch off, the digital switchover, or the analogue phone switch off. These all describe the same programme.

Why is it happening?

The copper network is decades past its design life. It is expensive to maintain, parts are increasingly hard to source, and it cannot deliver the speeds or reliability that modern businesses need. Rather than keep patching it, BT Group is retiring it entirely and moving everyone to fibre and IP-based services.

This is not optional and it is not a sales tactic. It is a national infrastructure change, tracked by the House of Commons Library and regulated by Ofcom.

When is the PSTN switch off?

The PSTN switch-off completes on 31 January 2027.

The deadline moved once already. The original target was the end of December 2025, but the programme was extended to give providers time to resolve safety issues — particularly for telecare users who rely on alarm pendants. Those issues have now been resolved.

How much time is actually left?

From September 2026, you have roughly five months. That sounds like plenty until you account for the queue.

As of 31 July 2026, around 1.5 million lines were still running on the legacy copper network, and roughly 350,000 of those served business premises. Every one of those needs migrating before the deadline, by a finite number of engineers and providers. The closer you get to January, the longer the lead times.

Who does the switch-off affect?

You are affected if any of the following is true:

• You have a landline at your business premises (an 01 or 02 number on a copper line)
• You use an ISDN phone system — common in offices with several extensions
• You have a card payment terminal that dials out over the phone line
• You have a lift alarm, intruder alarm, fire alarm, or CCTV that reports over a phone line
• You have a door entry system connected to a phone line
• You rely on a fax machine, franking machine, or a telecare pendant

You are not directly affected if your business runs entirely on mobiles, or if you already use a VoIP or app-based phone service. Mobile networks are separate and are unaffected by the PSTN switch-off.

What actually stops working

This is the part small businesses most often underestimate. The phone line is rarely just a phone.

The alarm and lift cases matter most. A non-functioning lift alarm is not just an inconvenience — it is a safety and compliance problem. These need booking with your maintenance provider well ahead of the deadline.

The cost of waiting

Delay is not free. Openreach has been steadily raising the price of legacy line rental (WLR) to encourage migration, and the increases in 2026 were steep:

• 1 April 2026 — basic line rental rose by 20%
• 1 July 2026 — a further 40% increase
• 1 October 2026 — another 40% increase

The combined effect is that legacy line rental has roughly doubled over 2026. Every month you stay on the old network, you pay a premium for a service that is being switched off anyway. Most digital alternatives cost less than the line rental you are currently paying — so migrating early usually saves money rather than costing it.

There is a second cost too. Missed calls have a measurable price: our analysis of the hidden cost of missed calls for UK small businesses found the average firm loses a significant sum each year to calls that never get answered. A rushed, last-minute migration in January is exactly how you end up with downtime and missed calls.

Your three options

There is no single right answer. It depends on what your phone line actually does for you.

Option 1 — A like-for-like digital landline

Your provider replaces your analogue line with a digital equivalent (often branded "Digital Voice" or similar). You keep a desk phone; it plugs into your router rather than the wall socket.

Good if: you genuinely need a desk phone at a fixed premises, or you have a reception setup that staff are used to.

Watch out for: it needs a working broadband connection and mains power. In a power cut, a digital landline stops unless you have a battery backup unit. Ofcom requires providers to offer at least one hour of battery backup for customers who need it, and many go beyond that — but it is something you must ask for.

Option 2 — A full VoIP phone system

A hosted phone system with IP handsets, extensions, call queues, and an admin console.

Good if: you have an office with several staff, need call queues and extensions, and have someone who can manage it.

Watch out for: cost and complexity. You are typically looking at £10–£20 per user per month plus handsets. For a two-person business this is usually more system than you need.

Option 3 — A mobile business number app

Instead of replacing a landline with another landline, you replace it with a dedicated business number that lives on the phone you already carry. Calls, texts, and WhatsApp arrive in one app, shared across your team.

Good if: you are a sole trader, a trade, or a small team who are out of the office more than in it — which describes most UK small businesses affected by the switch-off.

Watch out for: if you specifically need a geographic 01/02 area code for local credibility, check availability with your provider before committing.

Comparing the three

That power-cut row is worth pausing on. A digital landline and a hosted VoIP system both depend on your broadband and mains power. A number that runs on your mobile does not.

How to prepare: a 6-step plan

Can I keep my phone number?

Yes — in almost all cases. UK number portability rules mean your number belongs to you, not your provider. You can move it to a digital service rather than losing it.

Three practical points:

1. Start early. Two to four weeks is typical for a business port, and the queue grows as January approaches.
2. Do not cancel your old line first. Cancelling releases the number and you may lose it permanently. Port first, cancel after.
3. Check the number type. Geographic 01/02 numbers and mobile 07 numbers port under different processes. Confirm with your new provider before you commit.

If your existing number is not worth keeping — for example, it is a number customers rarely use, or it is tied to premises you are leaving — the switch-off is a clean opportunity to move to a number that does more. A mobile business number can receive SMS and WhatsApp as well as calls, which no landline number can do.

Three mistakes to avoid

Leaving it until January. Engineer availability, porting queues, and provider support all get worse as the deadline approaches. A migration that takes two weeks in September can take two months in December.

Only thinking about the phone. The phone is usually the easiest part. The card terminal, the lift alarm, and the intruder alarm are where businesses get caught out — and those are the ones with real consequences.

Replacing like for like without thinking. The switch-off forces a decision you would otherwise have put off for years. Buying a digital replica of a phone system you already found frustrating is a wasted opportunity. Look at what a modern business phone line actually costs before you sign a three-year contract.

Where Line fits

Line is a UK business phone number that runs on the phone you already have. There is no line to install, no handset to buy, and nothing that stops working in a power cut.

For a business facing the switch-off, that means:

• A dedicated UK business number — calls and texts, separate from your personal number
• A shared inbox so calls, SMS, and WhatsApp land in one place for your whole team
• Rings on every device at once — no forwarding codes, no per-minute diversion charges
• Number porting supported if you want to bring your existing number across
• No hardware and no engineer visit — you are set up in minutes, not weeks

It is not the right answer for everyone. If you need a reception desk with twelve extensions and call queues, buy a proper VoIP system. But if your landline was mainly a number that customers rang and you forwarded to your mobile, Line replaces it directly — and does more than the line ever did.

You can see current pricing or read how Line compares to a traditional virtual landline.

Wrapping up

The PSTN switch-off is a fixed deadline: 31 January 2027, with no further extension. Around 350,000 business premises were still to migrate as of mid-2026, and legacy line rental doubled during 2026 to push people to move.

The three things to do now:

1. List everything on your phone line — not just the phone. Alarms and card terminals are the real risk.
2. Book alarms and lifts first. They have the longest lead times and the highest consequences.
3. Choose deliberately. A landline replacement is one option, not the only one. For most small businesses a business number on your mobile does more for less.

The businesses that handle this well treat it as an upgrade rather than a chore. The line was going away regardless — the only real decision is what you replace it with, and whether you make that decision in September or in a panic in January.