PSTN Switch-Off 2027: What to Do Now

The UK's old analogue phone network, the PSTN, and ISDN lines are being permanently switched off on 31 January 2027. The date was originally December 2025 and was pushed back, but in July 2026 Openreach confirmed there will be no further extension. After the PSTN switch-off, any service still relying on a traditional copper phone line will stop working.

For most businesses the switch-off is straightforward to prepare for, but only if you start early. This guide covers what is affected, a step-by-step plan, the mistakes to avoid and the questions to ask your suppliers.

What is the PSTN switch-off?

The Public Switched Telephone Network (PSTN) has carried UK phone calls over copper wires for decades. ISDN is the digital service many businesses used for multi-line phone systems. Both are being retired, and calls will run over internet connections instead.

New traditional lines, known as Wholesale Line Rental, have not been sold since 5 September 2023. Any you still have are on borrowed time, so the question is not whether to move but when.

What stops working after the PSTN switch-off?

Your desk phones are the obvious one, but plenty of other equipment quietly relies on a phone line:

Phone systems using analogue or ISDN lines
Alarm systems, including monitored fire and intruder alarms that signal to a monitoring centre
Lift emergency phones and door entry systems
Card payment terminals that dial out over a phone line
Fax machines and franking machines
Broadband that depends on a phone line, such as standard ADSL or FTTC with line rental

The hidden risk is equipment nobody thinks of as a phone. An alarm panel or lift phone can sit on a line for years without anyone checking it, and you may only find out it has stopped working when you need it.

What it looks like for a typical office

Imagine a hypothetical ten-person office on a business park. It has an ageing phone system on ISDN, a monitored intruder alarm, a franking machine and FTTC broadband bundled with a phone line. Nobody has looked closely at the line bills in years.

On paper, only the phone system looks like a problem. In reality, the alarm, the franking machine and the broadband all depend on the old lines too, and each has a different supplier to talk to.

Handled early, that office can move to VoIP, switch to broadband that does not need a phone line and get each supplier to confirm their equipment is ready, in a planned order. Left until January, it becomes several urgent jobs at once.

Seven steps to prepare for the switch-off

Audit every line. List each phone number and line you pay for, and find out what is plugged into it. Older bills, the master socket and the comms cabinet are good places to start.
Plan your phone system. Moving to a VoIP phone system means calls run over your internet connection. You can usually keep your existing numbers, and many systems let calls reach staff on mobiles or laptops too.
Check your broadband. Your connection needs to work without a phone line, such as SoGEA or full fibre (FTTP). Our business broadband options and FTTC, FTTP and 4G/5G connections cover this.
Contact your equipment suppliers. Ask your alarm, lift, door entry and card terminal providers how their equipment will work after the switch-off, and when they will update it.
Check your office network. VoIP handsets plug into your network, so switches, cabling and Wi-Fi need to be up to the job. Our network equipment and structured cabling services can fill any gaps.
Plan for outages. Once your phones run over the internet, a broadband fault or power cut affects calls too. A backup internet connection and battery backup for key equipment keep you reachable.
Test before you cancel. Only cease the old lines once everything has moved and been tested, including alarms and emergency phones.

Common mistakes to avoid

Assuming your phone provider will sort everything. They may not know what else is plugged into your lines.
Forgetting non-phone equipment such as alarms, lift phones and franking machines.
Cancelling lines too early, before every device on them has been moved.
Ignoring power cuts. Unlike old copper phones, VoIP handsets and routers need mains power.
Overlooking your internet connection. Calls share it with everything else, so a connection that already struggles at busy times needs looking at first.

Questions to ask your suppliers

Phone provider: Can we port all of our numbers, and what happens to calls if our internet goes down?
Broadband provider: Does our connection depend on a phone line, and is SoGEA or full fibre available at our address?
Alarm company: Will our alarm signalling work after 31 January 2027, and when will it be upgraded?
Lift and door entry suppliers: What replaces the phone line for emergency calls?
Card terminal provider: Does our terminal dial out over a phone line, and can it use broadband or mobile data instead?

A suggested timeline

Now: audit your lines, contact suppliers and order replacement broadband if you need it. Number porting and new connections are not instant, so build in time.
Before Christmas: move your phones to VoIP and switch over your broadband, then test calls, alarms and card payments.
Early January 2027: finish any remaining moves, confirm every device works without the old lines, then cancel them.
31 January 2027: remaining traditional lines are switched off.

Don't leave it until January

Every business in the country faces the same deadline, so engineers and equipment will get busier as it approaches. Planning now lets you move on your own timetable, test everything properly and avoid a rushed changeover.

How we help

We help businesses across Stoke-on-Trent and Staffordshire plan and complete the move, from auditing lines to installing VoIP, broadband and backup connections. Once you are switched over, our business broadband support is on hand if anything goes wrong.

A new router is also a good moment to check your security settings, and our routers and firewalls service covers that. If the phones are only one of several things creaking, our guide to 10 signs your business has outgrown its IT setup is worth a read.

Frequently asked questions

When is the PSTN switch-off?

The national PSTN and ISDN switch-off date is 31 January 2027. It was originally planned for December 2025 and was extended, but Openreach confirmed in July 2026 that there will be no further extension. New traditional phone lines have not been sold since 5 September 2023, so businesses should plan their move now.

Can we keep our phone numbers?

In most cases, yes. Existing numbers can usually be moved, or ported, to a VoIP phone system, so customers and suppliers can still reach you on the numbers they know. Confirm every number you want to keep before cancelling anything, including secondary and fax lines that may only appear on older bills.

What happens to our phones in a power cut?

VoIP phones need power and a working internet connection, so a power cut or broadband fault can stop calls. Battery backup for your router, network switch and key handsets keeps essential phones running, and a backup internet connection keeps calls flowing if your main line fails. Many VoIP systems can also send calls to mobiles.

Will our alarm system stop working after the switch-off?

It might, if it signals over a traditional phone line. Monitored fire and intruder alarms, lift emergency phones and door entry systems often use the old network without anyone realising. Contact your alarm or equipment supplier now, ask whether your system will work after 31 January 2027, and agree a date for any upgrade.

Do we need new broadband for the switch-off?

You will if your current broadband depends on a phone line, such as standard ADSL or FTTC with line rental. The replacement is a connection that works without one, such as SoGEA or full fibre (FTTP). Your broadband provider can confirm what you have now and what is available at your address.

Not sure what is still running on your old lines? Get in touch and our Stoke-on-Trent team will help you check and plan the move.

PSTN Switch-Off 2027: What UK Businesses Need to Do Now