The UK PSTN switch-off what every business needs to know.
By 2027 the traditional copper phone network will be switched off. This guide explains what that means, how it affects your business, and the simplest way to move to a modern VoIP phone system.
PSTN is the old copper telephone network that has carried UK calls for over a century.
PSTN stands for Public Switched Telephone Network. It is the analogue network of copper wires, green street cabinets and traditional exchange equipment that has connected homes and businesses to the phone network since the late 1800s. If you still have a standard landline, an ISDN line, or a fax machine plugged into a wall socket, it is almost certainly using PSTN.
In 2027 BT Openreach will stop running this network. Every phone line that relies on it will have to move to a digital, internet-based service.
Common PSTN services being retired
- Analogue business phone lines
- ISDN2 and ISDN30 lines
- PSTN-based broadband (ADSL, FTTC)
- Fax machines using traditional lines
- Lift emergency lines and alarm lines
- Payphones and some card payment terminals
The copper network is too old and too expensive to maintain.
End of an ageing system
Much of the PSTN infrastructure is decades old. Replacement parts are becoming harder to source, the skills needed to maintain the equipment are retiring out of the workforce, and running two parallel networks is inefficient.
Digital is the future
Internet-based calls and services can carry voice, video and data together, are easier to manage, and allow faster fault resolution. The PSTN switch-off is the final step in a nationwide move to digital communications.
When does the PSTN switch-off happen?
No new PSTN connections
Openreach stopped selling new PSTN-based phone lines and ISDN services in many areas.
Stop-sell for copper products
Businesses can no longer order new PSTN-related products or significant changes to existing ones.
PSTN switch-off
The copper network is fully retired. All voice and data services must run over IP.
The official switch-off date is 31 January 2027.
Leave the migration too late and you risk losing service, missing the best supplier pricing, and scrambling to replace equipment that should have been retired years ago.
Anything that still uses copper phone lines will be affected.
Your phone lines stop working
Any device that still relies on a copper phone line will go dead after the switch-off.
Broadband may need replacing
ADSL and FTTC broadband that runs over PSTN will also need a digital replacement such as FTTP or SOGEA.
Services need planning now
Alarms, lifts, payment terminals and emergency phones may need specialist IP converters or replacements.
Phone numbers need migration
You can keep your existing business numbers, but only if they are properly ported to a VoIP platform.
A practical checklist for small businesses.
- 1Audit every phone line, broadband circuit and connected device on your premises.
- 2Identify which services are PSTN-based, including ISDN, fax, alarms, lifts and payment terminals.
- 3Check your internet connection. VoIP needs a stable, adequate broadband connection.
- 4Choose a VoIP platform or supplier that fits how your team works.
- 5Plan your number porting and any new handsets, headsets or softphone apps.
- 6Run a staged migration so disruption is kept to a minimum.
- 7Test everything thoroughly before the PSTN switch-off date.
Do not wait for the deadline
The businesses that fare best are the ones that start early. A rushed migration usually means paying more, accepting worse terms, and forcing your team to learn new tools under pressure.
Starting now gives you time to compare suppliers, test call quality, train staff, and fix any network issues before your old lines are cut off.
VoIP is the replacement for PSTN phone lines.
Voice over Internet Protocol (VoIP) carries your phone calls over the internet instead of copper wires. It is the standard replacement for PSTN and is already used by most modern business phone systems.
What VoIP gives your business
- Keep your existing business phone numbers
- Make and take calls from mobiles, laptops and desk phones
- Lower line rental and free internal calls between sites
- Add features like call queues, recording and auto attendants
- Scale up or down as your team changes
- Work from anywhere with the same business number
What internet speed do you need?
A typical VoIP call needs roughly 100 kbps per call. A small office with five people on the phone at once will usually be fine on a standard fibre connection, but we always recommend a quick bandwidth check before ordering.
Do you need new phones?
Not always. Many VoIP systems work through apps on computers and mobiles. If you like desk handsets, most modern VoIP handsets are affordable and plug straight into your network. We can reuse existing cabling where it makes sense.
Common questions about the PSTN switch-off.
What exactly is being switched off in 2027?
The Public Switched Telephone Network (PSTN), which is the old copper-based telephone network. This includes traditional analogue phone lines, ISDN lines and many services that rely on them such as ADSL broadband, FTTC broadband, fax lines and some alarm and lift lines.
Will my business phone numbers still work?
Yes, if you move them to a VoIP service and port them correctly. Number porting is a standard process, but it needs to be planned properly so you do not lose inbound calls during the migration.
Can I just keep my existing handsets?
Old PSTN handsets will not work on a digital line without an adapter, and even then they miss most of the useful features of VoIP. Most businesses choose modern VoIP handsets or softphone apps instead.
What happens if I do nothing before 2027?
Your phone lines will simply stop working. You may also lose broadband, alarm monitoring, lift emergency lines or card payment services that depend on the copper network. Your supplier may move you automatically, but on their terms and timeline, not yours.
Is VoIP reliable enough for business use?
Yes. VoIP is the standard for business telephony today and is already used by millions of UK companies. Reliability depends on your internet connection and network setup, which is why we review both before recommending a platform.
How much does it cost to move to VoIP?
Costs vary depending on the number of users, chosen platform, handsets and any broadband upgrades. In many cases, ongoing costs are lower than ISDN because line rental and call charges are reduced. We provide clear quotes with no hidden fees.
Need help moving your business phones before 2027?
Book a free consultation and we'll audit your current lines, recommend the right VoIP setup, and plan a smooth migration with no downtime.