The PSTN switch-off explained.
What the 2027 PSTN and ISDN switch-off means for your business — and the simple steps to be ready.
What is the PSTN switch-off?
The PSTN (Public Switched Telephone Network) is the traditional copper-based phone network the UK has used for over a century. Openreach is retiring it, along with ISDN, by the end of January 2027. After that date, these analogue and digital lines will stop working and everything moves to internet-based (IP) calling.
It’s one of the biggest changes in UK telecoms history, and it affects far more than just phones.
Who and what is affected?
Any business still using analogue lines, ISDN, or an older on-premise phone system is affected. But it goes beyond phone systems: anything that quietly relies on a phone line is in scope — alarm and CCTV lines, door entry systems, lift emergency phones, card payment terminals, fax machines and some EPOS systems.
If you’re not sure what in your business depends on a traditional line, that audit is the first thing to do — and something we can help with.
Key dates
The headline date is the end of January 2027, when the PSTN and ISDN are switched off nationally. In many areas, providers already stopped selling new analogue and ISDN lines, and some exchanges are being migrated earlier. The safe approach is to plan your move now rather than wait for the deadline.
How to prepare
The fix is to move to internet-based calling — a hosted VoIP or cloud phone system — and to make sure any line-dependent equipment (alarms, lifts, door entry) is moved to a compliant alternative. We port your existing numbers so nothing changes for your customers.
Done properly, the switch is straightforward and usually cuts your bill. The businesses that struggle are the ones that leave it to the last minute.
Why this is good news
Although it’s a forced change, moving off the PSTN is a genuine upgrade: lower call costs, mobile and remote working, modern features like call recording and AI handling, and a system that scales with you. The switch-off simply brings forward a move most businesses would benefit from anyway.
Frequently asked questions
When is the PSTN switch-off?
By the end of January 2027, when the traditional PSTN and ISDN network is retired nationally.
What happens if I do nothing?
Your phones — and potentially alarms, lifts and card machines on old lines — will stop working. Moving in advance avoids that.
Will I lose my number?
No — we port your existing numbers to the new system.
Is moving expensive?
Usually it lowers your costs — cloud systems start from around £5 per user with no big upfront spend.
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