ISDN and PSTN switch off January 2027
The old copper phone network that has served UK businesses for decades is being retired. Every business still using traditional phone lines needs to move to a modern digital system — or risk being disconnected.
PSTN (Public Switched Telephone Network) and ISDN(Integrated Services Digital Network) are the traditional copper-wire phone networks that have been connecting phone calls in the UK for decades. They're the reason your office phone can make a call, your fax machine works, and your burglar alarm can phone home.
In 2017, BT announced it would be switching off the entire PSTN and ISDN network by 2025. That deadline was later extended to January 2027. After that date, these networks simply won't exist anymore. It's not a threat — it's a technical sunset. The copper cables are ageing, hard to maintain, and can't deliver the speeds or features that modern businesses need.
Every phone call, broadband connection, and service that relies on this network must move to modern alternatives — mostly VoIP (Voice over IP) and fibre-based services. Think of it like the switch from analogue TV to digital: once the switch happens, the old equipment just stops working.
If your business uses traditional phone lines — whether that's a desk phone, a fax machine, a card payment terminal, a burglar alarm, or a lift emergency phone — it could be connected to the PSTN or ISDN network. When the switch-off happens, anything still using those old connections will stop working.
Important:You can't just ignore this and hope it goes away. After January 2027, there will be no PSTN or ISDN service to connect to. No backup. No extension. Every business must migrate.
Here's what's at stake:
The process is straightforward, especially when you have the right partner. Here are the three main steps:
Identify every phone line, service, and device in your business that relies on the old network. This includes desk phones, fax machines, alarms, payment terminals, and lift phones. You might be surprised how many things plug into a phone line.
For voice calls, the standard replacement is VoIP (Voice over IP) — a digital phone system that runs over your internet connection. You can keep your existing phone numbers, get more features, and often pay less than you do now. Other services (alarms, payment terminals) may need different digital alternatives.
This is not a DIY project for most businesses. A good telecoms partner will handle the audit, recommend the right system, port your phone numbers, install and configure everything, and make sure your alarms and other services are migrated too. You don't need to become a technical expert — you just need the right support.
We've been migrating businesses off ISDN and PSTN for years. We know exactly what's involved — and we handle the whole process so you don't have to.
We review your current setup and identify every service, line, and device that needs migrating. No commitment, no hard sell.
Cloud hosted voice, SIP trunks, or a hybrid setup — we'll recommend the best modern solution for your size, budget, and needs.
Our engineers handle the full install, number porting, and configuration. Your new system will be up and running before the old one is switched off.
We don't disappear after the install. You get ongoing UK-based support from engineers who know your setup inside and out.
The switch-off is already underway. Here are the key dates to be aware of:
BT and other providers stopped selling new ISDN and PSTN lines. You can no longer order new traditional phone lines.
The busiest period. Businesses that wait will find engineers and installers in high demand. Prices may rise as capacity tightens.
The PSTN and ISDN networks are switched off permanently. Any service still using these lines will cease to work.
Don't wait until 2026. The closer we get to the deadline, the more businesses will be scrambling for engineering appointments, number ports, and installations. Act now and you'll have a smooth, stress-free migration at a better price.
Common questions about the switch-off, answered simply.
Get a free, no-obligation audit of your current setup. We'll tell you exactly what needs to change, how much it will cost, and how we can help you make a smooth transition before the January 2027 deadline.