It's one of the biggest changes to UK business communications in decades, and many businesses still haven't heard about it: the PSTN and ISDN switch-off. If your business still uses traditional phone lines, this affects you directly.
What is being switched off?
- The PSTN (Public Switched Telephone Network) is the traditional analogue phone network - the copper lines that have carried calls for over a century.
- ISDN is the older digital system many businesses use for multiple lines and phone systems.
Openreach is retiring both. By the end of January 2027, these networks will be switched off across the UK and replaced with digital, internet-based alternatives.
Why is this happening?
The copper network is old, increasingly expensive to maintain, and simply wasn't built for the modern world. The future is digital - voice carried over the internet using VoIP, the same technology powering hosted telephony.
What does it mean for your business?
If you rely on traditional lines, you'll need to move to a digital phone system before the switch-off. But it's not only phones - anything that uses a phone line may be affected, including:
- Phone systems and ISDN-based PBXs
- Card payment terminals
- Alarm systems and CCTV
- Door entry systems
- Lift emergency lines
It's worth auditing everything connected to a phone line, not just the handsets.
Is this a problem or an opportunity?
Genuinely, it's an opportunity. Moving to hosted telephony isn't just replacing like for like - you gain lower costs, work-from-anywhere flexibility, and a suite of modern features the old network could never offer. Businesses that have already switched rarely look back.
How to prepare
- Audit every device and service using a phone line.
- Check your internet is up to carrying calls - see internet speed for VoIP.
- Choose a hosted system that fits your needs.
- Keep your numbers - they port across to the new system, as we explain in number porting.
- Switch early - don't wait for the deadline rush.
The bottom line
The switch-off is happening, and the deadline is closer than it feels. Businesses that move early do so calmly, on their own terms, and start enjoying the benefits sooner. Leave it late and you risk a scramble. Want a stress-free switch? Explore our Cloud Telephony service or request a callback.
Frequently asked questions
What is the PSTN/ISDN switch-off?
The UK's traditional analogue phone network (PSTN and ISDN) is being retired, with services ending by early 2027. After that, phone services must run over digital, internet-based connections.
What do I need to do before the switch-off?
Move your phone system to a digital alternative such as hosted telephony, and make sure any devices that rely on phone lines, like alarms and lifts, are migrated too.
What happens if I do nothing before 2027?
Affected analogue lines and the services on them will simply stop working, so it is important to plan your move well ahead of the deadline.
