All ISDN and PSTN services in the UK will be permanently switched off on 31 January 2027. An estimated six million businesses still rely on these legacy connections for phone systems, broadband or connected devices, and many have not started planning their migration. No new ISDN lines have been available since September 2023, Openreach is withdrawing remaining services region by region through 2026, and there will be no further extension.
The replacement technology, VoIP and IP-based connectivity, is already well established and brings genuine improvements in flexibility, cost and reliability. But the transition is not as simple as swapping a handset. Businesses that only think about their phone system risk overlooking the alarms, payment terminals, lift phones and monitoring equipment that also depend on copper lines.
At The Unite Group, we handle ISDN-to-IP migrations for businesses across the North East and beyond, covering phones, broadband and every connected device in between. This checklist is designed to help you audit your premises and identify everything that needs to move before the deadline.
Your Room-by-Room Migration Checklist
Walk through your premises and check every device that connects to a phone socket or ISDN line. Here is what to look for.
Phone system
If you are running a traditional PBX connected to ISDN30 or ISDN2 lines, it will stop working entirely. You need to move to a cloud-hosted phone system or, if your existing PBX supports it, add a SIP gateway to route calls over your broadband instead. Your existing phone numbers can be ported to the new system.
Broadband
If your internet connection runs over an ADSL line or FTTC broadband that depends on an active phone line, you will need to switch to SoGEA or FTTP (full fibre) where available. Check with your provider which options are available at your premises.
Intruder alarm
Many alarm systems use a phone line to call the monitoring centre when triggered. After the switch-off, that connection will not work. Contact your alarm provider to check whether your system is IP-compatible or needs replacing with one that communicates over broadband or 4G.
Fire alarm
Fire panel communicators that dial out over PSTN will fail. These need upgrading to IP-based or cellular communicators. Given the safety implications, this should be a priority rather than something left until the final months.
Lift emergency phone
Building regulations require lifts to have a working emergency phone. Most use an analogue phone line. After the switch-off, these need replacing with IP or GSM-based lift communicators. Speak to your lift maintenance provider about compatible options.
Card payment terminals
Older EPOS and card terminals that dial out over a phone line will stop processing payments. Most modern terminals use broadband or 4G connectivity, but if your terminal still has a phone cable connected, it needs replacing or upgrading.
Fax machine
If your business still uses fax (some legal and healthcare businesses do), physical fax machines connected to a phone line will stop working. Online fax services that send and receive via email are the practical replacement.
Door entry and intercom systems
Some door entry systems use phone lines to call internal extensions or mobile numbers. These need checking for IP compatibility.
Building management systems (BMS)
HVAC monitoring, water treatment controls and similar systems sometimes phone home using analogue lines. Check with your building management provider.
CCTV and remote monitoring
Older CCTV systems that transmit footage via phone lines need upgrading to IP-based cameras and network video recorders.
Telecare and health monitoring devices
Pendant alarms and health monitoring equipment that use phone lines require urgent attention. BT has paused forced migrations for vulnerable customers, but replacement devices still need to be in place before the deadline.
When to Start (and When It Gets Difficult)
Migration is not something you can do in a week. A typical business needs to audit what it has, choose replacement solutions, order equipment, schedule installations and test everything. For most SMEs, the whole process takes two to four months when planned properly.
As January 2027 approaches, demand for engineers, equipment and installation slots will spike. Businesses that leave it until the final quarter of 2026 risk delays, limited availability, and higher costs from providers under pressure to deliver.
The sensible window for migration is now through the end of 2026. Starting earlier gives you time to test, resolve issues, and avoid the inevitable last-minute scramble.
What Happens If You Miss the Deadline
On 1 February 2027, every service still connected to the old copper phone network stops working. Phone lines go silent. Alarm systems lose their connection to monitoring centres. Card terminals stop processing payments. Broadband connections that depend on a phone line drop offline.
There will be no extension. The infrastructure is being physically retired because it is too old and expensive to maintain. Ofcom reported a 45% increase in PSTN resilience incidents in 2024, underlining why the network is being replaced.
Get a Free Migration Audit
If you are not sure which devices in your business still rely on ISDN or PSTN, that is the first thing to find out. Contact The Unite Group for a free migration audit. We will walk through your setup, identify every affected device and service, and give you a clear plan for migrating everything before the deadline, including your phone system, broadband and connected equipment.