Devices Affected by the PSTN Switch-Off: A Complete Checklist
The PSTN switch-off date is 31 January 2027. After that, Openreach shuts down the old copper telephone network for good. No extensions. No exceptions.
Most businesses know their desk phones will stop working. Far fewer know that burglar alarms, payment terminals, lifts, and medical pendants are in the same position. Some of these failures are inconvenient. Others are dangerous.
This checklist covers every device category you need to audit before the deadline. Work through it now. Do not leave this until 2026.
What Is the PSTN, and Why Does It Matter?
PSTN stands for Public Switched Telephone Network. It is the analogue copper wire network that has carried UK telephone calls since the Victorian era. BT's infrastructure arm, Openreach, is replacing it with an entirely digital, IP-based network.
Anything that uses a standard phone line — a BT line, a POTS line, an analogue connection — runs over PSTN. When the network closes, those connections die with it.
The Devices at Risk
1. Traditional Landline Phones
The obvious one. Any phone plugged into a standard BT wall socket will stop working.
Your options: switch to a VoIP phone service (which runs over your broadband connection), or use an analogue telephone adapter (ATA) to connect an existing handset to a VoIP service. An ATA is a small box that bridges the gap — useful if you have handsets you want to keep.
Moving your business phone system to VoIP now is the cleanest solution. It solves the landline problem entirely and usually cuts your phone bill at the same time.
2. ADSL Broadband
This one surprises people. ADSL broadband runs over the same copper telephone line as your voice calls. When PSTN goes, ADSL goes with it.
If your business broadband is ADSL — and many smaller businesses still use it — you need to upgrade. Your options are FTTC (fibre to the cabinet, the most widely available upgrade), FTTP (full fibre to the premises, the best option where available), or a 4G/5G fixed wireless connection if fibre is not accessible in your area.
Check your current contract now. Some ISPs will migrate you automatically; others will not.
3. Burglar Alarms and Intruder Alarms
Many commercial and domestic alarm systems use a PSTN dialler. When the alarm triggers, it calls the monitoring centre over the phone line. No phone line, no call. No call, no response.
The fix is either an IP communicator (which routes the alarm signal over broadband) or a GSM/4G communicator (which uses a mobile SIM). Both options exist and are widely fitted. Contact your alarm maintenance company and ask them specifically whether your system uses a PSTN dialler. If it does, book the upgrade.
Do not assume your alarm is already IP-compatible. Many installed systems that look modern still have a PSTN dialler underneath.
4. Fire Alarms
Same problem as intruder alarms, with higher stakes. Commercial fire alarm panels that use a PSTN line to alert a monitoring station or the fire service will lose that capability when PSTN closes.
This is life-safety equipment. It must be assessed and upgraded by a competent fire alarm engineer, not a general electrician. Check your fire alarm service contract, identify who maintains the panel, and ask them directly about PSTN dependency. Get the answer in writing.
Regulatory compliance may also be a factor here. If your fire risk assessment assumes monitored detection, a failed dialler undermines that assumption.
5. Lift and Elevator Auto-Diallers
Building regulations require lifts to have an emergency phone. In most existing lifts, that phone connects via a PSTN line. Press the emergency button, it dials the lift company's monitoring centre.
After January 2027, that call will not connect.
Lift maintenance providers are aware of this and most are already offering IP replacements. If you manage a building with a lift, contact your maintenance contractor now. The work involves replacing the auto-dialler unit and potentially reconfiguring the monitoring service. It is not a quick job to book at short notice.
6. PDQ Machines and Card Payment Terminals
Older PDQ terminals processed payments by dialling out over a PSTN line. Most card machines issued in the last several years use broadband or a built-in SIM instead — but not all.
If you have a terminal that has been in use for five or more years and you have never thought about how it connects, check now. Look for a phone line cable plugged into the back of the machine. If you see one, contact your payment provider and ask whether the terminal needs replacing.
A card machine that fails to process payments at the point of sale is not a minor inconvenience. Get this confirmed before the deadline.
7. Fax Machines
Fax runs over PSTN. Traditional fax machines will not work after the switch-off.
You have two practical choices. The first is IP fax, also called fax-to-email or T.38 fax. This routes fax transmissions over an internet connection, keeping your existing fax number and allowing you to send and receive via email. The second option is to stop using fax entirely. Email with PDF attachments does the same job and is already accepted as legally valid in most contexts.
Some regulated industries — legal, medical, certain public sector functions — still mandate fax. If you are in one of them, move to an IP fax service. If you are not, now is a reasonable time to retire the machine.
8. Door Entry and Intercom Systems
PSTN-connected door entry systems are common in offices, apartment blocks, and commercial premises. The intercom unit at the front door dials a phone number — your office line, your flat, your reception desk. After the switch-off, that call will not complete.
IP-based intercom and access control systems are a direct replacement. Many connect over your existing network cabling. If you manage the building or are responsible for office access, get a survey done and plan the replacement.
9. DECT Base Stations Wired to PSTN
Cordless DECT phones are common in small offices. The base station often connects directly to a PSTN socket, with multiple handsets roaming around the building.
The handsets themselves are usually fine. It is the base station that has the PSTN dependency. Replace the base station with one designed for VoIP, or connect the existing base station through an ATA. Some modern DECT systems connect natively to a VoIP system — check the model before assuming.
10. Medical Alert and Personal Emergency Response Systems
"I've fallen and I can't get up" devices — personal alarms worn as a pendant or wristband — typically connect via a PSTN line in the home. When the button is pressed, the device dials a monitoring centre.
These devices protect vulnerable people. If the PSTN line in the home goes, the alarm cannot call for help.
Service providers in this sector are required to upgrade their equipment. If you are responsible for someone who uses one of these systems — a family member, a care home resident, a supported-living tenant — contact the service provider directly and confirm they have a migration plan in place. Do not assume it has already been handled.
What to Do Next
Work through this list as a checklist. For each category that applies to your business or premises, identify who is responsible and what action is needed.
Most of these upgrades take time to book and complete. Alarm engineers, lift contractors, and intercom specialists are already seeing increased demand. The closer you get to January 2027, the longer the wait.
For your phone system specifically, the solution is straightforward. Moving to a VoIP service solves the landline problem immediately, usually saves money, and gives you features — call recording, auto-attendant, a mobile app — that a PSTN line never could.
Ready to sort your phone system before the deadline? Start your free 14-day trial — no card required, live in 10 working days. Get started → or call us on 0330 043 2388 No tie-in, no setup fees. Most businesses are fully live within 10 working days.
Frequently Asked Questions
When exactly is the PSTN switch-off?
The confirmed deadline is 31 January 2027. Openreach has been stopping new PSTN line installations since September 2023. The full network closure happens at the end of January 2027.
Will my broadband stop working when PSTN is switched off?
If you are on ADSL, yes. ADSL runs over the copper telephone network and will be switched off alongside voice services. Upgrade to FTTC, FTTP, or a 4G/5G connection before the deadline. If you are already on a fibre or cable broadband product, your broadband is not affected.
Does the PSTN switch-off affect mobile phones?
No. Mobile networks operate entirely separately from the PSTN copper network. Your mobile phone and mobile data are unaffected.
I have a monitored burglar alarm. Will it still work after January 2027?
Only if it has been upgraded to use an IP or GSM communicator instead of a PSTN dialler. Contact your alarm maintenance company and ask them to confirm in writing how your system communicates with the monitoring centre. If it still uses a phone line, book the upgrade now.