Copper Retirement: What's Still Plugged Into Your Old Phone Line (And What to Do About It)

Somewhere in your building there is a cable you have never thought about. It leaves a small grey box in a cupboard, slips through a wall and turns up in a green cabinet at the end of the road. For years it has carried your card payments, your alarm arming signal and the occasional fax nobody admits to sending. It is being retired, and the timetable has stopped being theoretical.

Openreach is closing the public switched telephone network (PSTN), along with the ISDN services that sit on top of it. The stop-sell of new copper lines is scheduled for 31 January 2027, and the network is due to be switched off completely by the end of that year. From a standing start in late 2026 that sounds like plenty of time. It is not, once you factor in alarm engineers, lift contractors and whoever actually installs your tills.

What is really being withdrawn

It is tempting to picture the switch-off as an engineer pulling one plug. Commercially, the change happens first: you stop being able to order an analogue line, then the service behind the line stops. Businesses already on full fibre or a fibre-with-no-voice product have nothing analogue in the path at all, and their calls simply ride the internet connection. The awkward cases are the older setups — a standard line with broadband layered on top, an ISDN30 with a dozen channels, a dedicated line that exists purely so the alarm can ring out.

One thing worth saying plainly: your broadband rarely vanishes overnight, but where voice and data are bundled, it is the bundle that changes. Ask your provider to confirm in writing what is being migrated, what replaces it and what happens to the monthly cost afterwards.

The kit quietly relying on a phone line

This is where most small businesses get caught out, because the list is longer than anyone expects:

• Intruder alarms using PSTN or Redcare signalling, or dual-path setups where one path is copper. The panel may be perfectly healthy; the communicator inside it is the problem.
• Fire and panic alarms that report to an alarm receiving centre (ARC).
• Card terminals and EPOS tills with a dial-up fallback. Most modern PDQs are IP or SIM based, but the spare unit in the drawer often isn't.
• Lift, stairlift and platform emergency lines, which have their own standards (BS EN 81-28) and an insurance inspector who will eventually ask questions.
• Telecare pendants and pull cords in care settings, which are the highest-stakes item on the list because they fail silently.
• Fax machines, franking machines and the till modem in the warehouse that nobody has touched since 2019.
• Door entry systems, gate intercoms and CCTV diallers that ring a mobile when someone presses a button.

If you have never done it, spend twenty minutes with a torch and photograph every socket in the building. You will find at least one surprise.

Why a plug-in adapter is not a plan

Analogue telephone adapters are cheap and perfectly decent for a fax machine or a basic handset. They are not a sensible answer for anything that has to raise an alarm. Monitored systems need the panel and the receiving centre to agree on how signals travel, and they need to keep working when the power is off or the broadband is down.

A router that takes ninety seconds to reboot after a power cut is not an emergency line. For most monitored alarms the practical fix is a new communicator — IP signalling, or dual-path IP plus mobile — fitted inside the existing panel, followed by a test call to the ARC. Some panels are too old to take one, in which case you are pricing a replacement, and that conversation should happen months before the copper goes quiet rather than weeks.

A migration checklist for a normal-sized firm

1. Map your numbers. Write down every number you own, what it does and who answers it. Include the fax line, the alarm line and the one on the side of the van.
2. List every device on a socket. Alarms, lifts, tills, franking, intercoms, telecare, CCTV. Photograph the labels.
3. Check contract end dates. Moving mid-term can be expensive; moving three months late can be worse.
4. Call the alarm and lift people first. They book up, and their lead times are the real deadline.
5. Decide how voice will work. A hosted VoIP service, a digital voice product from your broadband supplier, or a softphone your team already has through Microsoft Teams.
6. Confirm number porting in writing. Ask specifically whether each number can be ported and how long the port takes.
7. Plan for outages. A small UPS on the router and ONT, a mobile-based fallback for critical lines, and a printed list of who to ring when it breaks.
8. Test everything, out loud. Ring the alarm, send a test fax, page the lift, call your own main number from a mobile and check the greeting is still yours.
9. Update your asset register and incident notes. Future-you will be grateful.
10. Keep the old service alive for a fortnight where you can, and don't cancel anything until a test has passed.

The alarm conversation nobody wants to have

Alarm signalling is the single biggest source of unpleasant surprises in this whole migration. Many panels installed before 2020 were built around a copper dialler, and a fair number of small firms assume the alarm company will 'sort it'. They will, eventually — but the receiving centre has to support the new signalling path, the communicator has to be compatible with the panel, and someone has to physically attend to test it. None of that happens on a Friday afternoon when the line stops working.

Ask three questions of your alarm provider: what signalling do I have now, what will replace it, and can you give me a date in writing before the copper is withdrawn?

Power cuts, broadband wobbles and other boring risks

Digital voice depends on electricity and connectivity, neither of which is guaranteed. For a business with a couple of staff and a mobile each, a UPS on the router and a sensible call-diversion plan is usually enough. For anything with a monitored alarm, a lift or a vulnerable person on site, the answer needs to be more robust — battery-backed equipment, a secondary connection on a different technology, or both.

What to do this week

Three things: walk the building and list the sockets, ring your broadband supplier and ask what is happening to your line specifically, and email your alarm company asking for a migration date. That is an afternoon's work. Do it now and the switch-off becomes a diary entry rather than a small crisis.