Quick answer
The phones are the easy part. The things that catch businesses out are everything else that quietly signals over a copper pair: intruder and fire alarm signalling, lift emergency phones, older card terminals, door entry intercoms, telecare and nurse call, fax machines, and plant or telemetry alarms. Each needs its own replacement, arranged with the company that maintains it - not your phone provider. Two of them (alarms and lifts) carry the longest lead times in the whole migration, so those are the calls to make first.
When businesses think about the phone switch-off, they picture handsets. But the analogue line often quietly powers far more, and these can be the riskiest part of the migration precisely because they are forgotten. This guide is the inventory: how to find every device, what replaces it, who arranges it, and the order to tackle them in.
Why this matters
The PSTN switch-off retires the analogue network entirely on 31 January 2027. Anything that signals over a copper line is in scope. Because these devices are easy to overlook and some are safety-critical, they deserve their own line in your plan.
The failure mode that makes this genuinely dangerous is that most of them fail silently. A phone that stops working is obvious within minutes. A monitored alarm that stops reporting still makes a noise, so the building sounds fine while nobody is being told. A lift emergency phone that no longer connects looks exactly like one that does. You find out when you most need it to work.
The full inventory
| Device | How it uses the line | What replaces it | Who arranges it |
|---|---|---|---|
| Intruder alarm signalling | Dialler or legacy monitored signalling to an alarm receiving centre | Dual-path IP signalling (broadband + mobile) | Alarm company - see alarm systems |
| Fire alarm monitoring | Dialler or dedicated signalling path | IP signalling, usually dual-path | Fire alarm maintainer |
| Lift emergency phone | Analogue line to an autodialler in the car or machine room | Battery-backed mobile (GSM) lift unit | Lift company - see lift lines |
| Card payment terminal | Older terminals dial out to authorise | IP, WiFi or mobile terminal | Card provider - see card machines |
| Telecare / pendant alarms | Analogue dispersed alarm unit dialling a monitoring centre | Digital telecare equipment | Telecare supplier - see care settings |
| Nurse call / warden call | Some dial out or link buildings over lines | Depends on system; ask the maintainer | Nurse call maintainer |
| Door entry / gate intercom | Dials a phone to let someone in | IP or mobile-based intercom | Manufacturer or installer |
| Fax machine | Modem tones over the analogue line | Cloud fax to email, or cancel it | Telecoms provider, or nobody - see fax after the switch-off |
| Plant, fridge and temperature alarms | Dial out when a threshold is crossed | IP or mobile module | Equipment supplier |
| Telemetry and remote monitoring | Dials home with readings | IP or mobile module | Equipment supplier |
| Older CCTV backhaul | Dial-up on legacy installations | IP over your network | CCTV installer |
| EPOS and vending diallers | Dial out for updates or reporting | IP or mobile | Equipment supplier |
| Lines for remote engineer access | A line purely so a supplier can dial in | Usually IP remote access | The relevant supplier |
Read the right-hand column carefully. Alarm, lift, telecare and card terminal replacements all belong to somebody else. This is the single most important thing to take from this article: no telecoms provider's migration plan includes your alarm or your lift. Ours does not either - what we do is coordinate around their dates and make sure nothing is ceased before it is proven.
How to find them
Twenty minutes with a notepad beats any amount of guessing.
- Pull three months of bills and list every standing charge separately from call charges. Count the lines.
- Compare that count with the phones you can see. A gap means something else is using a line.
- Walk the building. Every room, including plant rooms, basements, cupboards, lift machine rooms and the space behind reception.
- Follow the cables. Look for the flat phone cable (RJ11) running to anything that is not a phone.
- Ask the people who work there. Somebody remembers the fax line, or the line the alarm engineer used.
- Mark anything you cannot identify as "unknown". Do not assume it is spare.
That last point is worth stating plainly: never cease a line you cannot identify. Cancelling an unexplained line is how businesses discover, after the fact, what it was feeding. Investigate first. Our line replacement mapping guide helps you match each line to its replacement once you know what it does.
Priority order: risk against lead time
Not everything deserves equal urgency. Work in this order:
| Priority | Devices | Why |
|---|---|---|
| 1 - This week | Lift emergency lines, monitored alarms, telecare, nurse call | Safety-critical and long lead times. Both reasons point the same way |
| 2 - This month | Fire alarm monitoring, door entry, plant and temperature alarms | Important, and dependent on third parties |
| 3 - Next | Card terminals | Quick to sort, but check the contract attached |
| 4 - Whenever | Fax, EPOS diallers, remote access lines | Often the answer is simply to cancel the line |
The reason safety-critical items and long lead times coincide is not a coincidence: the equipment that matters most is maintained by specialist trades with finite capacity, and the whole country is migrating at once. Four to twelve weeks is the normal range now and it is lengthening.
If you want the connectivity and phone lines handled around your specialists' schedules, get a no-obligation quote - we will work to their dates rather than ours.
The shortcut to avoid
There is a tempting fix that gets offered a lot: plug the existing device into an analogue telephone adapter on a digital line, and carry on.
For an ordinary handset, or an undemanding device where nothing depends on it, that is a reasonable answer. For anything safety-critical it is not, for three specific reasons:
- Signalling behaviour. Older diallers rely on analogue tones and timings that do not always survive conversion reliably.
- Power. The adapter and router die in a mains failure, where the old line did not - and a power cut is exactly when a lift phone or an alarm matters most.
- Silent failure. Purpose-built replacements supervise themselves and report their own faults. An adapter does not tell anyone when it has stopped working.
So: adapters are fine for phones. They are not the answer for alarm signalling, lift emergency lines, or telecare. If somebody offers you an adapter for those, decline it and call the specialist.
Power and resilience planning
Unlike a forgotten back-office handset, many of these devices are critical, and they were designed around the copper line's quirk of carrying its own power. Their replacements generally depend on mains power and a working connection, so resilience becomes a deliberate task rather than an assumption:
- Battery backup (UPS) on the router, switches and any equipment carrying signalling - sized for a realistic outage, not five minutes.
- A mobile path for critical signalling, so a broadband fault does not silence everything at once. This is why dual-path alarm signalling is standard and why lift units use mobile rather than broadband.
- 4G or 5G failover on the connection, which is much easier to justify once phones, alarm signalling and card payments all share it.
- Testing, on a schedule, with results written down.
We cover the approach in landline resilience and failover.
What to do this week
- Walk the building and build the device list.
- Phone the alarm company, the lift company and any telecare supplier - all in the same week, not in sequence.
- Ask your card provider whether your terminals dial out.
- Get each specialist's quote, lead time and commissioning confirmation in writing.
- Put every date into one plan, with the line ceases last.
- Tell your insurer once alarm signalling has changed.
Our switch-off checklist is the full working version, and the deadline guide explains how the lead times shape everything else.
The bottom line
The switch-off is about far more than handsets. Alarms, lifts, card machines, telecare, fax and door entry can all depend on the analogue line, several are safety-critical, and most of them fail without telling you. Audit everything early, notice how many of the replacements belong to other suppliers, involve those specialists now rather than later, and plan resilience deliberately - then nothing important goes dark.
Want help auditing your site and coordinating the lines around your other suppliers? Get a no-obligation quote or call 0333 006 9399.
Getting unknown calls on a business line? Our free UK phone number checker shows which network or provider Ofcom allocated any number to, and whether the range is in service — no sign-up.
Frequently asked questions
What devices are affected by the phone line switch-off?
Anything that signals or dials out over the analogue line: intruder and fire alarm signalling, lift emergency phones, older card payment terminals, telecare and nurse call systems, door entry intercoms, fax machines, plant and temperature alarms, telemetry, some older CCTV, and lines that exist purely for a supplier's remote access.
Will my alarm still work after the switch-off?
It will still detect and still sound, but if it signals to a monitoring centre over a phone line, that reporting stops - and nothing in the building indicates it. Alarms need an alternative signalling path, usually dual-path IP with a mobile backup, arranged by your alarm company well before the deadline.
What about a lift emergency phone?
Lift emergency lines are safety-critical and must keep working in a power cut, so they cannot move onto office broadband. They usually need a dedicated battery-backed mobile unit, fitted by your lift maintenance company, and a mobile signal survey at the unit's location should be done before anything is ordered.
Do card machines work after the PSTN switch-off?
Most already do, because they connect over broadband, WiFi or mobile data. Older terminals that dial out will stop authorising transactions and need replacing or reconfiguring by your card provider. The hardware is often free, but check whether a new multi-year merchant services contract is attached.
Can I use an adapter to keep my existing devices working?
For ordinary handsets and undemanding equipment, often yes. For anything safety-critical - alarm signalling, lift emergency lines, telecare - no. Adapters lose power with your router, older diallers do not always work reliably through them, and crucially nothing reports the failure, so you believe you are protected when you are not.
Who is responsible for migrating these devices?
Whoever maintains each one: your alarm company, your lift maintenance company, your telecare supplier, your card provider, your door entry installer. Your telecoms provider handles the lines and connectivity underneath. No phone provider's migration includes your alarm or lift, which is why the device audit has to be yours.
How do I find every device using a phone line?
Compare the number of lines on your bill with the number of phones you can see, then walk the whole building - including plant rooms, basements, lift machine rooms and cupboards - following the flat phone cable to anything that is not a phone. Ask long-serving staff too. Mark anything unexplained as unknown, and never cease a line you cannot identify.