PSTN switch-off: alarms, card machines and lift phones

Moving your phones to VoIP is the easy part of the PSTN switch-off. Alarms, card machines, lift phones and the franking machine catch businesses out. Nobody remembers they're plugged into a phone line until they stop working. This guide goes through each device: whether it relies on the old line, what fails, and the usual fix.

For the dates and background, see our PSTN switch-off guide. The short version: Openreach aims to have every line off the old analogue network by 31 January 2027.

The short answer

• Anything plugged into a phone socket needs checking, not just phones. Openreach's own list includes intruder alarms, lift lines, chip and pin machines, telecare, CCTV and monitoring equipment.
• Your phone company doesn't know what's plugged in. Finding out is down to you, and the government's advice is to ask each device's supplier before buying anything new.
• The usual fixes depend on the device. Phone-type equipment, like lift phones, door entry and fax, usually just needs an analogue telephone adaptor (ATA), which keeps it working over VoIP. Alarms and other auto-diallers need IP signalling with a GSM (mobile) backup, or GSM alone.
• Alarms and lift phones are normally the alarm or lift company's job to upgrade, but you have to ask them.
• Test everything the day after your line moves.

Which alarms and devices does the PSTN switch-off affect?

On migration day, your extension sockets stop working. Calls run through the router instead. Openreach calls alarms, telecare and lift lines "special services", and each one has to connect through that router or find another route. Here's how the common devices fare.

Most of these devices have been sold in digital versions for years, so plenty of businesses will find they're already fine. The point is to know, not to assume.

What happens to our alarm?

Openreach's briefing for the alarm industry says the trade has relied on analogue lines as its main signalling path. It warns that monitored alarms "may be left disconnected" when a line is upgraded on site. Line-cut monitoring is affected too, because it relied on the 50V charge in a copper line.

The National Security Inspectorate (NSI) advises contacting your alarm or maintenance company before your line is upgraded. Not every system needs replacing. If yours does, ask for a written quote that explains why.

You'll sometimes hear that an alarm dialler can simply plug into an adaptor on the new router. In our experience that's a no-go: we've tested quite a few diallers and speed diallers through ATAs, and they aren't reliable enough for something that has to get through. The dependable route is IP signalling with a GSM (mobile) backup, or GSM on its own.

If your alarm is monitored, it's worth asking your insurer too, as cover can depend on the monitoring working.

Card machines, tills and franking

Most recent card machines use broadband, WiFi or a mobile SIM, so they won't notice the switch. The ones to watch are older countertop terminals with a cable to a phone socket. Your card provider can tell you which you have.

Tills and EPOS systems are similar. Modern ones use the network, but some older set-ups use a modem for card payments or end-of-day reports. Franking machines that top up postage over a phone line need moving onto your network before the line goes. If the model can't do that, it needs replacing.

Lift phones and door entry

Every lift has an alarm button that calls a rescue service, usually through an emergency phone unit plugged into a phone line. Openreach's lift-industry briefing splits the job. The lift company maintains the alarm hardware. The lift owner looks after the router and its battery backup. It also notes that the metal around a lift can weaken a mobile signal, so a 4G unit needs a proper signal check.

For lift phones, the fix is usually simpler than people expect. We fit an analogue telephone adaptor (ATA), usually a Grandstream HT801, which the existing lift phone plugs into. The analogue equipment in the lift keeps working exactly as before, and the adaptor carries the call over VoIP. Put the router and adaptor on battery backup, and test the alarm button with your lift company present.

Door entry and gate intercoms that dial a phone when a visitor presses the button are handled the same way, with an ATA. Check with the installer, then test.

Telecare and personal alarms

If you run care premises or housing, or someone relies on a personal alarm, tell the phone provider. The government announced an agreement on 11 March 2024: no known telecare user will be moved to a digital line until a working alternative is confirmed. That only works if the provider knows the device is there.

How to audit your building

1. Walk the building. Find every phone socket, including ones in plant rooms, lift motor rooms, the post room and behind the till.
2. Follow each cable to whatever it feeds and write it down: device, make, model, which line.
3. Check your phone bill for lines you can't account for. A line nobody answers is usually there for a device.
4. Ask each supplier (alarm company, lift company, card provider, franking supplier) whether the device works over a digital line, and what they recommend if not. Get their answer in writing.
5. Book the upgrades before your line moves, not after.
6. Test after migration. Ask the alarm company to send a test signal, press the lift alarm with the lift company present, run a card payment and buzz the door entry.

Power cuts

A copper line carries its own power. A digital one doesn't, so an alarm or lift phone that now goes through the router stops when the power does, unless there's a backup. Openreach's guidance for both alarms and lifts is that the router may need battery backup. A small UPS (battery backup unit) on the router and any adaptor usually covers it, and we can supply one. Our switch-off guide has more on power cuts and what Ofcom expects from providers.

How we can help

We'll walk your building with you and list every line and what's plugged into it. Then we'll tell you which items move with your phones and which need your alarm, lift or card-machine company. We supply and fit the ATAs for lift phones, door entry and fax, plus 4G backup routers and UPS units. We can't certify your alarm or your lift, but we can make sure nothing gets missed. Our hosted VoIP phone system is from £7 +VAT per user a month, plus £2.50 +VAT per number, and we can check your business broadband is up to carrying everything. Get in touch for a free initial survey.