Why devices, not phones, are the real risk
Moving your phone calls to VoIP is usually straightforward. The problems come from equipment that quietly uses a phone line in the background, often installed years ago by a different supplier. When the line becomes digital, these devices can fail without anyone noticing until they are needed.
Openreach warned in July 2026 that around 1.5 million analogue lines had still not moved, and earlier in the year it reported that around 500,000 business lines were still on legacy services. Many of those are lines that only exist for an alarm, a lift or a card machine.
Intruder and fire alarms
Many monitored alarms use a “communicator” that dials the alarm receiving centre over a phone line. After the switch-off, that call may not connect reliably. Ask your alarm company whether your panel can signal over IP or 4G, ideally using a dual-path communicator that uses both, so the alarm still reports if your broadband goes down. If your insurer requires monitoring, check the new set-up still meets their conditions.
Lift emergency phones
Lifts must have a working way for trapped passengers to call for help. Many lift phones use a dedicated analogue line. The usual fix is a 4G lift line unit that replaces the copper line. Speak to your lift maintenance company early, as engineers get booked up close to deadlines.
Card machines and payment terminals
Older “dial-up” card terminals connect to the bank over a phone line. Most modern terminals use broadband, Wi-Fi or 4G instead. If your terminal still plugs into a phone socket, ask your payment provider for an IP or mobile terminal. It is usually a swap, not a big project.
Franking machines
Some older franking machines download postage credit by dialling out. Newer models connect over the internet. Check with your franking supplier whether your model is affected and whether a firmware update or replacement is needed.
Fax machines
Fax over digital lines is unreliable. If you still need to send or receive faxes, an email-to-fax service keeps your fax number working without a fax machine. Many businesses find they no longer need fax at all once they check.
Door entry, gate and building systems
Door entry panels, gate intercoms, building management systems, meters and telemetry units can also dial out over phone lines. List anything on site that has a phone cable plugged into it, then check each with its installer.
How to find every affected device
- List every phone line on your bills, including lines nobody answers.
- Trace each line to what it is connected to. Lines with no handset are often alarms, lifts or card machines.
- Contact each supplier and ask if the device works over IP or 4G.
- Plan the move so devices are switched before the old line is cancelled.
- Test after switching, especially alarms and lift phones.
What about power cuts?
Copper lines carried their own power, so some devices kept working in a power cut. Digital lines need power at your router. For critical devices, consider a battery backup (UPS) for your router, or a 4G connection that does not depend on your broadband.
How AVAIO can help
We offer a free PSTN audit for Kent businesses. We list every line, identify what is plugged into it and move your phones to VoIP from £14 per user per month, keeping your existing numbers. We also work with your alarm, lift and payment suppliers so nothing is left behind.