The PSTN Switch-Off: What It Means for Your Business

There is a telephone inside your lift. If the lift stops with someone in it, they press a button and it dials out. Ask who is responsible for that phone and where it plugs in, and in most buildings you will get a long pause.

That phone is the reason the PSTN switch-off matters more than it first appears. The UK’s analogue telephone network — the public switched telephone network, and the ISDN lines that ride alongside it — is being retired. Everything moves to digital voice carried over broadband. Most coverage of this focuses on desk phones, which is the easy part. The hard part is everything else in your building that quietly dials out over a copper pair.

First, the date — and a warning about it

The industry is currently working to the end of January 2027 for the retirement of the old network. Treat that as a planning anchor rather than gospel. The deadline has already moved once, having originally been set for the end of 2025, and it was pushed back partly because of the risks around vulnerable users and telecare equipment.

So the sensible position is this: work to the current date, but confirm the position for your specific lines with your own provider, and check again if you are planning anything long-dated. Regional stop-sell rules also mean many areas cannot order new analogue services at all now, which can catch you out well before any national deadline.

The audit nobody does

Desk phones are obvious and easy to replace. The following are neither, and every one of them has been found still sitting on an analogue line in a working business:

• Lift emergency phones. Legally required to work, maintained by a lift company, connected to a line nobody in the building can account for.
• Intruder and fire alarm signalling. Many alarm panels report to a monitoring centre down a phone line. If your insurer requires monitored signalling, this is a policy condition, not a convenience.
• Door entry and gate intercoms. Especially on shared sites, industrial units and older office buildings.
• Care alarms and pendant systems. Critical in care homes, sheltered housing and any setting with vulnerable people. These need the most care and the earliest attention.
• Card payment terminals. Some older countertop units still dial out to authorise.
• Franking machines. They phone home to top up postage credit.
• Fax lines. Still lodged with the NHS, some courts and some insurers, and still occasionally used.
• Building management and metering kit. Remote-read meters, boiler telemetry, refrigeration monitoring.

Walk the building and follow the cables. Then cross-check against your telecoms bill: every line you are paying for exists for a reason, and any line you cannot explain is exactly the one that will fail. Where a device is safety-related — lifts, alarms, care systems — call the maintaining company early. They will have a migration path, and their diaries fill up as deadlines approach.

What replaces it

For voice, the replacement is a digital service carried over your internet connection, either as a hosted phone system or as a digital line into an existing setup. Modern VoIP business phone systems generally do more than the lines they replace — numbers follow people to mobiles and laptops, call routing changes without an engineer visit, and adding a user is an admin task rather than an installation.

For the other equipment, the answers vary. Alarm panels usually move to IP or mobile signalling, often with a dual-path unit so a broadband failure does not leave the site unmonitored. Lift phones typically move to a GSM unit with its own battery, which sidesteps the building’s network entirely. Card terminals move to broadband or mobile. Some devices simply need replacing, and finding that out in month one is far better than in the final week.

Two things that change on the day you switch

Power. An analogue line carried its own power from the exchange, which is why a basic corded phone still worked in a power cut. A digital line does not. When the electricity goes off, your router, your switch and your handsets go off with it. The answer is a battery backup sized to keep the essential kit alive for a realistic period, mobile failover for the phone system, or an explicit rule that emergency calls go via mobile. Whichever you choose, decide it deliberately rather than discovering it during an outage.

Broadband becomes business-critical. The moment your phones ride on your internet connection, a line that used to be an inconvenience when it wavered becomes the thing that silences your business. That raises real questions about the connection itself, and about whether a backup route is now justified — our guide to business broadband options covers the trade-offs. It also raises the standard of the network inside the building: voice traffic is unforgiving of a tired switch, an overloaded router or Wi-Fi that was never designed for it.

A sensible order to do this in

Start with the audit, because everything else depends on knowing what you have. Deal with safety and compliance items next — lifts, alarms, care systems — since those have the longest lead times and the least tolerance for a gap. Then check your connection and internal network can carry voice properly, and fix that before the phones arrive rather than after.

Only then move the phones themselves, keeping numbers ported and the old service running in parallel until the new one is proven. Finish by testing the failure cases nobody tests: pull the power and see what still rings, then confirm that the alarm and the lift phone genuinely reach the other end.

Give yourself months rather than weeks. Providers, alarm engineers and lift companies are all working to the same deadline, and the businesses that leave it late will be competing for the same appointments. If you would like a hand mapping what is actually connected in your building and planning the order of work, ongoing managed IT support is where this kind of thing normally gets picked up long before it becomes urgent.