What does the PSTN switch-off mean for construction sites, yards and new-build handovers?

Why is construction different from other businesses?

Our general guide to the PSTN switch-off covers the timeline, the device-by-device risks and what happens to lines left on the old network. This article covers what's specific to construction, because a contractor meets the switch-off in three places at once.

The first is your own yards, depots and offices, where alarms and gates installed years ago still dial out over copper. The second is live sites, where you need phones and alarm links for months but can't order an analogue line. The third is the buildings you hand over, where a lift phone or door entry panel without a working digital line becomes your client's problem on day one, and often a snagging dispute for you.

The date is fixed. Openreach said in July 2026 there is "no extension to the deadline", and about 350,000 business premises were still to move (Openreach, 31 July 2026). Wholesale rental on legacy lines rose by 40% in July 2026 and again in October 2026, so staying on copper is already the expensive option.

What needs checking at yards and depots?

Yards are where forgotten phone lines live. Walk each one with the last phone bill and check every device against this table.

Watch the mobile generation, not just "GSM". Many older "digital" replacements were 2G or 3G autodiallers. All UK 3G networks are now switched off, and the networks will withdraw 2G between 2029 and 2033: EE from May 2029, O2 from summer 2029 and Vodafone during 2030 (Ofcom, August 2026). A 2G unit fitted today will need replacing again within a few years. Ask for 4G, ideally with a SIM that can roam across networks, because yards on the edge of towns often have patchy coverage from any single network.

Mind the power. A copper line carries power from the exchange, but a fibre router or 4G unit doesn't, so battery backup must cover the router as well as the panel.

How do you get phones and alarm links on a temporary site?

You can't order a new analogue line for a site cabin. Openreach stopped selling new analogue lines nationally in September 2023, so every new site is already digital whether you planned it or not.

In practice, site cabins use a 4G or 5G router, upgraded to a fixed line on long projects. Our construction guide chapter on site connectivity covers how to choose. The phone side is simpler than it used to be. A cloud phone system makes the site office an extension of head office, and the site manager's calls follow them to a mobile or Teams. Nobody needs a "site phone line".

Site security systems, such as tower CCTV, wireless site alarms and hoarding intercoms, usually signal over mobile networks already. Check that each unit is 4G rather than 2G or 3G, and whose account the SIM is on.

Who orders the digital line for a new building's lift and door entry?

This is where handovers go wrong. A new building might have a lift emergency phone, a door entry system, a fire alarm link to a monitoring centre, and sometimes a refuge or accessible toilet alarm that calls out. Each needs a working digital line or SIM before the building can be handed over. Each is usually installed by a different specialist, and none of them thinks the line is their job.

The Lift and Escalator Industry Association (LEIA) is clear that the telephone line for a lift alarm is typically the building owner's responsibility, not the lift maintenance company's, and that routers and adapters need their own backup power (LEIA, December 2021). Lift emergency phones built to the EN 81-28 standard make an automatic test call at least every 72 hours, so a line that dies after handover is detected, but only if somebody receives the failed test.

Settle it in three places:

In the contract. The employer's requirements should say who provides each line or SIM during construction, who pays for it, and when the account transfers to the client, factor or facilities manager.

In the programme. Fixed lines need Openreach. For developments of 20 or more homes or commercial units, Openreach builds full fibre free of charge, and smaller sites pay a contribution. Plots connected to copper instead of full fibre are charged a flat £2,500 each (Openreach, September 2026). Register the site early, because a lift that can't be commissioned for want of a line holds up practical completion.

In the handover pack. Record every line, as in the table below.

Put it in the operation and maintenance (O&M) manual and the health and safety file, and walk the client or factor through it. The worst outcome is a SIM on the installer's trial contract that lapses three months after handover, leaving a lift phone that nobody knows is dead.

Worked example: a 48-flat development

Example (an illustration, not a real client): a contractor is building a 48-flat block in Falkirk with one lift, an audio door entry system and a common-area fire alarm, handing over to a housing association.

Because the site has more than 20 homes, the contractor registers it with Openreach at the start, and full fibre is built at no cost. The employer's requirements say the contractor provides a 4G SIM for the lift phone and door entry during construction, and the housing association takes over both SIM accounts at handover. The fire alarm uses a dual-path communicator arranged by the housing association's monitoring provider.

Two weeks before handover, the contractor tests each system: the lift phone reaches the lift company's call centre, the door entry panel calls a test flat, and the fire alarm link reaches the monitoring centre. The handover pack lists every SIM, account holder and test date, and the housing association signs for the accounts. None of it is complicated. It just has to be somebody's job.

How Indigo does this. Indigo Unified Communications' free PSTN switch-off check lists every line at every site, what's connected to it and who supplies it, then recommends a cloud phone system (8x8, 3CX or Microsoft Teams Phone) and the broadband to run it on. New phones are installed during working hours alongside the old ones, and Openreach ports the numbers between 9am and 5pm. For new site cabins, our Glasgow team usually has 4G or 5G connectivity live within 2–3 working days. Take the free switch-off check →

What to do next

1. List every line at every yard, depot and office from the phone bills, and walk each site to match lines to devices.
2. Ask each alarm, gate and intercom supplier in writing whether their equipment works on a digital line, and insist on 4G rather than 2G.
3. Add a line and SIM clause to your standard employer's requirements or subcontract packages for lift, door entry and alarm installers.
4. Add a line register to your handover pack template, with account holders and test dates.
5. Take our free PSTN switch-off check, and see our construction connectivity page for site cabins.