PSTN switch-off checklist for UK small businesses

If you run a business from one building, there's a decent chance your phone line has things hanging off it you've never thought about. The card machine. The alarm panel. A fax that hasn't sent anything in years. The 2027 switch-off is going to expose every one of them, and I'd rather you found them with this PSTN switch-off checklist in hand than with a lift engineer on the phone.

The short version: find every copper line and everything plugged into it, sort the safety-critical kit first (lift phones, alarms, telecare), decide how your calls should work, port your number to an internet-based service, run old and new side by side, then cancel the copper. Openreach retires the analogue network on 31 January 2027.

We covered the why in the plain-English explainer. This is the version you print, tick off and hand to whoever runs the building.

Where the phone line actually lives

I've installed phone systems for small firms since 2012, and since 2015 at circle.cloud, the UK telecoms company I started that installs and supports phone systems for small businesses. The small businesses circle.cloud installs for have no comms room, so the phone system sits under a desk with the card machine, the alarm and the fax on the same few copper lines coming into the building, and I've traced those cables myself.

Nobody in the building chose any of it. It came with a contract, and it stayed because nobody wanted to be the one to touch it.

That's the picture to hold in your head. It isn't one phone line. It's a knot of things that all assume there's dial tone in the wall, put in over the years by companies who've never spoken to each other. The switch-off doesn't just end your calls. It ends every one of those at the same moment.

And the clock's been running for a while. Openreach stopped selling new analogue and ISDN lines in September 2023, and the wholesale rental behind the lines still running rises to 20% above its old level in April 2026, 60% above it in July and 100% above it in October. Those are wholesale increases charged to providers, so what reaches your bill depends on who you're with. Either way, the old line is disappearing while the cost of keeping it goes up.

The PSTN switch-off checklist, in order

Work through these top to bottom. Nothing here needs a consultant, just an afternoon, a torch and a few phone calls.

Now: find out what you've actually got

You can't plan a move you haven't mapped, and in my experience the map is rarely what the owner thinks it is.

• Walk the building and find every phone socket. Note what's plugged into each one, not just the desk phones.
• Pull your last few phone bills. They list every line you're paying for, including the ones nobody remembers ordering.
• List anything that dials out on its own. This is the step people skip, and it's the one that causes the panic later. Intruder alarms reporting to a monitoring centre, lift emergency phones and their autodiallers, monitored fire alarms, door entry and gate intercoms, card machines that dial rather than use your network, telecare or pendant alarms in any kind of care setting, fax machines, older tills, and CCTV that alerts over a phone line.
• Note who supports each device. The alarm company, the lift firm, the card machine provider. You'll talk to each of them separately, and the switch-off is their problem to help you with, not only yours.

Three to six months out: sort the safety-critical kit first

Anything a person's safety depends on gets sorted before your ordinary calls. The lift phone doesn't care how nice your new desk phones are.

• Ring the maintainer of each safety-critical device (lift phone, fire alarm, intruder alarm, telecare) and ask directly: does this already have an internet-based replacement, and when is it being fitted?
• Get a date in writing for each one. "We'll sort it before the deadline" isn't a plan.
• Ask about backup power. A copper line carried its own power, so a basic phone worked in a power cut. The replacement needs broadband and mains, so a power cut can take the line with it unless there's a battery in place. For a lift phone or an alarm, that's not a detail to skip.

Weeks to months out: decide how your calls should work

This is where most guides say "get VoIP" and stop. True, and not much use on its own.

• Decide who needs to be reachable, and how. Not every desk needs a phone. A shared front-desk line is a different problem to an owner who's mostly out at client sites.
• Check what happens to your number. You can normally keep it when you switch providers. Moving it is called porting, and it's a routine, regulated process, not a renegotiation. I've written up how porting actually works if you want the detail.
• Choose a provider and get a real answer on timelines, not a sales pitch. A serious provider tells you plainly how long your port will take and what they need from you.
• Plan the cutover itself, running old and new side by side rather than flipping in one go. The switch without downtime guide walks through that sequencing.

The week before

Iron out the niggly bits while the old line is still there to fall back on.

• Test the new setup properly before you trust it: call in from a mobile, check the out-of-hours routing, confirm voicemail lands with the right person.
• Confirm every safety-critical device from the first step is actually done, not just booked in.
• Pick a calm day for the cutover. Not your busiest morning, not the day before everyone's off.
• Tell the team what's changing and when, so nobody's caught mid-call.

Cutover day and the week after

• Keep the old service active until your number has moved and the new one's working. With One Touch Switch, the old service normally ends on its own. If you're managing it yourself, agree any overlap and cancellation with both providers.
• Check calls are landing where they should, on every number, not just the main line.
• Chase anyone still using an old temporary or forwarding number and redirect it.
• Confirm the old service has ended and the billing has stopped. Check anything bundled with it separately.

The last thing under the desk

None of this is technically hard. It's a mapping exercise and a handful of phone calls, in the right order. What makes it hard is leaving it until the same month everyone else rings their alarm company, and then discovering the lift phone dials out on a line you didn't know you had.

Once your calls run over the internet instead of copper, you get more than compliance. Your number stops being tied to a socket in one building; someone working from home answers the same line as the desk they used to sit at, and the line moves with them to a laptop or a mobile. That's what we're building with Olatti: a business line that lives wherever your team does, on a desk phone or in a keystroke, with none of the boxes on the wall.

When you're through this list, the only thing left under that desk should be a network cable. If you'd like to be off the copper and calling the modern way well before it goes dark, join the Olatti waitlist and we'll bring you in early.