If you run a UK business and you're still using a traditional phone line, there's a date you need to know: 31 January 2027.
That's when BT Openreach will permanently switch off the UK's Public Switched Telephone Network — the copper-wire infrastructure that has powered landlines, broadband, and dozens of other business-critical systems for over a century. Once it goes off, it doesn't come back on.
The problem? Only 18% of UK SMEs have a solution ready. And 9% of businesses don't even know the BT switch off is happening at all.
This guide explains exactly what the BT PSTN switch off is, which systems are affected, why your costs are already rising, and what your business needs to do before the deadline. No jargon. No sales spin. Just the facts.
What Is the BT Switch Off?
The BT switch off — also called the PSTN switch off or the ISDN switch off — is the permanent shutdown of the UK's traditional analogue telephone network. From 31 January 2027, any device or service that relies on a copper phone line will simply stop working.
This isn't a gradual wind-down. It's a hard deadline. BT Openreach has already stopped selling new PSTN and ISDN lines as of September 2023. The network is already deteriorating — in 2024, significant PSTN resilience incidents increased by 45% according to Ofcom's Connected Nations report. The infrastructure is ageing, increasingly prone to failure, and expensive to maintain.
The switch-off has been on the horizon for years. It was originally planned for December 2025 before being extended to January 2027. That extension has led many businesses to assume they have plenty of time. They don't. With millions of UK businesses still needing to migrate, engineers and installation slots are already filling up — and costs for late movers will only increase.
It's Not Just Your Phone System — Here's What's Actually at Risk
This is where most businesses get caught out. They assume the BT switch off only affects their desk phones. It doesn't. Any device connected to a copper phone line will stop working on 31 January 2027, including systems you may not even realise are connected.
Here's what your business needs to audit:
- Traditional landline phones and ISDN systems — any analogue handset or on-premise PBX connected to copper lines
- Fire and intruder alarm systems — alarm panels that dial out to a monitoring centre over a phone line. This is a legal compliance issue, not just an operational one
- EPOS and card payment terminals — chip and pin or contactless machines connected via phone line
- CCTV and door entry systems — security systems that transmit footage or send alerts over a copper connection
- ADSL and FTTC broadband — both use copper as part of their infrastructure and will be affected
- Lift emergency phones — a legal requirement that must have a working emergency call connection at all times
- Fax machines — any fax line running over a copper phone connection
- Telecare and monitoring devices — personal safety and lone worker devices that connect over PSTN
Not sure which of these apply to your business? Download our free Business Readiness Checklist — it walks you through every system in under five minutes.
Why Are My Costs Already Going Up?
If you've noticed your phone line rental or maintenance bills increasing significantly over the past 12 months, the BT switch off is almost certainly why.
As BT reduces investment in the ageing PSTN network, the cost of maintaining legacy lines has risen dramatically. Many businesses are now paying 100% more — double what they were paying previously — just to keep their existing systems running. And that's before any migration costs.
Openreach has also confirmed staged wholesale price rises on legacy copper line rentals throughout 2026, with increases expected in April, July and October that will roughly double annual costs by the autumn. You are currently paying more and more for an infrastructure that is guaranteed to switch off.
The businesses that migrate now will almost always find that a modern VoIP or cloud phone system costs less per month than what they're currently paying to maintain their legacy lines. Migration isn't just about compliance — it's about cutting costs.
Why You Shouldn't Wait — Even Though It's "Still 2026"
We hear this a lot: "We've still got time." Here's why that thinking is dangerous:
The capacity crunch is already here. With millions of UK businesses still needing to migrate, installation engineers, hardware suppliers, and telecoms providers are booking up fast. The businesses that leave it until late 2026 will find limited availability, longer lead times, and higher prices.
Hidden dependencies take months to uncover. Most businesses don't realise how many systems rely on copper lines until they do a proper audit. Once you've identified everything, planning the migration, procuring equipment, testing it, and going live takes time. A thorough migration can take anywhere from 6 to 9 months. Starting now gives you that time. Starting in Q4 2026 means rushing — and rushed migrations cause downtime.
The network is already unreliable. A 45% increase in PSTN incidents in 2024 means faults and outages are already increasing. Every month you stay on legacy infrastructure is another month of growing risk.
A last-minute migration is a business risk. For many SMEs, even a single day of lost connectivity means missed calls, failed card payments, offline alarms, and real commercial consequences. A properly planned migration with a testing period eliminates that risk entirely.
What Does a Good Migration Look Like?
The good news is that migrating before the deadline doesn't have to be complicated or disruptive — if it's planned properly. Here's what a well-managed migration typically involves:
Step 1 — Audit your current setup. Identify every device and service in your business that relies on a copper line. This includes the obvious (phones) and the less obvious (alarms, card machines, broadband, CCTV). Our free checklist makes this straightforward.
Step 2 — Identify the right solution. The right migration path depends on your business size, the systems you're replacing, and your budget. Options include cloud-based VoIP phone systems, unified communications platforms, full fibre broadband, and SoGEA connections. An independent advisor will give you whole-of-market options rather than pushing a single product.
Step 3 — Plan the migration timeline. A good migration plan accounts for number porting (keeping your existing phone numbers), hardware installation, staff training, and a testing window before anything goes live.
Step 4 — Test before you switch. Run both systems in parallel for a period before fully cutting over. This catches any issues before they affect your customers or your operations.
Step 5 — Go live with confidence. With proper planning and testing, the actual switchover should be seamless — and your new system will typically be more reliable, more flexible, and cheaper to run than what you're replacing.
How ICA Can Help
At ICA, we're independent telecoms advisors — that means we're not tied to any single provider or product. We audit your current setup, identify everything that needs to change, and recommend the right solution from across the whole market. No single-supplier bias. No sales pressure.
We offer free, no-obligation consultations for businesses at any stage of the process — whether you're just starting to think about the switch off or you've already started migrating and need a second opinion.
Our solutions cover everything the switch off affects:
- Unified Communications — cloud-based phone systems with calling, video, messaging and collaboration
- VoIP and Voice — modern internet-based calling to replace your ISDN lines
- Connectivity — full fibre broadband and leased lines to replace ADSL and FTTC
- IT and Cloud — migrate your wider infrastructure away from legacy on-premise systems
Get Started Today — Free Business Readiness Checklist
The easiest first step is to find out exactly where your business stands. Our free one-page Business Readiness Checklist walks you through every system you need to audit before the January 2027 deadline. It takes less than five minutes and tells you immediately what action you need to take.
→ Download the free checklist and visit our BT Switch Off hub at ica.co.uk/btswitchoff
Or if you'd rather talk it through with an expert, call us on 0330 100 0810 or email enquiries@ica.co.uk. We're here to help — without the sales spin.
