The PSTN switch-off is the closure of the UK’s old copper landline network and the move to digital calling over broadband. The final deadline is January 31, 2027, but the practical deadline is sooner because new legacy lines have been unavailable since September 2023.
At Microbyte, we’ve been operating since 1992 and we’re a 3CX Platinum Partner, so we deal with this as a business continuity job, not a phone swap. This guide explains what needs checking, what replaces the old service, and how to avoid a last-minute rush.
What the 2027 Deadline Means in Practice
By January 31, 2027, the UK will permanently retire the Public Switched Telephone Network (PSTN) and its digital overlay, ISDN. That means any service still depending on old copper must be audited, replaced, or moved to a supported digital route before the cut-off.
The Public Switched Telephone Network has functioned as the foundational architecture for United Kingdom telecommunications for over a century. However, the physical constraints of copper-based networks, coupled with rising maintenance costs and increasing unreliability, have forced a mandatory transition to digital, Internet Protocol (IP)-based connectivity.
The Timeline Has Changed, but the Direction Hasn’t
Revised Timeline: Evidence indicates that the final deadline for the old landline network and ISDN switch-off has been delayed from December 2025 to January 31, 2027. Openreach’s February 2026 update (openreach.com) says more than half a million business lines still needed to move at that point.
Operational Urgency: Despite the delay, a national “Stop Sell” order has been in effect since September 2023, meaning organisations can no longer purchase or expand legacy copper lines. If you’re moving office, adding headcount, or opening a branch, the new setup has to be digital from the start.
The Extension Was About Safety
However, following significant technological and safety challenges regarding the migration of vulnerable individuals and telecare systems, a 13-month extension was granted. This extension is generally viewed not as a permanent reprieve, but as a necessary reset to ensure public safety and network resilience.
That matters because the old network is already showing its age.
Why the Old Copper Network is Failing
Ofcom’s 2024 Connected Nations report recorded a sharp 45% annual rise in significant PSTN failure incidents. Through its Connected Nations reports, Ofcom has documented the precipitous decline in PSTN reliability (ofcom.org.uk), noting that service outages pose severe risks to commercial continuity and public safety.
The 45% increase in resilience incidents underscores that the old network is becoming dangerously unstable. For a business owner, that means this isn’t just a telecoms deadline. It’s a risk to payment taking, access control, alarms and customer service.
The Resilience Numbers Are Not Abstract
GOV.UK June 2025 telecare switchover update (gov.uk) also reported that over two-thirds of legacy lines had already migrated to Voice over Internet Protocol (VoIP), leaving fewer than 5.6 million operational at that time. By February 2026, Openreach said roughly 2.8 million lines still needed to move.
Where the Risk Shows Up
A failed line doesn’t always look like a failed telephone. It can look like a lift alarm that can’t call out, a payment terminal that drops, or a monitoring centre that stops receiving signals from an old device.
- Customer calls may fail or route to the wrong team.
- Fire and intruder alarms may lose their dial-out path.
- Door-entry systems may stop releasing access correctly.
- Fax machines, franking machines and older tills may need replacement.
- Lift emergency lines may need a certified alternative.
Once you accept the reliability risk, the audit stops being just a telephony job.
How to Audit PSTN Readiness
A readiness check should identify every device connected to copper, not just the obvious handsets on desks. GOV.UK guidance for estates (gov.uk) lists services that may rely on copper broadband or analogue lines, including fire alarms, lift lines, closed-circuit television (CCTV), card machines, printers and building management systems.
For most small and medium-sized organisations, the risk is hidden in cupboards, plant rooms and old supplier contracts. We often find that the line no one recognises is the one attached to something safety-related.
Devices That Often Get Missed
- Security and access: Fire alarms, intruder alarms, closed-circuit television (CCTV), and door-entry systems.
- Safety devices: Lift emergency lines, medical monitoring equipment and fall alarms.
- Commercial equipment: Electronic Point of Sale (EPOS) card machines, payment terminals, fax machines and franking machines.
- Site equipment: Environmental monitoring, specialist fridges, vending machines and building management systems.
- Voice services: Reception lines, call routing, old Private Branch Exchange (PBX) hardware and ISDN lines.
If any of these services could stop trading or create a safety issue, record them in your disaster recovery policy. The document should name the supplier, the line type, the location and the action needed.
A Worked Audit Example
Take a 40-user office near London Bridge. The obvious work is replacing reception handsets, but the hidden work might include a lift line, an alarm dialler, a card machine and a door-entry panel that still uses copper.
That is why our audits walk the building, not just the phone bill. We check sockets, cabinet labels, supplier invoices, contracts and anything that dials out.
The audit gives you the what. The replacement design gives you the how.
Replacement Options for the Copper Phone System
Copper cabling is being replaced by digital connectivity, usually Fibre-to-the-Premises (FTTP), Single Order Generic Ethernet Access (SoGEA) broadband, leased lines, or another Internet Protocol (IP) service. Voice calls then run through Voice over Internet Protocol (VoIP), cloud telephony, or Session Initiation Protocol (SIP) trunking.
Infrastructure Copper cabling Fibre-optic (FTTP) or SoGEA broadband is the practical shift most organisations need to understand. The old line carried both signal and power. The new setup depends on your local broadband, router, switches and power supply.
Old Network Versus Digital Voice
ISDN, introduced in 1986, runs over the same copper base but uses digital transmission for voice and data. Many older business phone system setups used ISDN2e or ISDN30 lines into a Private Branch Exchange (PBX), which is the box that manages internal extensions and external calls.
What the New Architecture Needs
The migration demands expertise in Unified Communications as a Service (UCaaS), Voice over Internet Protocol (VoIP), local network resilience, and hardware auditing. Unified Communications as a Service (UCaaS) means calls, voicemail, chat and meetings are managed as a cloud service rather than through a box in your comms room.
If you need the work tied into budget, risk and growth planning, our vCIO guide explains how a Virtual Chief Information Officer (vCIO) turns technical decisions into business plans. That is useful when the phone change affects branches in Peterborough, Stamford, Cambridge, Bedford, London, Woking, Lincoln, Grantham or Dubai.
A digital service is only as dependable as the power and backup design underneath it.
How to Keep Calls Working During Power and Broadband Faults
Historically, PSTN lines carried their own electrical current, meaning corded telephones and analogue alarm diallers continued to function during local power outages. Digital landlines cannot do that, so GOV.UK landline transition guidance (gov.uk) says routers and handsets need backup power if they must keep working during an outage.
Because digital voice services rely on local power, unlike the older exchange-powered model, providers and organisations need resilience measures such as battery backups. For managed IT service providers, this regulatory stance underscores the necessity of designing digital voice architectures that include Uninterruptible Power Supply (UPS) systems and cellular failover capabilities.
The Resilience Design
Use the migration to define the services that must stay available during a power cut, broadband outage, supplier fault or building incident. Then design backup around those services rather than buying generic voice equipment and hoping it covers the risk.
- Power the right kit: Put the router, firewall, network switch and core handsets on an Uninterruptible Power Supply (UPS).
- Add cellular failover: Use a router with 4G or 5G backup, so Session Initiation Protocol (SIP) registration can continue if wired broadband fails.
- Check call routing: Make sure inbound calls can divert to mobiles, remote teams or another office.
- Test emergency paths: Confirm lifts, alarms and monitoring centres still receive signals after migration.
- Document the failover: Record who checks the backup and how often it is tested.
Security and Recovery Planning
Where risk is higher, the phone project should sit beside cyber and recovery planning. The National Cyber Security Centre guidance for small and medium-sized organisations (ncsc.gov.uk) treats incident preparation as part of protecting uptime, money and reputation.
Microsoft Learn describes Microsoft Defender for Business (learn.microsoft.com) as endpoint security for small and medium-sized organisations up to 300 users. We cover the practical version in our Microsoft Defender article, because voice, devices and security now sit on the same network.
Once resilience is designed, timing becomes the next risk.
When to Start and What IT Will Cost to Wait
Openreach said legacy Wholesale Line Rental (WLR) prices would rise by 20% from April 1, 2026, then by a further 40% on July 1 and October 1, 2026. By artificially inflating the cost of legacy line maintenance by up to 40% in late 2026, network operators are forcefully incentivising the abandonment of copper infrastructure prior to the absolute 2027 cut-off.
As of May 11, 2026, the April increase is no longer a future warning. It has started. If your provider hasn’t contacted you, ask why.
A Practical Migration Plan
Treat the timetable as a controlled project rather than a supplier-led scramble. The best plans give each site a named owner, a device register, a porting date, a rollback route and a documented test before the old service is cancelled.
Businesses cannot purchase new non-fibre broadband, such as Asymmetric Digital Subscriber Line (ADSL) or standard Fibre to the Cabinet (FTTC) where withdrawal rules apply. Existing legacy infrastructure cannot be modified, moved, or expanded in the way many organisations expect.
Why Waiting Creates More Cost
The last-minute rush in late 2026 could create hardware shortages and an unavailable engineering resource. It also leaves less time to find edge cases, such as a warehouse alarm in Peterborough, a lift line in Bermondsey Street, or a payment device in a Lincolnshire site office.
We prefer a fixed monthly cost where possible because owners hate surprise IT invoices. That fits our Stamp Out Support approach: catch problems before they affect you, then remove the firefighting.
The plan works best when it has a named owner, not when it sits as a telecoms side job.
Who Should Own the Migration
The right owner is the person or partner who can join up telecoms, broadband, security, power, suppliers and business continuity. A strategic migration plan should cover the technology, but it should also cover downtime, staff communication, emergency calls, branch differences and supplier accountability.
At Microbyte, we handle this through our own engineers, not outsourced call centres. We support clients from Peterborough HQ, Bermondsey Street in London, Woking, Lincoln, Dubai Business Bay, Portland, Los Angeles and our Philippines-based 24/7/365 helpdesk and Security Operations Centre (SOC).
What A Good Owner Checks
- Lines and numbers: Which numbers must be kept, diverted or retired.
- Sites and branches: Which locations need onsite work, including London Bridge, Stamford, Cambridge, Bedford and Grantham.
- Suppliers: Which alarm, lift, payment and broadband providers must be involved.
- Power and backup: Which services need Uninterruptible Power Supply (UPS) and cellular failover.
- Security: Which devices need network access controls and monitoring.
- Costs: Which legacy rentals can be cancelled after migration.
Our relevant credentials are practical here: 3CX Platinum Partner for voice, Microsoft Gold Partner for Microsoft 365 and Azure, Cyber Essentials Plus certified for security, and controls mapped to International Organisation for Standardisation (ISO) 27001 and ISO 27018. Those matter because the work crosses more than one supplier box.
That leaves the common questions business owners ask before approving the work.
FAQs About the 2027 Landline Change
These answers cover three decision areas:
- Whether you can keep a landline-style service.
- What replaces the old network.
- What devices need checking before migration.
Can I Keep My Landline After 2027?
Yes, you can still have a landline-style service after 2027, but it won’t run on the old analogue network. Calls will be carried over digital technology, usually through broadband. If you rely on alarms, lifts or care devices, check compatibility before the old line is changed.
What is the 2027 Landline Switch Off?
The 2027 landline switch-off is the retirement of the United Kingdom’s old analogue copper network. The final deadline is January 31, 2027. After that, fixed calling moves to digital services that use an internet connection, such as Voice over Internet Protocol (VoIP).
What is Replacing the PSTN?
Digital calling over Internet Protocol (IP) is replacing the old network. For most organisations, that means Voice over Internet Protocol (VoIP), Digital Voice, a cloud-hosted service, or Session Initiation Protocol (SIP) trunking if an existing Private Branch Exchange (PBX) needs a short-term bridge.
What Happens When BT Stops Landlines?
When BT Group retires the old network, remaining analogue services will stop working or be moved by providers before the cut-off. Services that still depend on copper, including some alarms, lifts and older payment devices, may fail unless they are audited, replaced, or connected through a supported digital route.
Why is the PSTN Switch Off Happening?
It is happening because the copper network is old, harder to repair, and no longer fit for modern services. Parts and skills are becoming scarce. Ofcom recorded rising incident levels, and digital services offer clearer calls, better routing, and easier support when they are designed with backup power.
Talk to Microbyte about your landline migration from our Peterborough HQ, London, Woking or Lincoln teams. Send us your company name, telephone number and enquiry, and we’ll tell you what’s working, what isn’t, and what it will cost to fix it before January 31, 2027.
