The Last Copper Winter: A 2026 Migration Checklist for UK Firms Facing PSTN Retirement
Photo: Stephen Richards , CC BY-SA 2.0, via Wikimedia Commons
On 31 January 2027, the UK's public switched telephone network will reach the end of the road. For most businesses, the deadline has been visible for years. For many, it has still not been treated as a systems project. That is the risk. The retirement of PSTN is not simply a change of voice provider. It is the withdrawal of a copper service that a surprising range of business-critical equipment still relies on.
As of November 2026, the remaining window is short. Openreach's stop-sell milestone has already passed, and providers are working through migration queues. Firms that wait for a final notice may find that the notice arrives after the point at which a clean, tested cutover was still possible.
The deadline is not the only date that matters
The headline date is 31 January 2027. The practical date is earlier. It is the date by which your provider can survey the site, port numbers, supply an all-IP service and test the devices that sit behind it. For a single office with a handful of handsets, that may be weeks. For a firm with multiple sites, alarm panels, lift lines and legacy tills, it can be months.
Procurement teams should therefore treat the exercise as a business continuity project with a supplier dependency, not as a routine telecoms renewal. The question is not simply whether the monthly line rental can be replaced. It is whether every service that depends on a dial tone will still work when the copper circuit is withdrawn.
The hidden estate: what actually runs on a phone line
Most SMEs know about desk phones. Fewer have a complete picture of the other equipment attached to analogue lines. Common examples include intruder alarms and panic buttons, lift emergency lines, door-entry systems, fax machines, out-of-hours support lines, legacy EPOS terminals, CCTV dial-up links and modem-based monitoring equipment. Some of these devices are old enough that no one in the business now owns them.
That is why a line-by-line inventory is the first practical step. It should record the line number, location, supplier, contract end date, connected equipment and business owner. It should also note whether the line carries a broadband service, because a move to an all-IP service may change how connectivity is delivered as well as how calls are made.
A migration checklist for SMEs
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Inventory every line and device. Walk the sites, check comms rooms and ask facilities, security and retail teams what still uses a phone line. Do not rely solely on the telecoms bill.
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Name an internal owner. The project usually fails when responsibility is split between IT, facilities and finance. Give one person authority to chase suppliers and sign off testing.
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Ask each provider for an all-IP plan in writing. Confirm which services are being replaced, which are being retained and what happens to numbers, broadband and support arrangements.
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Test critical devices before cutover. Alarms, EPOS terminals and lift lines should be tested with the new service, not assumed to work because the handset does.
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Review alarm signalling. Many alarm panels need an IP or dual-path communicator. A voice call from an alarm panel over a VoIP service may not provide the reliability or line-seizure behaviour the panel expects.
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Check power and network resilience. VoIP depends on mains power and broadband. A simple power cut can remove both the phone system and the ability to call emergency services unless battery backup and a resilient network path are in place.
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Plan number porting early. Porting can be straightforward, but it can also stall if records do not match or if multiple providers are involved.
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Model the commercial change. Compare line rental, call packages, broadband, support and hardware refresh costs. The cheapest voice tariff is not necessarily the cheapest overall migration.
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Brief staff and customers. Update call scripts, voicemail messages, website contact details and internal guides. Test call quality and emergency calling arrangements.
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Keep a fallback plan. For the first weeks after cutover, retain a clear escalation route to the supplier and a documented process for reporting failed calls or devices.
Traps that catch firms out
One common mistake is assuming that any broadband connection will support voice well. VoIP is sensitive to congestion, poor upload speeds and weak Wi-Fi. Another is forgetting that analogue lines often provide power and line-seizure behaviour that digital services do not replicate in the same way.
Fax remains a stubborn issue. Some suppliers offer fax-over-IP, but reliability varies. Lift lines and alarm lines can be harder still, because they may be subject to building-management agreements or specialist maintenance contracts. Firms in leased offices should confirm who is responsible for the line and who will authorise the change.
A final trap is leaving number porting and device testing to the same week. If the port fails, or if an alarm panel cannot communicate, the business may be left with a working handset and a broken safety system. That is not a successful migration.
What good looks like
A well-run PSTN migration is unglamorous. It starts with a complete inventory, a named owner and a supplier conversation that covers every service on the line. It includes testing, documentation and a fallback plan. It treats the 31 January 2027 deadline as the end of a project that should already be under way, not as the start of one.
For UK firms still buying time, the remaining months are best spent on verification rather than reassurance. The copper network is leaving. The businesses that fare best will be those that know exactly what is attached to it.
