The UK’s legacy copper-based phone network is being retired. By 31 January 2027, all Public Switched Telephone Network (PSTN) and ISDN services will be permanently switched off.
According to the UK Government guidance on moving landlines to digital technology, this transition is part of a nationwide shift to modern digital infrastructure.
For many organisations, this is being positioned as a telecoms upgrade. In reality, it is a business-wide change that impacts far more than voice.
What The PSTN Switch-Off Actually Means
Openreach is closing the UK’s copper voice infrastructure, replacing it with All-IP services delivered over modern connectivity. You can learn more via the Openreach digital phone lines programme.
Key milestones you need to be aware of:
- No new analogue lines have been available since September 2023
- The full switch-off happens on 31 January 2027
- Any service still relying on copper will stop working immediately
The replacement model is straightforward in principle. Voice moves to VoIP, SIP or cloud calling, delivered over fibre broadband, leased lines or mobile data.
Why This Is Not Just About Phones
Voice is only the visible layer. Many critical systems still rely on the same copper lines.
This includes:
- Alarm systems, lifts and emergency phones
- Door entry, intercoms and CCTV monitoring
- Card payment terminals using dial-up
- Telecare and safeguarding services
- Legacy broadband connections such as ADSL
- Fax, telemetry and other machine-to-machine services
This broader impact is reflected in the Ofcom Connected Nations 2024 report, which highlights growing reliability challenges in legacy infrastructure.
Who Is Most Exposed
Some sectors face greater complexity and risk due to scale or regulatory requirements.
The organisations most affected typically include:
- Multi-site retail and hospitality with large estates of payment terminals and alarm lines
- Property and facilities teams managing lifts, fire panels and shared infrastructure
- Healthcare and social care environments where telecare services are critical
- Manufacturing and logistics sites with telemetry and depot communications
- Public sector and education estates with campus-wide infrastructure
- Businesses still running legacy PBX systems with limited internal telecoms expertise
For these organisations, this is not a single migration. It is a coordinated transformation across multiple systems.
The Cost Of Waiting
Delaying action increases both operational and financial risk.
There are four realities businesses need to factor in:
Any remaining PSTN lines will stop working immediately after the switch-off date.
Critical systems such as lift emergency lines and fire alarms are regulated. Failure to migrate creates duty-of-care risks.
As 2027 approaches, engineer availability and porting capacity will tighten. Late-stage migrations are likely to become more complex and more costly.
Legacy network reliability is already declining, with regulators highlighting increased failure rates in ageing infrastructure.
A Better Way To Approach The Migration
The most successful PSTN programmes are not treated as line-by-line replacements. They are treated as an opportunity to modernise communications.
A structured approach typically includes:
Audit every line, device and dependency across your organisation.
Ensure your connectivity can support IP voice reliably, whether through fibre, leased lines or SD-WAN.
Move to cloud calling or SIP-based solutions aligned to how your teams actually work.
Plan migration phases carefully, with number porting, user adoption and ongoing support built in.
Start With A PSTN Readiness Review
Before making any technology decisions, you need a clear view of your current estate.
A readiness review gives you:
- A full inventory of lines, devices and dependencies
- A target architecture for voice and connectivity
- A phased migration roadmap with costs and risks
- A clear number porting strategy
Without this, organisations often underestimate the scope of change and face avoidable disruption.
The PSTN switch-off is fixed and fast approaching.
The organisations that act early will reduce risk and use the transition to their advantage. Those that delay will be forced into reactive decisions under pressure.