The Big Switch Off deadline is 31 January 2027
The UK’s PSTN, ISDN, ADSL and related Wholesale Line Rental services are moving to fully digital, IP-based alternatives.
Businesses should audit every phone line and connected device now—migration is staged, but 31 January 2027 remains the firm retirement deadline.
What is the Big Switch Off?
The Big Switch Off is the retirement of the UK’s ageing analogue telephone network. The PSTN has supported traditional landlines for decades, while ISDN added digital services over the same legacy infrastructure. Calls and related services are moving to modern IP technology, including Voice over Internet Protocol (VoIP).
Essential facts
- Deadline: 31 January 2027
- Affected: PSTN, ISDN, ADSL and related Wholesale Line Rental products
- Replacement: Fully digital services using Internet Protocol
- Stop sell: Normal new orders for traditional Openreach WLR services have ended
Which business services could be affected?
Audit traditional phone and broadband lines, lift emergency lines, alarms, door entry, telecare and lone-worker devices, fax machines, analogue modems, CCTV, payment terminals, gates and intercoms. Confirm compatibility with each equipment provider rather than relying on the telephone plug alone.
What should businesses do now?
- Build an inventory of every number, line, circuit and connected device.
- Identify dependencies with alarm, lift, CCTV, payment and equipment providers.
- Check connectivity and capacity at every site.
- Choose a digital phone service and confirm number-porting requirements.
- Plan resilience: digital phones need local power and connectivity, so consider battery backup, UPS capacity, secondary broadband and mobile failover.
- Test before retirement including calls, routing, emergency procedures and connected devices.
- Train the team on new handsets, apps and outage procedures.
Which replacement phone system should you choose?
Most businesses choose either a hosted cloud phone system or an on-premises IP system.
A hosted or cloud phone system is managed by a service provider and accessed through an internet connection. It usually requires less equipment on site and can connect desk phones, computers and mobile devices.
An on-premises IP system keeps more hardware and management within the business. It can suit organisations with specific control, integration or security requirements, although they must manage maintenance, updates, resilience and specialist support.
The right choice depends on connectivity, compliance, existing equipment, workforce location and the organisation’s appetite for managing infrastructure.
Big Switch Off FAQs
When is the PSTN switch off?
BT plans to retire the PSTN and related analogue services by 31 January 2027. Complete migrations and testing before that date.
Will every line stop on the same day?
Providers are migrating customers in stages, so individual services may move earlier. However, 31 January 2027 is the firm retirement deadline.
Can businesses still order a new analogue landline?
The nationwide Openreach stop sell means normal new orders for traditional WLR, PSTN or ISDN products have ended.
Will VoIP work during a power cut?
Not without power for the router, network equipment and handset. Assess battery backup, UPS capacity, mobile alternatives and failover connectivity.
Can existing phone numbers be kept?
In most migrations, numbers can be ported. Confirm ownership, porting requirements and timescales early.
What happens if a business does nothing?
Services may stop working, be moved to a basic interim service or lose features. Connected devices may also fail.
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