What happens if a business has not moved from PSTN before 31 January 2027?

The outcome depends on the provider and service. BT Business says some eligible services may receive a basic voice-only protective migration, while ISDN, Featureline, multiline and certain broadband services cannot be moved automatically and could stop working. Businesses should confirm the plan for every service with their current provider.

Will a business be moved automatically to a digital phone service?

Do not assume so. Automatic or protective migration is provider- and service-specific, may provide only limited functionality, and does not prove that connected equipment will work.

Can a business keep its existing telephone number?

A number can often be retained, but the receiving provider must confirm eligibility and the transfer process. Do not cancel the old service before the number transfer is confirmed.

Updated 5 October 2026

What happens if your business has not switched its landline by 2027?

Users of the Openreach public switched telephone network must be moved to replacement services by 31 January 2027. The deadline affects more than voice calls: traditional lines can also carry ISDN, ADSL broadband, alarms, lifts, payment equipment and other services.

Do not assume an automatic move will solve the problem. Ask your current provider to identify every service, say whether it can be migrated, and confirm exactly what will work afterwards.

What may happen if you do nothing?

The answer depends on the network, provider and service. BT Business currently describes a “Protective Migrations” programme for some of its remaining customers, but says the resulting service may provide only basic voice functionality. That is not the same as a planned business phone replacement.

Existing service	Current BT Business position	What the business should do
Eligible traditional single line	It may receive a protective migration to a basic IP service. Contract terms may change.	Obtain the migration date, features, equipment, price and continuity arrangements in writing.
ISDN, Featureline, multiline or certain broadband access	BT says these cannot be moved automatically through its protective programme and could stop working from 31 January 2027.	Order a suitable replacement rather than waiting for an automatic move.
Alarm, lift, CCTV, EPOS, door entry or fax	A voice migration does not confirm that the connected device is compatible.	Have the device supplier specify and test its replacement connection before the old line ends.
ADSL or broadband sharing an old line	Broadband that relies on the traditional network may also need upgrading.	Coordinate the broadband, number and voice orders so one change does not unexpectedly cease another service.

Protective migration is a BT Business process, not a universal promise. Customers of other providers should ask their current provider for its own migration plan.

How to find every affected service

Start with invoices and provider portals, but also inspect the premises. A line that appears to be unused may terminate in a plant room, alarm panel, lift controller or older payment device. Record the provider, account reference, telephone number, service type, location and business owner for each connection.

Telephone lines, DDI ranges, switchboards, ISDN2/ISDN30 and Featureline.
ADSL, routers and any broadband billed with the phone service.
Security, fire, care and environmental alarms.
Lift phones, gates, intercoms, door entry and CCTV monitoring.
Fax, franking, vending, EPOS and card-payment equipment.

A practical action plan

Inventory: list every line, number, device and account, including services at quiet or unmanned sites.
Confirm: ask the current provider which services depend on PSTN, WLR, ISDN or ADSL and what it proposes to do.
Separate dependencies: identify broadband, numbers and equipment that share the same line or account.
Design the replacement: specify users, simultaneous calls, queues, mobile apps, desk phones, voicemail and reporting.
Plan resilience: decide how calls and critical devices work during a power, broadband or provider failure.
Test before cease: prove inbound and outbound calling, number presentation, diversions and every connected device.

Build an equipment action list

Will you lose the number?

Moving to a digital service does not automatically mean changing your number. However, number transfers must be planned. Never cancel the old service until the receiving provider has confirmed that the number is portable, accepted the request and explained what else will cease.

What happens during a power or broadband failure?

A traditional line could carry its own power. A digital telephone normally relies on the broadband connection, router, network equipment, phone hardware and mains electricity. A mobile-data backup does not solve a power cut unless the required equipment also has power, and it is not a proven fallback until signal and automatic failover have been tested at the premises.

Questions to ask before signing

Which existing services will you replace, transfer or cease?
Can you retain every number and DDI range, and what is the port sequence?
How many simultaneous calls are included?
Which routers, adaptors, handsets and licences are required?
What works during a broadband, power or provider failure?
What are the setup, porting, monthly, usage, equipment and exit costs?
Can the numbers and purchased equipment move to another provider later?

A service to include in your comparison

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View SOHO66 business phone options

Primary sources

GOV.UK: Telecommunications Modernisation Connectivity Timeline, published 24 March 2026.
BT Business: The PSTN, ISDN and ADSL switch-off, including protective migrations and services that cannot be moved automatically.
Ofcom: Your landline is going digital, updated 26 August 2026.
Openreach: Time for a “big switch-up” as PSTN switch-off looms, published 5 February 2026.

General information only. Migration, compatibility and porting depend on the exact network, provider, account and equipment. Obtain written confirmation before changing or cancelling an existing service.