PSTN Switch-Off: What UK Businesses Need to Do Before January 2027
BT's Public Switched Telephone Network (PSTN) is being switched off permanently on 31 January 2027. Every UK business still using analogue phone lines, ISDN, or FTTC broadband delivered over copper must migrate to IP-based alternatives before that date. This guide explains what is changing, who is affected, and what you need to do.
The PSTN Switch-Off: Key Facts
BT is switching off the PSTN on 31 January 2027. All analogue phone lines and ISDN connections will stop working. 31% of UK businesses have already migrated to VoIP. Businesses still on ISDN or analogue lines — including those with alarm systems, lift phones, and payment terminals connected via phone line — must migrate before the deadline.
Explore business VoIP optionsWhat Is the PSTN Switch-Off?
The Public Switched Telephone Network (PSTN) is the analogue copper telephone infrastructure that has provided telephone services in the UK for over 100 years. BT Openreach is retiring this network permanently on 31 January 2027, replacing it with a fully digital, IP-based infrastructure. After this date, any device or system that relies on a traditional analogue or ISDN phone line will stop working.
BT has already stopped accepting new PSTN line orders in most exchange areas across the UK. Businesses in those areas can no longer order new analogue lines — the switch-off process has effectively already begun. The January 2027 date represents the point at which existing lines are terminated.
What Does the Switch-Off Mean in Practice?
Any business system that uses a traditional phone line must be migrated before 31 January 2027. This typically includes the main business phone system, but also devices and services that are easy to overlook:
- Fax machines connected via a phone line
- PDQ card payment terminals using a landline connection
- Fire alarms and intruder alarm systems with a dedicated phone line for monitoring
- Lift emergency telephones (required by law to provide an emergency call function)
- Door entry systems with phone line integration
- CCTV monitoring systems using a phone line for remote access
For many businesses, the main phone system is the most visible migration requirement. But failing to address alarm and safety systems before the deadline can create regulatory and safety issues.
Migrating Your Business Phone System to VoIP
The most common migration path for UK businesses is to move from an ISDN-connected PBX to a cloud-hosted VoIP or UCaaS (Unified Communications as a Service) system. Hosted VoIP delivers phone calls over your existing broadband or leased line connection, eliminating the need for ISDN entirely.
The benefits of migration extend beyond simply meeting the deadline. Modern VoIP systems include features that ISDN cannot provide: call management through a web interface, mobile apps for remote workers, Microsoft Teams integration, call recording, and auto-attendant features. Most UK businesses see a meaningful reduction in monthly telecoms costs after migration — removing ISDN line rental is often the single largest saving.
Key Considerations for UK Businesses
- Audit all phone lines before migrating: Identify every PSTN and ISDN line your business uses, including those connected to alarms, lifts, and payment systems — not just desk phones.
- Check your broadband connection: VoIP calls travel over your internet connection. If you are currently using FTTC broadband (which itself uses the copper PSTN network), you may also need to migrate to FTTP or a leased line to avoid losing broadband connectivity at the switch-off.
- Plan the migration well in advance: Migrating a phone system takes time — number porting, hardware changes, and staff training all need to be scheduled. Do not leave it until late 2026.
- Ensure emergency services access is maintained: Your new VoIP system must be configured to provide access to 999 with location information, as required by Ofcom regulations.
How AMVIA Can Help
AMVIA manages PSTN switch-off migrations for UK businesses — from auditing your current lines and systems, to recommending the right VoIP solution, porting your existing numbers, and configuring the new system. AMVIA also handles the connectivity side, ensuring your broadband or leased line is ready to support VoIP calls before ISDN is removed. Call 0333 733 8050 to start your migration assessment today.
Who Is Affected by the PSTN Switch-Off?
The switch-off affects any business or service connected via the traditional copper telephone network.
Analogue Phone Lines
Standard PSTN lines used for voice calls, including fax machines and PDQ card terminals connected via phone line.
ISDN2 and ISDN30
Digital lines used by PBX phone systems — widely deployed in UK offices with 10 or more phone extensions.
Alarm and Lift Lines
Fire alarms, intruder alarms, and lift emergency telephones often use dedicated PSTN lines that will stop working.
PDQ and Payment Terminals
Card payment terminals and EPOS systems using a phone line connection require migration to IP or 4G.
PSTN Switch-Off Action Checklist
Steps every business should complete before the January 2027 deadline.
Audit all PSTN and ISDN lines
Identify every phone line in use — including alarms, lifts, payment terminals, and fax machines.
Check broadband connectivity
Confirm whether your broadband will be affected and whether migration to FTTP is needed.
Choose a VoIP replacement system
Select a hosted VoIP or UCaaS solution appropriate for your team size and requirements.
Plan number porting
Arrange transfer of existing geographic numbers to your new VoIP provider — allow 2 weeks.
Migrate non-telephony PSTN services
Alarms, lift phones, and payment terminals migrated to IP or 4G alternatives before the deadline.
Train staff on new system
Staff comfortable with new handsets, apps, and call management features before go-live.
PSTN Switch-Off FAQs
Your analogue and ISDN phone lines will stop working. Incoming and outgoing calls on those lines will be impossible. Any connected services — alarms, payment terminals, lift phones — will also fail. There is no indication that BT will offer extensions. Businesses should plan and begin migration well in advance of the deadline, particularly as demand for VoIP installation will increase significantly as the date approaches.
FTTC broadband (the most common business broadband type) uses the copper PSTN network for the section from the street cabinet to your premises. Where your broadband line is delivered over PSTN copper, BT is migrating this service to an all-IP WLR (Wholesale Line Rental) replacement. In most cases, broadband will continue — but if you are on an older FTTC product, check with your provider that your service will be migrated and not simply terminated. AMVIA can check your current connectivity position as part of a pre-migration assessment.
Yes. Number porting allows you to transfer your existing geographic phone numbers to a new VoIP provider. The porting process typically takes 7 to 14 working days. AMVIA manages number ports as part of its VoIP migration service — you keep your existing numbers and your clients experience no change in how they contact you.
Migration costs vary depending on the number of lines, the complexity of your existing phone system, and whether new handsets are required. Many businesses find the ongoing cost of VoIP lower than their current ISDN line rental — removing multiple ISDN channels can save hundreds of pounds per month. AMVIA provides a fixed-price migration quote after assessing your current setup, so there are no unexpected costs.
Don't Leave Your PSTN Migration Too Late
AMVIA will audit your current PSTN and ISDN lines, identify all affected systems, and manage your migration to VoIP before the January 2027 deadline.
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