Key takeaways
The PSTN (Public Switched Telephone Network) -- the UK's traditional copper-wire telephone network -- is being retired. BT has set a deadline of January 2027 to switch off its PSTN, with other providers using BT's network following the same timescale.
After the PSTN is retired, all landline calls will be delivered over VoIP (Voice over Internet Protocol) -- digital voice technology that runs over a broadband connection.
Most customers will notice little practical difference. Your phone will work the same way, with the same number, but plugged into a router rather than a wall phone socket.
Customers with telecare devices, burglar alarms, fax machines or card payment terminals connected to a landline line need to check compatibility with their device supplier before the switch-off.
Ofcom requires providers to give customers at least 40 days notice before migrating them to VoIP, and to make extra provision for vulnerable customers who depend on their landline.
Reviewed: June 2026Key facts
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What is the PSTN and why is it being switched off
The PSTN (Public Switched Telephone Network) is the traditional telephone network that has carried landline calls in the UK for over a century. It uses copper wire infrastructure, physical telephone exchanges and analogue or digital signal technology developed in the 1980s. The network is ageing, increasingly expensive to maintain, and incompatible with modern communications infrastructure being built across the country.
At the same time, the UK's broadband network is being upgraded to full-fibre (FTTP -- Fibre to the Premises) technology. Full-fibre infrastructure does not support traditional PSTN telephone services. Rather than maintain two separate networks, providers are consolidating telephone calls onto the broadband network using VoIP technology.
The January 2027 deadline
BT, which operates the largest portion of the UK's PSTN infrastructure, announced it would retire its PSTN by January 2027. Because many other providers (Sky, TalkTalk, EE, Plusnet and others) use BT's Openreach network to deliver their landline services, they are following the same timescale. Virgin Media operates its own separate cable network and is managing its own PSTN retirement on a broadly similar schedule.
Ofcom sent a letter to industry in January 2026 setting out expectations for how providers should migrate customers safely ahead of the deadline.
What changes for customers
For most customers, the practical experience of making and receiving calls will not change. Your phone number stays the same. You will still dial the same way. Call quality on VoIP is typically equal to or better than PSTN.
The main physical change: your telephone handset will plug into a socket on your broadband router rather than into the phone socket on your wall. Your provider will supply any necessary new equipment -- a new router, an adapter or in some cases a new phone handset -- at no charge.
Calls over VoIP travel as data packets over your broadband connection. As long as your broadband is working, your VoIP landline works. If your broadband goes down, your landline goes down too -- unlike PSTN landlines which were independent of broadband.
Power cuts and emergency calls
Traditional PSTN landlines continued to work during power cuts because the copper telephone network carried its own low-voltage power. VoIP phones depend on your broadband router, which requires mains electricity.
Ofcom requires providers to offer battery backup solutions to customers who identify as needing their landline during a power cut -- for example elderly customers, those with medical needs or customers in areas with poor mobile coverage. If this applies to you, contact your provider before the migration to arrange battery backup.
All VoIP services in the UK are required to provide access to emergency services (999 and 112) even without a power source in most circumstances, though the specific implementation varies by provider. Confirm your provider's emergency call arrangements before the PSTN migration completes.
Devices affected by the switch-off
| Device type | Affected? | Action required |
|---|---|---|
| Standard telephone handset | Yes | Will need to plug into router -- provider will advise |
| Telecare / lifeline alarm | Possibly | Contact device supplier to check VoIP compatibility |
| Burglar alarm via phone line | Possibly | Contact alarm company to check VoIP compatibility |
| Fax machine | Possibly | Most fax machines do not work over VoIP -- consider alternatives |
| Card payment terminal | Possibly | Contact payment terminal provider to check compatibility |
| Home CCTV via phone line | Possibly | Contact CCTV supplier to check compatibility |
| Standard mobile phone | No | Not affected by PSTN switch-off |
| Broadband-only service | No | Already on digital -- not affected |
What providers must do before migrating you
Ofcom requires providers to give customers at least 40 days notice before migrating them from PSTN to VoIP. The notice must explain what is changing, what action (if any) the customer needs to take, and what equipment the provider will supply. Providers must not migrate vulnerable customers -- including those who depend on a landline for medical equipment, telecare or emergency contact -- without first assessing their needs and arranging appropriate support.
Related guides
Disclaimer: This guide is for informational purposes only. Kael Tripton Ltd is not regulated by the FCA and does not provide financial advice. Telecoms information is sourced from Ofcom, the UK communications regulator. Always verify current information at ofcom.org.uk.
Frequently asked questions
When is the PSTN being switched off in the UK?
BT has set a deadline of January 2027 to retire its PSTN. Other providers using BT's Openreach network are following the same timescale. Virgin Media is retiring its own cable-based network on a broadly similar schedule. The migration of individual customers is happening progressively from now until the deadline.
What is replacing the PSTN?
VoIP (Voice over Internet Protocol), also called digital voice or digital phone. VoIP delivers telephone calls as data packets over a broadband connection rather than over copper telephone wires. Your phone number stays the same and the experience of making calls is largely unchanged.
Do I need to do anything before the PSTN switch-off?
Your provider will contact you before migrating your service. They will supply any necessary new equipment at no charge. If you use a telecare device, burglar alarm, fax machine or card payment terminal connected to your landline, contact the device supplier to check VoIP compatibility before your migration date.
Will my landline work in a power cut after the PSTN switch-off?
Not unless your provider has supplied battery backup equipment. Traditional PSTN landlines worked during power cuts because they carried their own power. VoIP phones require your broadband router to work, which needs mains electricity. If you need your landline to work during power cuts, contact your provider to request battery backup before the migration.
Will my phone number change when I move to VoIP?
No. Your existing landline number is preserved when migrating to VoIP. Number porting rules under Ofcom's General Conditions ensure your number stays with you through the technology transition.
What if I do not have broadband?
After the PSTN switch-off, maintaining a landline will require a broadband connection (since VoIP runs over broadband). If you currently have a standalone landline without broadband, your provider will need to arrange a broadband connection as part of the migration, or you will lose landline service. Ofcom requires providers to manage this transition fairly for customers without broadband.
How much notice will I get before being switched to VoIP?
Ofcom requires providers to give customers at least 40 days notice before migrating them from PSTN to VoIP. The notice must explain what is changing and what equipment will be supplied. Vulnerable customers must receive additional support before migration.
Can I refuse to move to VoIP?
The PSTN switch-off is a network-level change driven by infrastructure retirement. Providers will migrate all customers as part of the switch-off process. However, Ofcom requires providers to handle vulnerable customers with particular care and to ensure no customer is migrated in a way that leaves them without adequate telephone service.
