The UK’s traditional copper-based phone network, the Public Switched Telephone Network (PSTN), will be permanently switched off on 31 January 2027.
This change affects BT landlines, ISDN2 and ISDN30 circuits, phone-line-based alarm systems, ADSL broadband, FTTC broadband and many business phone systems. The change applies across the UK except for the Isle of Man, Guernsey, Jersey and the KCOM network in Hull.
All UK PSTN-based services will stop working on 31 January 2027.
However, disruption begins earlier. In most areas, Openreach has implemented a stop-sell, which increasingly prevents customers from ordering or modifying copper-based services. This forces a gradual migration from copper to fibre as residents and businesses move.
This guide explains exactly what will happen, when it will happen, and how it affects homes and businesses.
What Is the PSTN Switch-Off?
The PSTN switch-off is Openreach’s permanent retirement of the UK’s copper phone network that carries traditional landline and ISDN services.
The PSTN switch-off ends the following services:
- Analogue phone lines
- ISDN2 and ISDN30
- ADSL (Asynchronous Digital Subscriber Line) broadband that requires a BT phone line
- FTTC (Fibre to the Cabinet) broadband that requires a BT phone line
These services are being replaced by full fibre (FTTP) where available, SOGEA (FTTC without a phone line) where FTTP is not available, and IP-based voice (VoIP).
PSTN Switch-Off Timeline (UK)
| Date | What Happens |
|---|---|
| September 2023 | Nationwide stop-sell begins for new PSTN lines and Wholesale Line Rental |
| 2023–2027 | As telephone exchanges reach around 75% FTTP availability, a stop-sell is placed on new ADSL and FTTC orders to premises where FTTP is available |
| 31 January 2027 | PSTN, ISDN and copper phone line services stop working |
Openreach’s stop-sell on new ADSL / FTTC connections takes effect after 12 months notice.
By mid February 2026, Openreach’s stop-sell on FTTC and ADSL applies to 1281 telephone exchanges covering 12.5 million premises. This covers 51% of the Openreach FTTP footprint.
Will The UK PSTN Switch Off Be Delayed?
Any further delay would be decided by Openreach before January 2027. The switch off has already been delayed once (from December 2025 to January 2027) to give communication providers more time to identify vulnerable users and safely migrate them to IP-based alternatives.
Extensive work is underway to minimise the need for further delays. Over 4000 telecoms engineers are working with 40 telecare providers to safely migrate telecare users to IP-based alternatives, one home at a time, at scale.
The first delay to PSTN switch off was announced in May 2024, 19 months before the original switch off date December 2025. As of January 2026, Openreach has not announced any further delay to the PSTN switch-off. This shows the PSTN switch off is now far closer to happening on schedule.
The PSTN switch off date remains Openreach’s decision. However, Openreach is subject to regulatory oversight (Ofcom), Governmental oversight (DSIT) and parliamentary scrutiny. These interested parties remain focused on protecting vulnerable users, such as elderly people with alarm pendants, and rural users that cannot rely on mobile coverage. Any further delay to PSTN switch off would likely be extremely limited and focused on protecting these vulnerable groups. There is no guarantee that there will be a further delay.
Which UK Telecom Services Are Affected by the PSTN Switch-Off?
The UK PSTN switch-off impacts:
- BT phone lines
- ADSL broadband on BT landlines
- FTTC broadband
- ISDN2 and ISDN30
- Fax lines
- Alarm systems
- Lift phones and emergency call buttons
- G.fast broadband
Any of these services that rely on copper phone lines will stop working.
Many homes and businesses will only discover the impact when they wake up on 1 February 2027 to find their FTTC connection is down and their landline has no dial tone.
What Happens to Standard Landlines?
Analogue BT phone lines will stop working by 31 January 2027.
They are being replaced by VoIP (Voice over IP) services that run over broadband.
To keep a phone service, you will need:
- A broadband connection (FTTP, SOGEA, SOGFAST or SOTAP)
- A VoIP service (often called “Digital Voice” or “IP Voice”)
- A VoIP phone or adapter
Your existing phone number can usually be transferred to the replacement VoIP service.
If you need your phone to work during power cuts, you will need a battery backup unit for both the fibre equipment and router.
If your premises can order FTTP, slower broadband connection options may not be available to you.
What Happens to ADSL Broadband?
ADSL delivered over a standard BT phone line is being withdrawn everywhere by 31st January 2027.
If this affects you, you will need to migrate to:
- FTTP (Full fibre without a phone line)
- SOGEA (FTTC without a phone line)
- SOGFAST (G.Fast without a phone line)
- SOTAP (ADSL without a phone line)
You can only order SOTAP if faster options aren’t available.
If your existing ADSL connection is provided by a local loop unbundler such as TalkTalk, it may be able to continue providing ADSL services temporarily. The PSTN switchover affects ADSL provided over BT phone lines (provisioned over ‘shared metallic path facility’). The switch off does not yet affect existing services provided over a non-shared metallic path facility i.e. where the physical line doesn’t plug into BT’s equipment.
However, this is a temporary reprieve. Openreach will decommission 4600 of its 5600 telephone exchanges, forcing local loop unbundlers to remove their equipment used for powering ADSL services. Local loop providers may retire ADSL services nationwide pre-emptively as a consequence, to simplify their support, engineering and on-boarding processes.
What Happens to FTTC Broadband?
Most FTTC (Fibre to the Cabinet) connections are provided using a BT phone line.
The PSTN switch off will result in your FTTC connection ceasing to work. You will need to switch to an alternative such as:
- FTTP (Fibre To The Premise)
- SOGEA (Single Order Generic Ethernet Access)
SOGEA provides FTTC broadband over the Openreach network without a traditional phone line.
New orders of SOGEA are gradually being phased out. When 75% of premises served by a given telephone exchange can get FTTP, Openreach stops allowing those premises to order SOGEA rather than FTTP. SOGEA remains available to those premises which cannot get Openreach FTTP.
What Happens to ISDN2 and ISDN30?
UK ISDN services will be permanently switched off in January 2027.
New ISDN orders ended in September 2023.
Businesses must switch to using:
- A Hosted Telephony or
- SIP Trunks
Calls will run over a data connection instead – typically, an internet connection.
Businesses can continue to use their existing on-site PBX to power their phone system, but they will need to add a SIP gateway if their old PBX does not support SIP innately.
What Happens to Alarm Systems?
Burglar alarms, lift alarms and medical pendants that use phone lines will stop working.
They must be replaced with IP-based alarm systems that run over broadband and include local battery backup to meet UK telecare safety requirements.
Contact your alarm provider to check that your alarms will still work after PSTN switch off.
Switching from the PSTN to IP-based alternatives almost always requires an engineer visit. There will be a spike in demand for such visits immediately prior to and after the PSTN switch-off date. It is extremely risky to leave migration to the last minute.
What Happens to Fax Machines?
Fax machines will need to transmit their data over VoIP services, because traditional landlines will be retired as part of the PSTN switch off. Poor underlying network quality may cause synchronisation issues. It may become harder to send long faxes.
Businesses should move to modern alternatives such as digitally signed email or electronic document signing services (such as Docusign).
The UK Universal Service Obligation (USO) was amended in September 2022, removing the need for BT and KCOM to provide fax services. This took effect in January 2023 when OFCOM updated its Broadband/Telephony Universal Service Conditions.
These changes do not preclude telecoms firms offering fax services. However, they foreshadow a move to such services being provided on a ‘best efforts’ basis.
Why Is the PSTN Being Switched Off?
The copper network is:
- Expensive to run
- Energy inefficient
- Fault-prone
- Unable to support modern speeds
By switching to fibre and IP voice:
- Openreach can close 4,600 of 5,600 telephone exchanges
- Maintenance costs will fall
- Connection speeds will rise
- Connections will be more reliable
- Call quality can improve
Will Everyone Be Forced onto Full Fibre?
Yes, eventually. But not in January 2027.
The PSTN switch off eliminates most connections that require a physical connection to a particular telephone exchange.
When Openreach FTTP reaches 75% availability in an exchange area, Openreach can require remaining copper customers to migrate to full fibre.
This will result in faster, cheaper, more reliable, more easily upgraded telecoms – which is in everyone’s interests.
It is very common for legacy technology to be retired while still working in order to simplify ongoing support.
What UK Businesses and Homeowners Should Do Now
If you use:
- A BT Landline
- ADSL on a BT landline
- FTTC
- ISDN
- Alarm lines
You should talk to a communications provider about migrating to:
- FTTP or SOGEA
- Hosted VoIP / SIP trunking
- IP-based alarm systems
Waiting until 2027 risks losing service with no replacement.
What will Syntura Do About PSTN Switch Off?
We will be contacting all affected Syntura customers to arrange the necessary service migrations from BT landlines, ADSL connections, FTTC connections and ISDN lines.
As a UK managed services provider, Syntura provides leased lines, FTTP connections and VoIP services, allowing firms to communicate after the PSTN switch off.
What Will Be the Long-Term Impact of the UK PSTN Switch Off?
The PSTN switch-off is a preliminary step that will allow Openreach to close approximately 4,600 of its 5,600 UK telephone exchanges, dramatically reducing the cost of operating the national telecoms network.
Openreach’s prices are strongly regulated by OFCOM, so much of this cost saving will be passed through to communications providers, who will in turn pass it on to telecoms users, in the form of lower costs and faster, more reliable fibre-based connections.
VoIP calls have been cheaper than identical calls made over PSTN and ISDN lines. The retirement of PSTN lines and ISDN lines will force users who have been overpaying for calls to switch to services that are cheaper to deliver. As in the mobile market, this is likely to lead to the widespread use of generous call bundles.
In mobile networks, VoIP enables wideband audio codecs that significantly improve call quality, and this same improvement will eventually come to UK landline replacements.
Many residential phone services will offer smartphone apps that let subscribers make and receive calls via an app on their mobile. These are likely to incorporate instant messaging features.
Copper from legacy phone systems will be recycled, making its way into electric vehicles and data centres. Telecoms duct space will eventually be freed up for use by fibre-optic network operators.
Those on full-fibre connections will see significant rises in downstream and upstream connection speeds, as fibre-optic cabling is capable of far higher speeds over long distances than copper-based lines. This will enable higher-resolution video, including for television consumption, social media streaming, file syncing to the cloud, and telemedicine.
PSTN Switch-Off Summary (UK, 2027)
The UK is permanently moving from copper phone lines to fibre-optic based alternatives and VoIP.
By January 2027, all PSTN-based services will stop working. This includes BT landlines, ADSL, FTTC, ISDN, fax lines and phone-line-based alarm systems.
This affects millions of homes and businesses — but fibre and VoIP provide faster, cheaper, more reliable services.
Early migration avoids disruption to service and long waits for an engineer appointment.
Last updated: January 2026 (UK PSTN switch-off guidance)