The PSTN switch-off in January 2027: a guide for Cardiff businesses that use BT's network have to follow the same timescale.
Calls will instead run over internet technology: VoIP (Voice over Internet Protocol), digital voice, or all-IP phone services (https://www.gov.uk/guidance/moving-landlines-to-digital-technologies).
When is the PSTN switch-off?
All users of the Openreach PSTN need to be migrated to new services by 31 January 2027 (https://www.gov.uk/guidance/telecommunications-modernisation-connectivity-timeline). Openreach says the deadline is locked and there's no extension (https://www.openreach.com/news/time-for-a-big-switch-up-as-pstn-switch-off-looms/).
Openreach has also warned that businesses which don't migrate will face higher charges before losing service altogether.
What happens if you don't switch?
Openreach says that after 31 January 2027, a business still using services over the traditional network may be moved onto an emergency voice-only service, or may lose its service altogether (https://www.openreach.com/big-switch-off/digital-phonelines-for-businesses). BT Business adds that services such as ISDN, Featureline and multiline can't be moved automatically and will stop working if they haven't been moved (https://business.bt.com/help/article/phone-line-and-services/move-from-traditional-lines-to-the-cloud/the-pstn-and-isdn-switch-off-what-it-means-for-you/).
In short: waiting means losing control of the timing, your options and possibly your service.
What's affected? (It's more than your phones)
GOV.UK lists devices and systems that can rely on the old network, including analogue phones, fire and other alarms, payment terminals, lifts, intercoms and broadband services. Openreach also mentions CCTV and door entry systems.
Walk round your premises and check for:
- Phone lines and ISDN: main numbers, fax lines and any extra lines.
- Phone systems: older on-site systems connected to ISDN or analogue lines.
- Alarms: intruder alarms, fire alarms and lift emergency lines that dial out.
- Card machines: older payment terminals that use a phone line.
- Door entry and intercoms.
- Franking machines, fax machines and other equipment plugged into a phone socket.
- Broadband: copper-line services including ISDN, ADSL and FTTC may also be affected.
For every item, ask the supplier whether it works on a digital line, needs an adaptor, or needs replacing.
What replaces your landline?
For most businesses, the replacement is a cloud (VoIP) phone system. Calls run over your internet connection, and you can use desk phones, mobile and desktop apps, or both. See what a cloud phone system is and how it works: /what-is-a-cloud-based-phone-system.
A modern system usually does more than the old one: auto-attendant, call recording, voicemail to email, working from home on the business number, and Microsoft Teams integration.
Can you keep your phone number?
Usually, yes. Numbers, including local 029 numbers, are moved across by porting. It takes some lead time, which is another reason not to leave it late.
What about power cuts?
Digital lines need mains power and won't work in a power cut without a battery or other backup. For most businesses, the practical answer is to divert calls to mobiles automatically, and to put the router on a small battery backup if the phones are critical.
Your switch-off checklist
Openreach recommends review, test, switch. In practice:
1. Review: list every number, line and device that uses a phone line. Find your current contracts and end dates.
2. Check your connection: make sure your business broadband (/broadband) or leased line (/leased-lines) can carry calls, and decide whether you need a backup.
3. Test: ask suppliers of alarms, card machines and lifts to confirm they work on a digital line.
4. Choose your phone system: decide on handsets, apps and call flows.
5. Switch: port your numbers, install the new system, train the team, then cancel the old lines.
If you have several sites or a lot of connected equipment, start now. Planning takes longer than the switch itself.
Switching in Cardiff and South Wales
Local knowledge helps. Older buildings in the city centre and Cardiff Bay often have mixed cabling and awkward Wi-Fi, and both affect call quality. A provider who will visit, check the data cabling (/data-cabling) and Wi-Fi (/wifi), and stay for support usually makes for a smoother switch than an online-only setup.
For the practical steps, see our guide on how to switch from landline to VoIP: /how-to-switch-from-landline-to-voip-a-practical-guide-for-businesses.
Frequently asked questions
When is the PSTN switch-off?
Traditional phone lines on the Openreach network need to move to a digital service by 31 January 2027.
Will the deadline be extended?
Openreach has said the deadline is locked and there's no extension.
Does the switch-off affect my broadband?
It can. Broadband that runs over copper lines, including ADSL and FTTC, is affected.
Can I keep my business phone number?
Usually, yes. Your number can be ported to your new digital phone system.
Will my alarm or card machine still work?
Not necessarily. Check every device that uses a phone line with its supplier before you switch.
Is the switch-off happening everywhere at once?
Providers are moving customers in phases, but the final Openreach date is 31 January 2027. Contact your provider to find out your timeline.
Get a free line check
Not sure what you've got or what needs to change? Crystal Voice Data is a Cardiff-based Gamma Accredited Partner and O2 Business Partner. We'll review your lines, numbers and connected equipment, and plan a move to a business phone system (/office-phones) that keeps your 029 number. Book a free line check (/contact-us) or call 0333 5678 444, Monday to Friday, 9am to 5pm.
The UK's old copper telephone network is being switched off. If your business still uses traditional phone lines, or anything that plugs into one, you need to move to a digital service before 31 January 2027. This guide explains what's happening, what's affected, and what to do next, in plain English.
What is the PSTN, and why is it being switched off?
The PSTN (Public Switched Telephone Network) is the copper network that has carried landline calls for decades. ISDN, the digital line service many businesses use for multiple lines, runs over the same old infrastructure. The decision to retire it was made by the telecoms industry because the network is old and increasingly expensive to maintain. Calls will instead run over internet technology: VoIP, digital voice, or all-IP phone services.
When is the PSTN switch-off?
All users of the Openreach PSTN need to be migrated to new services by 31 January 2027. The deadline is locked and there is no extension. Businesses that do not migrate may face higher charges before losing service altogether.
What happens if you do not switch?
A business still using the traditional network may be moved onto an emergency voice-only service or may lose service altogether. Services such as ISDN, Featureline and multiline cannot be moved automatically and will stop working if they have not been moved. Waiting means losing control of the timing, your options and possibly your service.
What's affected? (It's more than your phones)
Check phone lines and ISDN, older phone systems, intruder and fire alarms, lift emergency lines, card machines, door entry and intercoms, fax and franking machines, and broadband that depends on copper lines such as ADSL and FTTC. Ask every supplier whether each device works on a digital line, needs an adaptor, or needs replacing.
What replaces your landline?
For most businesses, the replacement is a cloud (VoIP) phone system. Calls run over your internet connection, and you can use desk phones, mobile and desktop apps, or both. Modern systems add auto-attendant, call recording, voicemail to email, working from home on the business number, and Microsoft Teams integration.
Can you keep your phone number?
Usually, yes. Existing business numbers, including local 029 numbers, are moved across by porting. It takes some lead time, which is another reason not to leave it late.
What about power cuts?
Digital lines need mains power and will not work in a power cut without a battery or other backup. Divert calls to mobiles automatically and put the router on a small battery backup if the phones are critical.
Your switch-off checklist
- Review every number, line and device that uses a phone line; find current contracts and end dates.
- 2. Check that your business broadband (/broadband) or leased line (/leased-lines) can carry calls and decide whether you need a backup.
- 3. Test alarms, card machines and lifts with their suppliers.
- 4. Choose handsets, apps and call flows.
- 5. Port numbers, install the new system, train the team, then cancel old lines.
Switching in Cardiff and South Wales
Older buildings in Cardiff and Cardiff Bay often have mixed cabling and awkward Wi-Fi, which affect call quality. A provider who will visit, check data cabling (/data-cabling) and Wi-Fi (/wifi), and stay for support makes for a smoother switch than an online-only setup. See our guide on how to switch from landline to VoIP (/how-to-switch-from-landline-to-voip-a-practical-guide-for-businesses).
Frequently asked questions
When is the PSTN switch-off? Traditional phone lines need to move to a digital service by 31 January 2027.
Will the deadline be extended? Openreach has said the deadline is locked and there is no extension.
Does the switch-off affect broadband? Copper-line broadband including ADSL and FTTC is affected.
Can I keep my business phone number? Usually, yes. Your number can be ported to your new digital phone system.
Will my alarm or card machine still work? Not necessarily. Check every device that uses a phone line with its supplier.
Get a free line check
Crystal Voice Data is a Cardiff-based Gamma Accredited Partner and O2 Business Partner. We'll review your lines, numbers and connected equipment and plan a move to a business phone system (/office-phones) that keeps your 029 number. Book a free line check (/contact-us) or call 0333 5678 444, Monday to Friday, 9am to 5pm.
