If your business still has a traditional phone line, an ISDN system or an alarm that dials out over copper, the clock is now very short. BT Group will retire the Public Switched Telephone Network (PSTN) by 31 January 2027, and Openreach describes that deadline as "locked". In its July 2026 update, Openreach's Director of All-IP said plainly that "there is no extension to the deadline".
This guide explains what is changing, what tends to get missed, and the practical steps to move your calls to a modern internet-based (VoIP) system without disruption.
What is actually being switched off
The PSTN is the copper-based analogue network that has carried UK landline calls for decades. It is being replaced by "All-IP" services, where voice travels as data over a broadband or fibre connection.
According to Openreach, the change "impacts all services powered by copper lines, including ISDN, and ADSL and FTTC broadband". BT Business also says ISDN is being retired, alongside its Featureline and multiline services.
How the timeline got here
The date has moved before, which is why some businesses assumed it would move again.
- September 2023: Openreach set a UK-wide "stop sell" from 5 September 2023, restricting its legacy line product (WLR) for new supply where a digital alternative is available.
- December 2023: Government and communications providers signed the PSTN Charter, a voluntary agreement to protect vulnerable people, especially telecare users, during the move. It was last updated on 22 January 2026.
- May 2024: BT Group refined its programme, with all customers expected to have moved off the analogue PSTN by the end of January 2027, to better protect vulnerable customers.
- October 2025: Openreach launched its "Prove Telecare" service nationwide to help telecare and health-alarm users migrate safely, and says all technical barriers have now been resolved.
- July 2026: Openreach estimated that around 1.5 million lines were still on the old network, about 350,000 of them at business premises, and launched a campaign to push the remaining migrations.
Staying put is also getting more expensive. Openreach raised the wholesale price of legacy line rental in three steps during 2026 (April, July and October), which it says effectively doubles the 2025 rental cost.
What happens to lines that are not moved
Do not plan around a safety net. BT Business says some services, including ISDN, Featureline, multiline and certain broadband accesses, cannot be moved automatically and "will stop working from 31 January 2027" if they are not moved to an IP solution. Other lines may be moved automatically to a basic IP service, which is unlikely to match what a busy office needs.
Openreach has said that a small number of lines, some supporting vulnerable customers and critical national infrastructure, may still be on the PSTN after the deadline. These will be moved to an emergency voice-only service from 1 February 2027 with a "very limited and basic feature set". That is a stopgap for exceptional cases, not a business phone system.
The hidden lines: check more than your phones
The handsets on your desks are usually the easy part. The surprises tend to be the other devices plugged into a phone line. BT Business lists alarms, EPOS machines, door entry systems and fax machines as examples, and Openreach adds payment terminals and lift alarms.
Openreach recommends a simple three-step approach:
- Review every piece of equipment that could rely on the PSTN. If you are unsure, ask your provider.
- Test it. Openreach offers free testing at its test labs to confirm All-IP compatibility.
- Switch to a digital solution as soon as possible.
A practical tip: walk the building. Look for phone sockets with cables going to boxes on walls, in comms cupboards, in lifts and behind tills. Make a list of each line number and what it does before anything is changed.
Plan for power cuts and broadband outages
Digital voice depends on equipment at your premises, such as your router and, on fibre, the Openreach modem, having power. BT's guidance is that a battery back-up unit keeps service working for at least an hour in a power cut. For a business, think about which phones, alarms and lifts must keep working, and plan battery back-up, mobile apps or a secondary connection accordingly.
Choosing your VoIP replacement
Moving to VoIP is a chance to get features a copper line never offered: calls on mobiles and laptops, call recording, queues, and integration with your other software. NETON is a Wildix Gold Partner and supplies Wildix, x-bees, Sangoma and Microsoft Teams Direct Routing, together with UK numbers and SIP trunks. Here is how the main options fit.
Wildix: a cloud phone system built for business
Wildix is a unified communications platform. With its cloud option, each customer gets their own PBX instance, described by Wildix as "isolated, secure and fully configurable". Users can call from the browser using WebRTC, from desk phones, or from the iOS and Android app. Importantly for the switch-off, Wildix says it offers "full support for existing analog equipment through our media gateways", which can help with devices you cannot replace straight away.
x-bees: for sales and customer-facing teams
x-bees is Wildix's customer communication platform. Wildix describes it as offering chat, voice and video calls with your teams, prospects and customers, native Salesforce integration, and AI tools including transcriptions and summaries. If your phones are mainly used to win and serve customers, it is worth a look.
Microsoft Teams with Direct Routing
If your staff already live in Microsoft Teams, you can make it the phone system. Direct Routing connects Teams Phone to a phone carrier of your choice through a Microsoft-certified session border controller (SBC). Microsoft notes it suits organisations that have an existing carrier relationship or need to connect third-party phone systems or analogue devices. NETON supplies certified SBCs from anynode, AudioCodes and Ribbon; see our SBC page for more.
You do not have to pick only one. Wildix offers a free plugin, teams4Wildix, which lets Teams users make and receive calls through a Wildix PBX without additional Microsoft licences, using a Wildix tab inside Teams.
Keep your numbers
Your existing numbers are part of your business identity, and moving to VoIP does not have to mean losing them. Porting UK numbers to a new platform is a routine process: Microsoft, for example, supports porting UK geographic and non-geographic numbers into Teams, and quotes 12 to 30 business days. Give yourself time, because the details on the request must match your current provider's records exactly. See our telecommunications services for UK numbers and SIP trunks.
A simple plan for the next few weeks
- List every line, its number and what it is used for.
- Ask your current provider which of your services are affected and what they plan to do with them.
- Test alarms, card machines and other devices, or ask their suppliers about digital-ready versions.
- Choose your new platform and order any SBCs, handsets or gateways.
- Start number porting early, then switch over site by site.
Frequently asked questions
When exactly is the UK PSTN switch-off?
BT Group will retire the PSTN by 31 January 2027, and Openreach said in July 2026 that there is no extension to the deadline.
Will my ISDN system keep working after January 2027?
No. BT Business says ISDN, Featureline and multiline services cannot be moved automatically and will stop working from 31 January 2027 unless they are moved to an IP-based solution.
Can I keep my existing business phone numbers?
Usually, yes. UK numbers can be ported to a new VoIP provider, but start early: porting relies on your request matching your current provider's records exactly, and Microsoft, for example, quotes 12 to 30 business days for UK ports into Teams.
What about alarms, lifts and card machines on phone lines?
They may stop working or need upgrading. Check each device with its supplier, and use Openreach's free equipment testing if you are unsure whether it is All-IP compatible.
Sources
- Time for a big switch up as PSTN switch-off looms — Openreach — 2026
- Openreach warns businesses: just six months left before the UK's old phone network is switched off — Openreach — 2026
- Openreach announces price changes to encourage digital adoption — Openreach — 2025
- All-IP programme: stop sell updates — Openreach — 2023
- Public Switched Telephone Network (PSTN) Charter — GOV.UK (DSIT) — 2026
- BT Group refines its digital switchover programme — BT Group — 2024
- The PSTN and ISDN switch-off: what it means for you — BT Business — 2026
- Set up battery back-up — BT — 2026
- Cloud VoIP PBX — Wildix — 2026
- x-bees UCaaS platform — Wildix — 2026
- teams4Wildix — Wildix — 2026
- Plan Direct Routing — Microsoft Learn — 2026
- Phone number management for the United Kingdom — Microsoft Learn — 2026
Talk to NETON
With only a few months left, the businesses that move now get to choose their timing. Those that wait risk having it chosen for them. If you would like help reviewing your lines, testing equipment or moving to Wildix, x-bees or Microsoft Teams, call NETON on +44 20 4602 3181 or use our contact form.
Phone: +44 (0)20 4602 3181 | Email: info@netontechnologies.com
Get a Free Consultation