PSTN switch-off, explained properly.
The UK's copper phone network shuts down 31 January 2027. Stop Sell is already in force. Every business still on PSTN or ISDN — phones, alarm panels, lift emergency lines, PSTN-dependent card terminals — must migrate before then. Honest guide to what's happening, what it costs, and what to do.
- ☁️ Hosted VoIP (cloud PBX)
- 🔗 SIP trunks (keep existing PBX)
- 💼 Microsoft Teams Phone
- 📞 Number porting (01/02/03/0800)
- 🚨 Alarm panel migration (GSM)
- 🛗 Lift emergency line conversion
- 💳 EPOS terminal migration
- 📋 Pre-migration audit (free)
What's happening, when.
The UK's PSTN switch-off isn't a single event — it's a sequence already in motion. Here's where we are.
September 2023 — Stop Sell on copper. BT Openreach stopped selling new PSTN and ISDN lines across the UK. From this point, any new business connection had to be IP-based. Businesses with existing copper lines kept them, but no new ones could be ordered.
2024–2026 — Regional all-IP migrations. Openreach has been migrating specific telephone exchanges to all-IP one at a time, area by area. Businesses in affected exchanges receive 60-90 day notice before their local switch-off. Hundreds of UK exchanges have already migrated; thousands more by 2026.
31 January 2027 — National PSTN/ISDN switch-off. The final cutover. All remaining PSTN and ISDN circuits cease to function. No further extensions are planned. Businesses not migrated by this date lose voice connectivity entirely.
Why this matters now, not in 2027: Q4 2026 is going to be a capacity bottleneck. The UK telecom industry simply cannot migrate every remaining business in the final 90 days. Number porting timelines, engineer availability, handset supply chains — all will be constrained. The businesses that wait until December 2026 to start migrating will be the ones left scrambling. The businesses that migrate in 2026 have the calm choice.
Everything PSTN does today.
It's not just desk phones. Several common business systems run over the copper phone network — and most businesses haven't catalogued which ones.
Desk phones & main lines
The obvious one. Traditional business phone systems running over PSTN lines or ISDN30 trunks. These need migration to hosted VoIP, SIP trunks or Teams Phone.
Alarm panel monitoring
Burglar alarm and fire alarm systems dial out to monitoring centres over PSTN. After switch-off, this fails silently — the alarm panel can't reach the monitoring centre. GSM or IP-based monitoring replaces it.
Lift emergency phones
Statutory requirement under EN 81-28. Every lift must have an emergency phone that works during a power cut. Most existing lift phones use PSTN. GSM lift phone modules replace these — and the work needs Building Regs compliance.
PSTN-based EPOS terminals
Older card payment terminals that dial out over PSTN to authorise transactions. After switch-off these stop working. Migration is to IP-network card terminals — most acquirers handle the swap.
Fax machines
Still in use in healthcare, legal and government supply chains. Migration is to fax-to-email gateways (incoming faxes arrive as PDF attachments) or to virtual fax services over IP.
Healthcare alert systems
Telecare pendants, fall detection alerts, and assisted living dial-out systems used in care homes and supported housing. Most use PSTN. Specific digital telecare replacements exist and are being rolled out sector-wide.
ATMs (free-standing)
Free-standing cash machines (e.g. in pubs, retail) often use PSTN dial-up for transaction processing. Migration is to GPRS, 4G or IP networks — usually handled by the ATM operator but worth confirming.
Door entry & gate intercoms
Block-of-flats and gated commercial premises often use PSTN dial-out for door entry systems. Migration is to GSM or IP-based intercom systems.
Anything we haven't listed
If you have a system on site you're not sure about, get it audited. The "we forgot about that" discovery on 1 February 2027 is the failure mode that hurts businesses most. Our free pre-migration audit catalogues every PSTN-dependent system.
Three real options. Which is right depends on what you have.
Hosted VoIP (cloud PBX)
Best for: small-to-mid businesses (1-50 users) wanting modern features without on-premises PBX hardware. Phones become apps + IP handsets. Mobile apps, video meetings, AI Receptionist add-ons all available.
Typical cost: £15-25 per user per month plus optional handsets at £80-200.
Read more →SIP trunks (keep your PBX)
Best for: established businesses with capable on-premises PBX hardware that still has useful life left. The PBX stays in place. Only the line into it changes from ISDN to SIP.
Typical cost: £8-15 per channel per month. Lower total cost than VoIP if PBX is depreciated.
Read more →Microsoft Teams Phone
Best for: businesses already running on Microsoft 365 / Teams across the organisation. Voice integrates directly into Teams — calls, voicemail, meetings, all in one app.
Typical cost: £8-15 per user per month for the Teams Phone licence plus calling plan, deployed via Direct Routing or Operator Connect.
Read more →The honest answer about which is right: if you don't have an existing PBX (or it's been around for over 10 years and needs replacing anyway), hosted VoIP is usually right. If your existing PBX is recent and working well, SIP trunks let you keep that investment for another 3-5 years before fuller VoIP migration. If you're a Microsoft 365 shop with Teams already deployed, Teams Phone is the obvious answer because it lives inside an app your staff already use. Telexico's free pre-migration audit looks at what you have today and recommends the path that suits your operation — not the one with highest margin to us.
What PSTN migration actually costs in 2026.
Pricing ranges based on typical UK SME deployments. Specific quotes depend on user count, geographic spread, existing equipment, number porting volume, and whether non-voice PSTN systems (alarms, lifts, EPOS) are included in scope.
Small business (1-10 users)
Hosted VoIP route: typically £15-25 per user per month all-in. Handsets optional at £80-200 each, or use softphone apps free. Setup project: typically £200-500 covering porting, configuration and training.
Total first year: typically £2,000-4,500 depending on user count, handset choices and added services like AI Receptionist.
Mid business (10-50 users)
Hosted VoIP or SIP trunks. Hosted VoIP: £15-22 per user per month. SIP trunks (if keeping existing PBX): £8-15 per channel per month for typically 5-10 concurrent channels. Setup project: typically £500-1,500.
Total first year: typically £4,000-12,000 depending on architecture choice and bolt-on features.
Larger business (50-200 users)
Usually SIP trunks or enterprise VoIP. Per-user pricing falls with scale; typically £10-18 per user. Project costs include site surveys, multi-location coordination, complex porting, and integrating with existing CRM/Microsoft 365 estate. Typically £1,500-5,000 setup.
Total first year: custom — depends heavily on architecture and SLA tier.
Non-voice PSTN systems
Alarms: typically £150-400 per panel for GSM module replacement, plus monitoring contract change. Lift phones: £200-500 per lift for GSM module installation. EPOS terminals: usually handled by your card acquirer at no cost or low swap fee. Other PSTN devices: case-by-case.
These figures are reasonable 2026 UK averages. Telexico's free pre-migration audit turns the ranges above into a hard quote against your specific operation — line count, handset inventory, PBX age, non-voice PSTN devices, multi-site complexity. The audit is genuinely free and there's no obligation to migrate with us afterwards.
UK engineering team. Hundreds of migrations. Honest scope.
PSTN migration is the core Telexico workload since 2023. We've moved hundreds of UK businesses — pubs, dental practices, retail chains, manufacturing operations, professional services firms — off PSTN/ISDN onto hosted VoIP, SIP trunks and Microsoft Teams Phone.
What we do differently: free pre-migration audit that catalogues every PSTN-dependent device in your operation (not just phones), honest recommendation of the right path for YOUR operation rather than the highest-margin product for us, number porting coordinated so cutover is same-day with zero gap, UK-based engineers on the day of cutover (not offshore tier-1 scripts), and a single named contact end-to-end from quote to live.
We are a UK business connectivity and communications provider — engineering-led, plain contracts, no mid-contract price rises, and ready to migrate UK businesses across hosted VoIP, SIP trunks, leased lines and the surrounding infrastructure under one UK relationship.
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Not ready to switch yet? Send us your current contracts, bills, or photos of your existing equipment. We'll review what you have, what you're paying, and where you could simplify, consolidate or improve — without any pressure to buy anything from us.
We benchmark your existing broadband, phones, mobile and IT against current UK market pricing and what your business actually needs.
Real engineer review of your current connectivity, voice setup, WiFi, security and continuity — strengths, gaps, and where you're overpaying or underprotected.
We tell you honestly what's available at your postcode — FTTP, leased line, alt-net carriers — and which makes commercial sense for your operation.
For businesses still on ISDN or aging on-premises PBX — an honest cost-and-feature comparison before the 2027 BT switch-off forces a rushed decision.
No hard sell. No fixed package pressure. If we're not a better fit, we'll tell you straight — and recommend what is.
Frequently asked questions
When is the PSTN switch-off happening?
The full PSTN and ISDN switch-off in the UK is currently scheduled for 31 January 2027. As of 2026, BT Openreach has already stopped selling new PSTN/ISDN connections (Stop Sell), meaning any business still on copper phone lines must migrate before the 2027 deadline. Some regional 'all-IP' migrations are already happening — businesses in certain exchanges have been notified of earlier cutover dates.
What happens if my business doesn't migrate before the switch-off?
After 31 January 2027, your existing PSTN or ISDN lines will stop working entirely. Phones, fax machines, alarm panels, lift emergency lines, EPOS card payment terminals using PSTN modems, and any other equipment dependent on analogue copper telephony will cease to function. There is no grace period — when the switch is thrown, the service is gone. Migrating early is the only safe option.
What replaces PSTN and ISDN?
Three main options: (1) Hosted VoIP — your phone system moves to the cloud, calls run over your business internet. Most common for small-to-mid businesses. (2) SIP trunks — your existing on-premises PBX stays in place but the line into it changes from ISDN to SIP. Common for established mid-sized businesses with capable existing PBX hardware. (3) Microsoft Teams Phone — voice integrated into Microsoft 365. Common for businesses already on Teams. All three run over IP and are PSTN-switch-off ready.
How much does it cost to migrate from PSTN/ISDN?
Depends on what you're replacing. For a small business (1-10 lines) moving to hosted VoIP: typically £15-25 per user per month, with optional handset costs of £80-200 per handset. For a mid-sized business (20-50 lines) keeping its existing PBX and moving to SIP trunks: typically £8-15 per channel per month. For an enterprise migration of 50+ lines: typically project-based pricing with custom SLA. Migration project costs (engineer time, configuration, number porting) are usually £200-£2000 depending on complexity. Telexico offers free pre-migration audits to give you a hard quote rather than estimate.
Will I lose my existing phone numbers?
No — number porting is standard practice. Your existing geographic numbers (01, 02), non-geographic numbers (03, 0800, 0345 etc.) and direct dial-ins (DDIs) all port to the new VoIP, SIP or Teams platform. Porting takes 7-14 working days for most ranges. We coordinate the port so your phones go live on the new platform the same day they leave the old one — no gap, no missed calls.
Do my alarm system, lift line and EPOS terminal need attention?
Yes — these are commonly missed in migration planning and cause the worst post-switch failures. Alarm panels using PSTN dial-out monitoring need GSM or IP-based alternatives. Lift emergency phones need GSM units installed. EPOS terminals using PSTN dial-up for card authorisation need to migrate to IP-based payment networks or be replaced. Telexico's PSTN audit identifies every PSTN-dependent device in your operation — not just the desk phones — and migrates all of them together. The audit is free and prevents the catastrophic 'we forgot about the lift phone' discovery on switch-off day.
How long does the migration actually take?
A small business hosted VoIP migration is typically 7-14 working days from quote acceptance to live: number porting takes 7-14 days in parallel with handset configuration, training and cutover planning. SIP trunk migration is faster, typically 7 days, because the PBX hardware stays in place. Enterprise migrations with multiple sites typically take 30-90 days. Best advice: don't wait. Q4 2026 is going to be a migration capacity bottleneck across the entire UK telecom industry — book early.
Is Telexico ready to migrate businesses now?
Yes — PSTN-to-IP migration has been the core Telexico workload since the 2023 Stop Sell announcement. We've migrated hundreds of UK businesses across the West Midlands and nationwide. UK engineering team, in-house support, carrier-agnostic across hosted VoIP, SIP trunks and Microsoft Teams Phone. Free pre-migration audit, hard quote, plain contract, no mid-contract price rises.
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