The UK’s traditional telephone network (PSTN) switches off permanently on 31 January 2027. Every business still using analogue phone lines, ISDN, or copper-based services must migrate to a digital alternative before that date. As of February 2026, around 500,000 UK business lines haven’t switched yet — and Openreach has started aggressive price increases to force the remaining holdouts off copper.
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This guide covers exactly what the PSTN switch-off means for your business, the timeline, what you need to do, and how to choose a replacement phone system. If you’re still on traditional lines, you’re running out of time. From April 2026, copper line prices rise 20%, then another 40% in July, and another 40% in October — making delay increasingly expensive.
- PSTN ends 31 January 2027 - All traditional copper phone lines and ISDN connections permanently discontinued across the UK
- Affects 2.6 million businesses - Substantial number of UK companies still relying on legacy analogue telephone systems
- VoIP migration saves 40-60% - Modern internet-based phone systems typically reduce monthly telecommunications costs significantly
- 18-month preparation window - Limited time remaining for businesses to plan, procure, and implement replacement communication systems
- Card machines need upgrading - 500,000+ terminals using PSTN connections require replacement or connectivity updates before deadline
What Is the PSTN?
The PSTN (Public Switched Telephone Network) is the UK’s traditional phone network. It connects calls through copper wires and BT Openreach exchanges. The system has been in place since the 1800s.
When you make a traditional landline call, your voice becomes an electrical signal. It travels along copper wires to your local BT exchange. The exchange creates a dedicated circuit between you and the person you are calling. That circuit stays reserved for the entire call – even during silence.
The UK’s PSTN comprises approximately 5,600 local exchanges serving every home and business in the country. These exchanges use digital circuit-switching technology (primarily System X and Ericsson AXE-10 platforms) installed in the 1980s and 1990s.
Connected to the PSTN are two types of business phone lines:
- Analogue lines – single copper pair per line, one call at a time. Standard for small businesses and home offices
- ISDN (Integrated Services Digital Network) – digital lines providing 2 channels (ISDN2) or 30 channels (ISDN30). Used by businesses needing multiple simultaneous calls
Both analogue and ISDN lines are part of the PSTN and both are being retired in the switch-off.
Why Is the PSTN Being Switched Off?
The PSTN exchange hardware is 30-40 years old, increasingly expensive to maintain, and fundamentally less efficient than modern IP-based networks. Openreach is replacing it with an all-digital, all-IP network.
The decision to retire the PSTN is driven by three factors:
- Ageing infrastructure – the System X and AXE-10 exchanges date from the 1980s-90s. Spare parts are scarce. Engineers who understand the hardware are retiring
- Inefficiency – circuit-switching reserves a connection for every call, even during silence. IP packet-switching shares bandwidth dynamically. It handles far more traffic on the same kit
- Feature limitations – PSTN carries only voice and basic data. IP networks add video, messaging, presence, AI transcription, CRM integration, and remote working. None of these work on circuit-switched lines
What Is the PSTN Switch-Off?
The PSTN switch-off is the permanent retirement of the UK’s copper telephone network on 31 January 2027. All voice calls will move to internet-based (VoIP) technology, and analogue phone lines will stop working.
PSTN stands for Public Switched Telephone Network — the copper wire system that has carried UK phone calls since the 1800s. BT’s Openreach division, which maintains the physical network, has confirmed this infrastructure will be decommissioned by 31 January 2027. This date is final and will not be extended again (a previous December 2025 deadline was pushed back).
The switch-off affects analogue phone lines (POTS), ISDN services (ISDN2 and ISDN30), and any equipment that relies on copper phone lines — including alarm systems, PDQ card machines, door entry systems, lift emergency phones, and telecare devices.
Key Dates and Timeline
Stop-sell is already live at 1,281 exchanges. Price increases begin April 2026 (20%), escalating in July (40%) and October (40%). Full switch-off: 31 January 2027.
| Date | Event | Impact |
|---|---|---|
| Already live | Stop-sell at 1,281 exchanges | No new analogue/ISDN orders in these areas |
| 16 Feb 2026 | Temporary stop-sell relaxation begins | Helps difficult migrations at FTTP Priority Exchanges until Oct 2026 |
| April 2026 | Copper line prices rise 20% | Holding onto old lines gets more expensive |
| July 2026 | Copper line prices rise another 40% | Significant cost escalation |
| October 2026 | Copper line prices rise another 40% | Final push to force migration |
| 30 Oct 2026 | Stop-sell relaxation ends | No more exceptions |
| 12 Feb 2027 | Tranche 23 stop-sell activates | 132 exchanges, 1.23 million premises |
| 31 Jan 2027 | PSTN fully switched off | All remaining analogue/ISDN lines cease |
The price escalation strategy is Openreach’s clearest signal that delay is no longer cost-neutral. A business line costing £30/month today could cost £50+/month by October 2026 — while a VoIP replacement might cost £10-20/user/month with better features.
What Does This Mean for Your Business?
If your business uses analogue phone lines, ISDN, or any copper-dependent equipment, you must migrate to a VoIP or digital alternative before January 2027 or lose your phone service entirely.
Systems That Will Stop Working
| System | What Happens | Digital Replacement |
|---|---|---|
| Analogue phone lines (POTS) | Lines cease — no dial tone | VoIP phone system (cloud or on-premise) |
| ISDN2 / ISDN30 | Service terminated | SIP trunking or hosted VoIP |
| Fax machines | Won’t work on PSTN | Online fax services or email |
| PDQ card machines (dial-up) | No connection | 4G/broadband card terminals |
| Burglar/fire alarms | Can’t dial out to monitoring | IP-connected or 4G alarm systems |
| Door entry systems | No connection | IP intercom systems |
| Lift emergency phones | Won’t connect to emergency services | 4G lift phones |
| Telecare/pendant alarms | Won’t connect to monitoring centre | Digital telecare (Openreach “Prove Telecare” programme) |
Vulnerable Customer and Telecare Update
The telecare migration barrier — previously the biggest obstacle to the switch-off — has been resolved. Openreach launched “Prove Telecare,” a nationwide migration service with 4,000+ specially trained engineers. Battery backup units (minimum 1-hour standby) are being provided to maintain emergency connectivity during power outages. This was a critical requirement before the government would allow the switch-off date to be locked in.
How to Prepare: Step by Step
Audit your current phone lines, check your broadband speed, choose a VoIP provider, port your numbers, test the new system, and decommission old lines — ideally completing migration by Q3 2026 to avoid price hikes.
Step 1: Audit your current setup. List every analogue line, ISDN connection, and copper-dependent device in your business. Include alarm systems, card machines, fax lines, and door entry systems — not just phones.
Step 2: Check your broadband. VoIP requires a stable internet connection. Each concurrent call needs roughly 100 Kbps of bandwidth. If you have 10 staff making calls simultaneously, you need at least 1 Mbps of dedicated upload bandwidth. For most businesses, a standard fibre broadband connection (FTTC or FTTP) is sufficient.
Step 3: Choose a replacement phone system. For most SMEs, a cloud-hosted VoIP system is the simplest option. See our best business phone systems comparison. For larger businesses with on-premise PBX equipment, SIP trunking allows you to keep your existing hardware while moving to IP-based connections.
Step 4: Port your phone numbers. You can keep your existing business numbers (01, 02, 03 prefixes) when switching to VoIP. Your new provider handles the porting process — it typically takes 5-10 working days. There should be minimal downtime during the switch.
Step 5: Test before going live. Run the new system alongside your existing lines for a trial period. Test call quality, check all devices work correctly, and verify that alarm systems and card machines function on the new connection.
Step 6: Decommission old lines. Once you’re satisfied the new system works, cancel your analogue/ISDN lines with your current provider. Do this before the price increases hit in April 2026 to save money.
PSTN vs VoIP: How They Compare
VoIP (Voice over Internet Protocol) replaces the PSTN by carrying voice calls as data packets over your broadband connection, with cloud providers handling all the routing and infrastructure.
| Factor | PSTN (Traditional) | VoIP (Replacement) |
|---|---|---|
| How calls travel | Electrical signals over copper wires | Data packets over broadband |
| Infrastructure | BT exchange hardware | Provider’s cloud data centres |
| Line rental | £15-£20/month per line | No line rental – included in subscription |
| Call cost | Per-minute charges on most plans | Unlimited UK calls included |
| Simultaneous calls | 1 per analogue line, 2-30 per ISDN | Unlimited (bandwidth dependent) |
| Features included | Basic: call waiting, caller ID | Full: auto-attendant, voicemail, recording, video, mobile app, AI |
| Remote working | Not supported (desk phone only) | Built-in – use from any device, anywhere |
| Reliability | Works during power cuts (analogue) | Requires broadband + power (mobile backup available) |
| Status | Being retired 31 January 2027 | Standard for all new installations |
The one genuine advantage PSTN had was power-cut resilience – analogue phones drew power from the phone line itself. VoIP requires broadband and electricity. However, mobile phones provide a backup for emergencies, and many VoIP providers offer automatic mobile failover.
How Much Does Migration Cost?
Most businesses save money by migrating. A 10-person office paying £300-£500/month for ISDN lines and PBX maintenance can switch to cloud VoIP for £70-£250/month with more features.
| Business Size | Current PSTN Cost (typical) | Cloud VoIP Cost | Monthly Saving |
|---|---|---|---|
| 1-5 users | £80-£150/month (lines + calls) | £35-£125/month | £25-£50 |
| 10 users | £200-£500/month (ISDN + PBX maintenance) | £70-£250/month | £50-£250 |
| 25 users | £500-£1,000/month (ISDN30 + maintenance) | £175-£625/month | £100-£375 |
The savings come from three things. You drop line rental (£15-£20/line/month). Per-minute call charges go to zero on UK calls. PBX maintenance contracts disappear. Cloud VoIP includes unlimited UK calls, auto-attendant, voicemail, call recording, and a mobile app – all in the monthly subscription. With Openreach’s 20% (April), 40% (July), and 40% (October) price hikes through 2026, the case for early migration only strengthens.
Choosing a VoIP Replacement
UK businesses replacing PSTN lines should consider cloud VoIP providers like RingCentral, Dialpad, bOnline, or Vonage — all starting from £10-13/user/month with features that far exceed traditional phone lines.
| Provider | Price From | Best For | Key Feature |
|---|---|---|---|
| RingCentral | £12.99/user | Growing businesses | 300+ integrations, monthly contracts |
| Dialpad | £12/user | AI-first teams | AI transcription on all plans |
| bOnline | £9.95/user | Simple setup | UK-focused, easy onboarding |
| Vonage | £10/user | Supervisor tools | Whisper, barge, and monitor modes |
| BT Business | £9.99/user | BT loyalists | Familiar brand, UK support |
| Lily Comms | Quote only | Hands-on installation | Engineers visit your premises |
Most providers handle number porting, hardware setup (if you want desk phones), and configuration as part of onboarding. The transition from PSTN to VoIP is straightforward for the vast majority of businesses — but start the process now rather than waiting for the price increases to bite.
Read our full business phone system comparison or use our VoIP providers guide to find the right fit. If your business has ISDN30 lines or a PBX system, our SIP trunking guide explains the alternative route.
