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The UK PSTN switch-off: what 31 January 2027 means for your phone lines

The analogue landline network that UK phones, faxes and alarm panels have relied on for decades is being switched off. Here's what changes, what's at risk, and the painless way to move.

By the DIDcomms team · Updated November 2026 · Verified against Ofcom, gov.uk and Openreach sources

The UK's traditional phone network — the Public Switched Telephone Network (PSTN), along with ISDN business lines — is being retired. Openreach's current programme ends with the network fully closed on 31 January 2027. After that, analogue phone lines stop working, and every service that secretly depends on them needs a new home.

Sources: BT Business PSTN switch-off guide; Focus Group PSTN guide; Yay.com ISDN switch-off guide. BT/Openreach originally targeted the end of 2025 and extended the programme to January 2027.

Quick timeline

WhenWhat happens
Sept 2023Openreach stopped selling new WLR (traditional phone) and ISDN lines — no new analogue lines for new or existing customers.
2024–2026Exchanges migrate area by area as full-fibre (FTTP) and All-IP services roll out; customers are moved proactively.
31 January 2027The PSTN and ISDN are fully withdrawn. Analogue lines and ISDN channels stop working.

What actually stops working

It's much more than home phones. Any device that dials or listens on an analogue line is affected:

If you run alarm systems: panels using PSTN dial-up signalling (including TAP-style messaging) must move to an IP-based route before switch-off. See our TAP to SMS guide — and DIDcomms' OpenTAP already supports TAP over TCP/IP as a no-phone-line option.

What "All-IP" means for your business

Voice is moving to the same IP networks as your broadband. In practice businesses choose one of two routes:

  1. Keep a line-shaped service: an ATA adapter or a router with an FXS port turns your broadband into a phone socket. Minimal change, minimal flexibility.
  2. Go virtual (recommended): a UK virtual number from a provider like DIDcomms routes calls to mobiles, landlines or SIP apps. You keep your existing number by porting it, add features like voicemail-to-email, auto attendant and business-hours routing, and you're never tied to a physical socket again.

Can I keep my existing number?

Yes. Number porting is a regulated process — your number moves to the new provider when you switch. DIDcomms supports porting UK numbers, so the number your customers already know keeps working across the switch-off. If you'd rather start fresh, you can activate a new number instantly and run both in parallel during the cutover.

The 90-day panic-proof checklist

  1. Find your copper: list every line, alarm, lift phone, fax and door entry system on your site(s).
  2. Ask "what dials out?": anything that does needs an IP path before January 2027.
  3. Sort your voice: decide between an ATA adapter or a virtual number with forwarding.
  4. Move early: engineers get booked solid in the final months — don't compete with the rush.
  5. Test after the move: inbound, outbound, voicemail and alarm signals.

FAQs

When exactly is the UK PSTN switch-off?
Openreach's programme ends on 31 January 2027, when the PSTN and ISDN are fully withdrawn. Exchange migrations run throughout 2024–2026, so some areas are switched off before the final date.
Will my landline number stop working?
The number doesn't die — the analogue line does. Port your number to an IP-based or virtual service and it keeps working; DIDcomms supports UK number porting.
What happens to my intruder alarm or fire panel?
Panels that signal over a phone line must move to IP-based signalling before switch-off. TAP-style alerting continues over TCP/IP with gateways such as DIDcomms OpenTAP.
Is ISDN the same as PSTN?
No — ISDN is the digital business line service that runs over the PSTN core. Both are being withdrawn together in the same programme.
Do I need full fibre to keep a phone?
You need an IP connection — full fibre (FTTP), SoGEA or another broadband service. Voice then runs over that connection as VoIP, or through an adapter if you want to keep existing handsets.

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