What is actually being switched off?
The Public Switched Telephone Network (PSTN) is the copper-based analogue system that has carried UK phone calls for over 40 years. Openreach is retiring it - along with ISDN2 and ISDN30 - by 31 January 2027. Every service that rides on it needs to move to an IP-based alternative before then.
Why the deadline matters right now
Even though January 2027 sounds far off, a national "stop sell" is already in force - no new analogue or ISDN lines can be provisioned. Number ports, engineer availability and hardware lead times all get tighter the closer we get to the cut-off. Businesses that plan in 2026 pay less and have more choice than those that leave it to Q4.
The three paths for UK businesses
- Cloud Communications (SelectVoice) - a fully hosted phone system with AI features baked in. Best for businesses that want to retire on-premise hardware entirely.
- SIP Trunking - keep your existing PBX and swap the ISDN lines for a SIP connection. Best when your PBX is modern and you want to protect the investment.
- Microsoft Teams Direct Routing - turn Teams into your phone system with proper UK numbers and calling plans.
What to do this quarter
- Audit every line, including alarms, lifts, franking machines and payment terminals.
- Take our two-minute Readiness Check to see which path fits.
- Lock in a migration window early - engineer diaries fill up fast in the run-up to 2027.
The switch-off is not optional. But it is a chance to modernise: lower call costs, better mobile working and AI features that were impossible on copper.
