The PSTN Switch-Off 2027: What UK Businesses Need to Do Before 31 January 2027
If your business still relies on a traditional phone line, an ISDN system, or broadband running over copper, the countdown has started. Openreach has confirmed the UK’s Public Switched Telephone Network (PSTN) will be permanently switched off on 31 January 2027 — and the date will not move again.
This isn’t a niche telecoms issue. Alarms, lifts, door entry systems, payment terminals and older broadband connections often quietly depend on the same copper wiring as your phone line. As of May 2026, roughly 2.4 million UK lines still needed to migrate, around half a million serving business premises.
Here’s what’s changing, why waiting is getting more expensive, and how to migrate without disruption.
1. The Switch-Off at a Glance
Before covering each threat individually, it is worth understanding the overall picture. The table below summarises the six most significant cyber threats facing UK SMEs in 2026 — their prevalence, how they typically get in, and what they tend to cost:
| Milestone | Date | What It Means |
|---|---|---|
| National "stop sell" | 5 Sept 2023 | No new analogue or ISDN lines can be ordered |
| Wholesale price rises | Apr–Oct 2026 | Copper line rental rising in stages — up to double by year end |
| Full PSTN & ISDN switch-off | 31 Jan 2027 | All analogue and ISDN2/30 lines permanently disconnected |
| ADSL & FTTC broadband | Withdrawn with the line | Broadband sharing that copper line stops working too |