The PSTN switch-off explained: what UK businesses need to do

The Public Switched Telephone Network — PSTN — is the copper-wire system that has carried phone calls in the UK since the 1800s. Openreach is switching it off, and the deadline that matters is the end of January 2027. After that date no analogue or ISDN lines will work, anywhere in the UK.

Stop-sell already happened in 2023. That means you can't order a new analogue line at all, and most providers won't let you take over an existing one when you move offices. So even if 2027 feels a long way off, the practical deadline is sooner than you think.

What actually goes away

• Standard analogue phone lines ("PSTN").
• ISDN2 and ISDN30 — the digital business lines a lot of older phone systems sit on.
• Anything dialling out over those lines: alarm panels, lift emergency phones, door-entry systems, fax machines, EPOS card terminals using a phone line, and PDQ machines.

Broadband that runs over the old copper (ADSL and FTTC) is also affected, because the line it depends on goes away. Most businesses have already moved to fibre, but it's worth checking — we still see FTTC in older premises across rural Lincolnshire.

What replaces it

For phone calls, the replacement is VoIP — voice carried over your internet connection. In practice this means one of two things. Either you keep your handsets and plug them into a small adaptor, or you replace the phone system entirely with a hosted setup where each user logs in from a desk phone, a laptop or their mobile. Hosted VoIP is what most small businesses end up with, because it's more flexible and you can take calls from anywhere.

For alarms, lifts and card machines, you'll need a digital replacement — usually a 4G/5G fallback unit or a connection over your broadband. This is the bit businesses forget, and it's the bit that bites: a lift with a dead emergency phone is a legal problem, not just an inconvenience.

A sensible order to do this in

• Make a list of every device in the building that has a phone line plugged into it. Don't trust your memory — actually walk round.
• Check your broadband. If you're on FTTC or ADSL, you'll need to move to FTTP, SoGEA, or a 4G/5G connection.
• Plan the phone system move. Pick a hosted VoIP provider, port your numbers (you keep them), and roll out handsets or apps.
• Replace alarm and lift dialler units before your line gets switched.
• Keep proof. When you cancel the old lines, the provider will write to you — file that letter with your compliance paperwork.

If you'd like us to audit your lines and put a switch-off plan together, get in touch. We're doing a lot of these across Lincolnshire at the moment and the lead times are starting to stretch.