The Phone Line Switch-Off: What Your Business Needs to Check Before 31 January 2027

On 31 January 2027, the UK’s old copper telephone network is being switched off for good. After an earlier delay, the deadline is now fixed. Every phone line has to move to a digital service that runs over the internet.

Most businesses think of this as “something to do with the office phones”. It’s much more than that. Plenty of equipment quietly relies on an old phone line, and nobody notices until it stops working.

According to Openreach, around 1.5 million lines were still on the old network in summer 2026, and roughly 350,000 of those belong to businesses. With about three months to go, now is the time to check yours.

What is actually changing?

For decades, phone calls have travelled over copper wires through the Public Switched Telephone Network, known as the PSTN. That network is being retired and replaced with digital lines that carry calls over a broadband connection.

You may already have heard terms like “Digital Voice”, “VoIP” or “SIP”. Don’t worry about the names. They all mean the same thing in practice: your calls, and anything else that used your phone line, will run over the internet instead.

If you already use a modern cloud phone system or Microsoft Teams calling, your phones are probably fine. The risk is everything else.

What could stop working

Walk around your premises and look for anything plugged into a phone socket or that “dials out”. Common examples include:

• Intruder and fire alarms that call a monitoring centre when they’re triggered
• Lift emergency phones, which are a legal safety requirement in many buildings
• Card payment machines, especially older countertop terminals that connect through a phone line
• Door entry and gate systems that ring a phone when someone presses the buzzer
• Franking machines that top up credit over the phone line
• Fax machines, still surprisingly common in some sectors
• CCTV and building management systems that send alerts or allow remote access over a phone line
• Telecare and pendant alarms, important in care homes and supported living

Some of these will keep working over a digital line. Others won’t, or will work unreliably. The only way to know is to check each one with the supplier who installed it.

The power cut problem

Here’s the part that catches people out. An old copper phone line carries its own power, so phones keep working during a power cut. A digital line relies on your broadband router, which needs mains electricity.

If the power goes off, so does your phone service, and potentially your alarm’s connection to the monitoring centre. For most offices, a small battery backup (a UPS) for the router and phone equipment solves this. For alarms, lifts and anything safety-related, it’s essential to talk to the installer about backup options.

Your switch-off checklist

1. List every phone line you pay for. Check your phone bills. You may be paying for lines nobody remembers, such as an old fax or alarm line.
2. Find out what each line is used for. Match every number to a device or service.
3. Speak to your alarm, lift, door entry and payment providers. Ask them directly: “Will this work after the switch-off, and if not, what do we need?”
4. Check your broadband. Your phones will depend on it, so it needs to be reliable. Consider a backup connection that switches over automatically if the main line fails.
5. Plan for power cuts. Add battery backup for your router and phone equipment, and ask about backup for safety systems.
6. Don’t leave it until January. Engineers and suppliers will be busy as the deadline approaches.

Use it as a chance to improve your phones

The switch-off is also a good moment to review how your business takes calls. Modern cloud phone systems let your team answer the office number from a mobile or laptop, wherever they are. They usually cost less than old line rental, and they’re easier to change as your business grows.

But be careful about long contracts. We regularly see businesses tied into expensive phone hardware rental agreements where they end up paying far more than the equipment is worth. When we reviewed the phone system for Macey Industrial Fixing in Hailsham, we replaced their rented handsets with hardware bought outright at a fraction of the long-term cost. You can read more in our Macey Industrial Fixing case study.

If you’re weighing up your options, our guide to VoIP versus traditional landlines explains the practical differences.

What this means for your business

The switch-off isn’t optional and the date won’t move again. Most businesses will find the move straightforward, but only if they check everything that uses a phone line beforehand. The businesses that get caught out are the ones whose alarm or card machine stops working on 1 February.

Need a hand?

We help businesses across Sussex get ready for the switch-off. That means checking every line and device, talking to your alarm and equipment suppliers, setting up a reliable internet connection with backup, and moving your phones to a system that suits the way you work.

If you’re not sure what in your building still relies on an old phone line, get in touch or book a free call and we’ll help you find out.