The PSTN switch-off: a practical checklist for businesses
The UK’s traditional copper phone network, the PSTN, is being permanently retired on 31 January 2027. Openreach has confirmed there will be no further extension. ISDN, the digital lines many older phone systems use, is being withdrawn at the same time.
Most homes and businesses have already moved over. But in July 2026 Openreach reported that around 1.5 million lines were still on the old network, roughly 350,000 of them at business premises. Unlike home lines, business lines don’t have special protection from disconnection, so anything still connected to an old line could simply stop working.
The good news is that the move is usually straightforward, and it’s a chance to tidy up your phone and broadband costs. Here’s a practical checklist.
1. Find every line you pay for
Start with your bills. List every phone number and line, who supplies it and what it’s for. It’s common to find lines nobody remembers: an old fax number, a line for a burglar alarm, or a spare line left over from a previous office layout.
If a line isn’t needed any more, cancel it. Line rental on the old network is also rising, so unused lines are costing more each year.
2. Check what’s plugged into them
Phones are the obvious part. The things that catch businesses out are the devices that quietly use a phone line in the background:
- Intruder and fire alarms that call a monitoring centre
- Lift emergency phones
- Card payment terminals that dial out rather than using broadband or mobile data
- Door entry systems
- Franking machines
- Fax machines
- Telecare or lone worker devices
For each one, ask the supplier whether it works over a digital line or needs an upgrade, such as a broadband or 4G connection. Alarm and lift suppliers in particular will have a standard upgrade route.
3. Choose how your calls will work
Your phone calls will move to internet-based calling, usually called VoIP. There are two main routes:
- Like-for-like digital lines, which keep your existing handsets working through an adapter or new router. Simple, but you get little more than you had before.
- A cloud phone system, where your numbers move to a hosted system with desk phones, softphone apps and mobile apps. Calls can follow people between the office, home and mobile, with features like call queues, voicemail to email and call recording.
For most businesses with more than a few staff, a cloud phone system is the better long-term choice. You can keep your existing numbers, and it often costs less than the lines and maintenance it replaces.
4. Make sure your broadband is up to it
With calls running over the internet, your broadband becomes more important. Check that:
- Your connection has enough capacity for calls alongside everything else. Full fibre or a leased line is ideal.
- Your router and network can prioritise voice traffic, so calls stay clear when someone’s uploading large files.
- You have a backup plan, such as a 4G failover router or calls diverting to mobiles if the line goes down.
5. Plan the switch, don’t wait for it
Moving on your own timetable means you choose the date, test everything and keep your numbers without any gap in service. Leaving it until a line is withdrawn means doing it in a hurry. A sensible order is:
- Audit lines and devices.
- Upgrade alarms, lifts and payment terminals with their suppliers.
- Get broadband and networking in shape.
- Port your numbers to the new phone system and test.
- Cancel the old lines once everything is confirmed working.
How we can help
We help businesses across London and Hertfordshire move from old phone lines to modern business VoIP, and make sure the network and broadband underneath it is reliable. We’ll audit your lines, keep your numbers and handle the move so nothing gets missed.
If you’re not sure what’s still on the old network, get in touch or call 0203 8833 444 and we’ll help you find out.
See how we help serviced offices and restaurants and venues with phones and connectivity.
