What is VoIP? A quick guide to modern business comms
The Big Switch Up: What’s changing with UK phone lines and when?
The Big Switch Up is the UK’s move away from old copper phone lines to modern, internet-based calling. It sounds technical, but at heart it is a simple change in how phone services are delivered.
With the 2027 switch off approaching, businesses are starting to ask what this means for them. This guide explains the basics, clears up common worries and shows how to prepare without the stress.
What is the Big Switch Up?
The Big Switch Up is the name given to the final push to move all UK phone services off the old copper network and onto digital, internet-based alternatives.
By January 2027, traditional phone lines will stop working altogether. Any service still relying on PSTN or ISDN will need to switch to an all-IP solution to keep calls, systems and services running as normal.
You might also hear this referred to as The BT Switch Off or the Big Switch Off. These are simply different names for the same change.
Why is the old phone network being switched off?
The traditional phone network was built decades ago, long before broadband, cloud services and flexible working became the norm. Known as PSTN and ISDN, it relies on ageing copper infrastructure that is expensive to maintain and increasingly unreliable.
At the same time, how we communicate has changed. Most calls now travel over the internet, not dedicated phone lines. Keeping two networks running no longer makes sense, especially when the older one cannot support modern business needs.
Switching to an all-IP network means clearer calls, better resilience and technology that is fit for the future. The switch off is less about taking something away and more about moving everything forward.
For more information on this, check out Openreach’s official guide on moving over from analogue to digital phone lines.
Key dates and what they mean
The switch off is not happening overnight, but the closer we get to 2027, the more pressure there is on businesses still using old phone lines. Costs rise, options reduce and timelines tighten.
| Date | What’s happening | What it means for businesses |
| Now | PSTN and ISDN still working | Time to review your phone lines and connected services |
| 2026 | Price rises and reduced support | Keeping legacy lines becomes more expensive |
| January 2027 | PSTN and ISDN switched off | Old phone lines stop working completely |
| After 2027 | Emergency voice only fallback for some | Limited, poorer service if no upgrade is in place |
The key message is simple. The earlier you act, the easier and smoother the change will be.
Who does the big switch up affect?
The short answer is almost everyone. If you have a phone line, there is a good chance the switch off affects you in some way. Here’s how it breaks down.
1. Small and medium-sized businesses
Most UK businesses still have at least one service running over PSTN. Often it is a legacy line that has been in place for years and quietly forgotten about. When the switch off happens, those lines will simply stop working unless they are upgraded.
2. Businesses with multiple sites or remote workers
Multi-site organisations and home workers often rely on older phone lines for call handling, backup or resilience. These setups can be more complex, which makes early planning especially important.
3. Anyone using “hidden” phone lines
Some of the most critical services are the easiest to miss. Alarms, payment terminals, lifts, door entry systems and intercoms often depend on PSTN behind the scenes. If these are overlooked, the impact can be serious.
4. Landline-only or low-usage businesses
Even if a phone line is rarely used, it is still affected by the switch off. A quiet line today can quickly become a problem if it is needed in an emergency and no longer works.
The safest approach is not to assume. Taking stock of every line now helps avoid disruption later.
What happens if you do nothing?
Doing nothing might feel like the easiest option, but it comes with real risks as the switch off gets closer. Even the UK government has confirmed that traditional landlines will be withdrawn as part of the national move to digital services.
- Your phone lines will stop working. After January 2027, PSTN and ISDN lines will no longer carry calls. No upgrade means no service.
- Costs will keep rising. Legacy lines are already becoming more expensive, with further price increases designed to push remaining users to move.
- Limited fallback services. Any emergency voice-only options are basic, cost more and offer a poorer experience than modern alternatives.
- Hidden services could fail without warning. Alarms, payment terminals or entry systems may stop working if they rely on old lines.
- Less choice and more pressure. Leaving it late reduces your options and increases the chance of rushed decisions or disruption.
How B4BC can help: At B4BC, we help businesses understand exactly what they have today and what needs to change. No jargon, no pressure. Just clear advice and a practical plan. If you are unsure where to start, get in touch and we will guide you through it.
What replacing PSTN actually looks like
For most businesses, replacing PSTN does not mean losing phone calls. It means changing how those calls are delivered. Instead of travelling over copper phone lines, calls are carried over your internet connection.
This is often referred to as VoIP or all-IP calling. In simple terms, your phone service becomes another digital tool, much like email or video calls. The way you answer calls may feel the same, but the technology behind it is more flexible and reliable.
Depending on your setup, this could mean using desk phones that plug into your broadband, a softphone on a laptop or mobile, or a cloud phone system that works wherever you are. For many businesses, it is an upgrade rather than a compromise.
The key is matching the right solution to how you actually work. When done properly, the switch improves call quality, supports modern working and removes reliance on ageing infrastructure.
Will the switch over be disruptive?
One of the most common concerns around The Big Switch Up is disruption. The good news is that, for most businesses, it does not have to be disruptive at all.
In many cases, calls can be moved to digital services with minimal downtime, sometimes just a short interruption while the change happens. There is not always a need for engineers on site, and existing numbers can usually be kept.
Problems tend to arise when the switch is rushed or when hidden services are missed. That is why understanding what each line is used for is so important. A well-planned migration feels controlled and predictable, not disruptive.
The earlier you prepare, the more choice you have. That makes the whole process smoother and far less stressful.
Why acting early makes life easier
The Big Switch Up is happening whether businesses are ready or not. The difference is how smooth the experience feels. Acting early gives you far more control over the outcome.
- More choice and better options. Early movers can choose the right solution for how they work, rather than being pushed into a last-minute replacement.
- Lower costs and fewer surprises. Legacy line prices are rising. Moving sooner helps avoid paying more for services that are being phased out.
- Time to uncover hidden lines. Early planning makes it easier to spot alarms, entry systems or payment services that rely on older connections.
- A calmer, planned transition. With time on your side, changes can be tested, scheduled and communicated properly.
The Big Switch Up doesn’t need to feel rushed. Starting early turns it into a planned upgrade rather than a reactive fix.
How to prepare for The Big Switch Up
You don’t need a technical background to get ready. A simple, step-by-step approach goes a long way.
| Step | What to do | Why it matters |
| 1. Audit your lines | List every phone line and connected service | Many businesses are surprised by how much still relies on PSTN |
| 2. Identify what each line supports | Phones, alarms, payment terminals, entry systems | Hidden services are the biggest risk if missed |
| 3. Check broadband readiness | Make sure your internet can support voice services | Digital calling depends on a stable connection |
| 4. Plan the right replacement | Match solutions to how your business works | Avoid overpaying or choosing the wrong setup |
| 5. Schedule the change | Move services in a controlled way | Reduces downtime and avoids last-minute pressure |
The key is starting early. Once you understand what you have, the path forward becomes much clearer.
Get ready for The Big Switch Up with B4BC
The Big Switch Up can feel daunting at first, especially when you are not sure which services rely on old phone lines. That is where the right support makes all the difference.
At B4BC, we help businesses make sense of what they have today and what needs to change before 2027. We take the time to understand how you work, identify any hidden risks and recommend practical, future-ready solutions.
No jargon. No pressure. Just clear advice and a smooth path through The Big Switch Up.
If you want to get ahead of the switch off and avoid last-minute stress, get in touch with the B4BC team today.
The Big Switch Up FAQs
The final deadline for The Big Switch Up is January 2027. From this point, PSTN and ISDN services will no longer operate. Any business still using traditional phone lines will need to have moved to a digital, IP-based alternative to keep services running.
Price rises on legacy services begin on 1 April 2026. Further increases follow on 1 July 2026 and 1 October 2026, creating a clear financial push to move away from PSTN ahead of the 2027 switch off.
Legacy service prices increase in stages during 2026. On 1 April prices rise by 20 percent over November 2025 levels, increase to 60 percent on 1 July, and reach 100 percent by 1 October 2026.
WLR withdrawal refers to the removal of Wholesale Line Rental services that support PSTN phone lines. This withdrawal will take place in January 2027 and marks the end of traditional copper-based voice services in the UK.
If you do not migrate before the deadline, your service may stop working or be moved to a basic emergency voice-only solution. These fallback options are more expensive, limited in functionality and not designed for normal business use.
