Big Switch Off: what does the PSTN switch off mean for my small business?

Landlines will be fully-phased out in the UK in 2025, with some areas being switched off this year. Find out what the Big Switch Off means for SMEs and how to prepare.

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Helena Young

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The PSTN Big Switch Off is fast approaching. Openreach by BT is currently upgrading the outdated, analogue Public Switched Telephone Network (PSTN) to a faster, full-fibre digital network. This means the time is fast coming for businesses to commit to VoIP phone communications and clever tech such as virtual landlines to move their communications network into the future.

By the end of December 2025, any business or home phone call will instead be hosted over Internet Protocol (IP). Named the ‘Big Switch Off’, the move has big implications for any firm using broadband in its operations. In today’s world, that’s pretty much everyone.

To prepare for the change, all existing phone systems and older internet connections including any used by hardware like card machines and CCTV will need to transition to an IP mode.

The later you postpone the shift, the more complicated and costly the process will become especially if you don’t leave enough time to research the right provider.

In short, the Big Switch Off might not be happening until 2025, but the preparation starts now. This guide will outline what the change means for small businesses, what the risks and opportunities are, and how to get ready.

PSTN Switch Off dates

  • September 2023 – any broadband or phone services that use the old copper network will no longer be sold.
  • December 2025 – the PSTN will be switched off and all UK landlines will cease to operate.
  • From January 1 2026 – all home or phone calls will be hosted via the internet.

What is the Big Switch Off and why is it happening?

PSTN, which stands for Public Switched Telephone Network, is the traditional telephone network that first facilitated calls across the UK in 1875.

Exactly 150 years later, BT Openreach has decided the equipment is too old to stay in use. The company has already begun work on upgrading the old copper wires that currently make up the PSTN.

Over the next two years, Openreach will swap these wires out for fibre-optic cables as part of the so-called Big PSTN Switch Off. Simply put, it’s bye-bye landlines, and every home and business in the UK will instead be moved onto a digital network.

As a result, telephone lines that aren’t running over the internet through IP will no longer be supported by the UK networks from the year 2025, onwards. Other companies with their own networks, such as Virgin Media, plan to follow a similar timescale.

What is the Integrated Services Digital Network (ISDN)?

The ISDN was introduced to the PSTN in 1986 by BT to transmit data that the PSTN couldn’t facilitate previously, like video calls.

However, the ISDN is now outdated and only available in older teleconferencing systems and similar legacy systems.

Why is IP better than the ISDN?

Because fibre optic cables ensure a stronger internet connection, IP telephone systems are a high-quality method for calls than ISDN. This gives users:

  • Much faster broadband speeds
  • Lines that are less prone to damage, meaning fewer faults
  • Stable broadband speeds
  • Strong signal over greater distances

What does the Big Switch Off mean for my business?

Any business that currently uses ISDN in its operations will be affected by the PSTN Big Switch Off, which is why it’s important that every firm starts preparing for the change by upgrading their business telephone system.

The Big Switch Off will essentially shutdown all technologies currently running through the ISDN, such as:

  • Alarm systems
  • ATM machines
  • Franking machines
  • Fax machines
  • Printers
  • Dial-up POS (card machines)
  • Video conferencing 
  • Live streaming
  • File downloading

Once the PSTN has been turned off, businesses will lose all service if they are still using legacy products connected to ISDN.

Sara Sheikh is the head of product management at Gamma, a telecommunications provider. Sheikh predicts that the PSTN Switch Off “will have far-reaching implications for every industry”.

Brick-and-mortar businesses are not immune from the change. “Retail, hospitality, and other customer-facing businesses will need to update their systems to ensure that they can still provide quality customer service,” Sheikh clarifies.

How should I prepare for the Big Switch Off?

To prepare for the Big Switch Off, UK organisations should purchase or upgrade their existing broadband package to a VoIP (Voice over Internet Protocol) subscription.

For firms that have ISDN telephone lines at present, now is the time to shop around from the top business telephone providers to find the best small business VoIP system.

If you want to stick with your current provider, start a conversation with their customer service team now about the options available. Should you need to buy new equipment, like a new router, your provider should be able to arrange this.

Card machines and other hardware is a different story. If your machines still connect to a physical telephone line, we would recommend finding a unit that uses WiFi.

When should I update my system to prepare for the Big Switch Off?

Don’t feel confused if you’ve only just heard about the Big Switch Off. A recent Which? survey shows that 74% of consumers with a copper landline connection are unaware of the migration.

That said, Openreach has already begun the copper switch off in some locations, which means anyone who hasn’t already upgraded their service is now playing catch-up.

Kristian Torode is the director and cofounder of the business telecoms provider, Crystaline. He says SMEs must make the move early enough to ensure a seamless transition.

“There could be some interruptions to services as businesses scramble to upgrade,” Torode cautions. “There are over 25 million connections to be switched over by 2025. Making the switch sooner rather than later will be essential.”

The risks for businesses of not switching to a VoIP system in time include:

  • Choosing the wrong supplier: give yourself time to research the best business telephone providers and save money in the long-term
  • Increased costs: get a deal early supplier scaremongering could see VoIP prices getting pushed up closer to the deadline
  • Missing out on fast broadband: with some locations already offering fibre-optic internet, you could already be missing out on the benefits

What are the benefits of switching to VoIP?

Amongst the benefits of switching to a VoIP system, business users will get:

  • Better connectivity: faster broadband will improve your team’s productivity and overall output, having a positive impact on profitability
  • Improved customer relationships: having a faster, more stable telephone infrastructure means a better experience for product or service users
  • Flexible packages: because most VoIP packages work on a per-user pricing model, SMEs can save money by prioritising the connections they require
  • Cheaper deals: VoIP prices will become more competitive over time as Openreach incentivises suppliers to migrate more customers onto these future-proofed products
  • Supports remote working: Kristian Torode explains that by using VoIP number porting, “…any device can connect to the system on one phone number to support flexible working.”

Tom Grange is the head of connectivity at Bionic, a business broadband provider. Grange explains, “The service is quicker and more adaptable than copper and ISDN lines. Calls can be made from smartphones and laptops from wherever you are, with high-quality sound.”

PSTN Switch Off: do I need to switch my system?

Simply put, yes. There will not be an option for businesses to continue on the PSTN. From September 2023, if you can get Full Fibre, Openreach will not let suppliers order any new broadband or phone services that rely on the old copper network.

This means they will no longer sell any more legacy products using ISDN. Current equipment will continue to work for at least another two years, but this infrastructure will not support calls without a separate VoIP service. 

However, while the move might be inevitable, now is still a good time to audit your current telecommunications strategy. You might be able to save money by getting rid of any products that aren’t being used.

What should I look for in a VoIP phone system?

Duncan Shaw, the director at Connectus, a tech firm, recommends that SMEs don’t see the switch-off as a straightforward process of replacing what they have today. “Consider how you want to make communications work for you to maximise your ability to reach customers.”

1. Connectivity

Perhaps the most important aspect of a telephone provider is the strength of their connection. Be sure to carry out thorough research into every brand's broadband speed. That way, you can have confident in a reliable connection that will keep you closely connected with customers.

2. Flexibility

If you have a hybrid workforce, it makes sense to purchase business mobile phones rather than upgrade to a brand-new telephone system. “It’s vital to take informed decisions, remove risk, and minimise the complexity from the process,” says Shaw. “This, in turn, will help you to control costs.”

3. Number porting

Number porting is the process of moving a telephone number from one communications provider (CP) to another. It can take weeks, depending on the system you use, so it's a good idea to ask your provider how long the change will take to mitigate any business disruption.

Learn more: top five features every office phone system should have 📞

Big Switch Off: next steps

We've been helping small business users to find the right new phone system for their company for over two decades. We know that migrating existing business technology is stressful. But it’s important that SMEs recognise the huge opportunities that the Big Switch Off presents not just the challenges.

Transitioning to a VoIP subscription as soon as possible will give business owners access to a much cheaper and more powerful call infrastructure. IP systems give firms access to high-quality lines, which can boost productivity and help ensure a seamless customer experience.

To get ready for the change, small businesses should begin their research now. Start by comparing quotes with our simple cost comparison webform to find the best provider for your budget. It’s entirely free and will recommend the most suitable VoIP system for you based on your unique user needs and feature requirements.

Related reading:

The Big PSTN Switch Off FAQs
  • Apart from IP, are there other PSTN alternatives?
    No. All telecommunication will be conducted through the internet, which means businesses must move to an IP form to prepare for the Big Switch Off, like VoIP.
  • How do I know if my provider will switch me to another plan?
    Your provider will contact you to tell you when the service is moving and help you switch. If you want to move to a VoIP service now, you can do so by upgrading to a new phone and broadband package.
  • How much will the PSTN switch off cost me?
    In the long-term, you should save money as a result of switching. IP is typically cheaper to run than the old copper network as it uses the internet, not expensive infrastructure.
  • How would I make a call if there was a power cut?
    Providers are prepared for this. Once the Big Switch Off has occurred, back-up batteries will ensure that calls can be placed in the event of an emergency.
  • Is VoIP more reliable than PSTN?
    Yes. Once landlines have been phased out, VoIP will run with fibre optic and be more reliable than PSTN. Currently, PSTN uses old copper wiring to relay data, which is subject to damage and more likely to experience poor connectivity.
  • Can I keep my current landline number with the PSTN switch off?
    Yes. Unless you change broadband providers, you will be able to keep the same business phone number, so there shouldn’t be any disruptions to your operations.
  • When will landlines be phased out?
    In December 2025, all UK landlines will be phased out as part of the PSTN switch off. From 1 January 2026, all video and audio calls will instead by hosted over IP (Internet Protocol).
  • Do I need to buy a new phone after the PSTN switch off?
    No, your broadband provider should send you any new equipment needed to transition to VoIP. This includes all telephone handsets and a new router, if relevant. is reader-supported. If you make a purchase through the links on our site, we may earn a commission from the retailers of the products we have reviewed. This helps to provide free reviews for our readers. It has no additional cost to you, and never affects the editorial independence of our reviews.

Written by:
Helena Young
Helena is Lead Writer at Startups. As resident people and premises expert, she's an authority on topics such as business energy, office and coworking spaces, and project management software. With a background in PR and marketing, Helena also manages the Startups 100 Index and is passionate about giving early-stage startups a platform to boost their brands. From interviewing Wetherspoon's boss Tim Martin to spotting data-led working from home trends, her insight has been featured by major trade publications including the ICAEW, and news outlets like the BBC, ITV News, Daily Express, and HuffPost UK.

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