What is the PSTN Switch Off and what does it mean for my small business?

Openreach by BT will officially switch over the outdated, analogue Public Switched Telephone Network (PSTN) to a faster, full-fibre digital network by 1 January 2026. As a result, your traditional landline connection will be replaced with Voice over Internet Protocol (VoIP) services.

By the end of December 2025, any business or home phone call will instead be hosted over 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.

2024 is the ideal time to prepare for the change.The later you postpone the shift, the more complicated and costly the process will become. 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

• Since September 2023, any broadband or phone services that use the old copper network are no longer 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 made via a VoIP-based system

What is the PSTN Switch Off?

The Public Switched Telephone Network (PSTN) is the traditional telephone network that was first established in 1875. 150 years later, BT Openreach has decided the equipment is too old to stay in use. The company has already begun to upgrade 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. As a result, every home and business in the UK will be moved onto a digital network from 2026.

The process is already underway. In September 2023, telephone providers including Virgin Media officially stopped selling hardware models that use the copper network. You will now need to purchase a modern communication system hosted via VoIP.

What is the ISDN Switch Off?

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However, the ISDN is now outdated and only available in older teleconferencing systems and similar legacy systems. Like the PSTN, the ISDN will be shut down in December 2025 in favor of modern technologies like VoIP.

Why are landlines being switched to VoIP?

VoIP telephone systems are hosted over the internet. Specifically, they use fibre optic instead of the PSTN’s copper cables. These ensure a stronger internet connection, meaning VoIP telephone systems are better for hosting higher-quality calls compared to both the PSTN and ISDN. This gives users:

• 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: how will I be affected?

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

Telecoms providers will take care of much of the migration admin, by contacting customers at least four weeks ahead of any switching over taking place in their region.

However, if you’re looking for a better broadband deal, savvy business owners are advised to use this time to purchase or upgrade to a small business VoIP system that’s better value-for-money.

How will I be affected?

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

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

VoIP can only be used to host phone or video calls. Card machines and other hardware cannot be hosted using VoIP software. If your machines still connect to a physical telephone line, we recommend finding a unit that uses WiFi.

I’m based offline – will I be affected?

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.

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” including brick-and-mortar businesses.

“Retail, hospitality, and other customer-facing businesses will need to update their systems to ensure that they can still provide quality customer service,” she clarifies.

PSTN Switch Off: when do I need to switch?

Although the official switch off won’t happen until the end of next year, switching to a modern, VoIP-based telephone provider should be done as soon as possible. That’s because not switching soon enough brings risks to businesses.

Kristian Torode is the director and cofounder of the business telecoms provider, Crystaline. “There could be some interruptions to services as businesses scramble to upgrade,” he 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

How do I switch to VoIP?

In our expert guide on how to prepare for the PSTN Switch Off, we outline the five steps to install VoIP. To start, companies should design a detailed migration plan as soon as possible to ensure they are considering budget, required features, infrastructure needs, and employee training.

The next step is to partner with the right provider. Research the top VoIP providers to ensure you are fully aware of each company’s strengths and weaknesses. Seek recommendations from fellow business owners and read reviews to make an informed decision.

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 automatically arrange this.

>> Read our guide to installing a VoIP telephone system to prepare for the Big Switch Off.

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: this 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.

PSTN Switch Off: next steps

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.

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:

• How to set VoIP up for home working
• How to install a VoIP phone system
• How much does a VoIP system cost?