PSTN Switch-Off: A Guide for UK Businesses

• What is the PSTN switch-off?
• Why is this happening?
• Who is affected?
• Will my business be moved over automatically?
• Common mistakes
• Why VoIP is an upgrade, not just a replacement
• How Zadarma helps you make the switch
• A simple migration plan
• How to migrate your phone number to Zadarma
• Conclusion
• FAQs

For over a century, the Public Switched Telephone Network (PSTN) has handled the UK's phone calls. Traditional phone lines have kept businesses connected to their customers.

This is now coming to an end. The switch-off started slowly in 2023, and at the end of January 2027 the network shuts off permanently. Any business still on analogue phone lines will need to move to a digital service before then. It might look like an inconvenience, but it's also a good chance to improve how you communicate, work more flexibly, cut manual tasks, and spend less.

This change isn't unique to the UK. Several countries have already shut down their copper networks, while others are in the middle of the same transition.

What is the PSTN switch-off?

The PSTN is the copper-wire network that has handled calls for generations. It runs traditional landlines and ISDN, the lines many companies use for their office systems. The network is now outdated. Maintaining it is expensive, and it no longer meets the demands of modern business communication.

BT Openreach is shutting it down and moving voice calls onto IP-based technology, or Voice over Internet Protocol (VoIP). Instead of dedicated phone lines, your calls travel over your internet connection. This affects businesses of every size that haven't moved yet.

One point worth clarifying: your phone number isn't affected. The switch-off removes the wiring behind it, not the number itself. You can keep the same number by moving it to VoIP, and doing so is easier than most people think.

Why is this happening?

This is not only about ageing infrastructure. It also reflects how businesses operate today. Most businesses today already use, or are looking for, features such as:

• Remote and hybrid working
• Access from a mobile
• CRM integrations
• Smarter call routing
• Call analytics and reporting
• Automation tools
• AI features

Traditional phone lines were never designed for these demands and often cannot meet them. Cloud-based systems provide these features, reduce costs, and simplify how your business stays connected.

Who is affected?

If your business still uses traditional phone lines, you'll probably need to move. That includes anyone using:

• Traditional desk phones
• PSTN and ISDN lines
• Older on-site phone systems (PBX)
• Lift emergency phones
• Security and alarm systems

Phone systems are among the easiest of these to modernise. If you already make calls over the internet, you're unaffected, since a VoIP or cloud phone system is precisely what replaces the PSTN. Mobile numbers are separate and aren't part of the switch-off.

Will my business be moved over automatically?

Generally, this is not the case. Home users on a basic landline are often migrated automatically by their provider. Business lines and systems are treated differently.

If you do nothing, your lines will simply stop working at the deadline. And even where an automatic migration is offered, it places you on your provider's terms, with no opportunity to compare features or pricing. Managing the move yourself lets you choose the provider, control the timing, and improve your setup in the process.

Common mistakes

Many businesses assume the task is simply swapping one phone line for another. It isn't. The switch-off is an opportunity to improve how your business communicates. A few things to watch for:

Leaving it late. As more businesses prepare, providers grow busier and number porting queues lengthen. Starting early gives you time to test the system, train staff, and move your numbers without pressure.

Rebuilding the old system exactly as it was. Your communication needs have probably changed since your phone system was installed. Consider what would serve you better now.

Overlooking remote work. Employees increasingly work from different locations. A well-chosen phone system lets them handle business calls from a laptop, mobile, or desktop app, wherever they are.

Why VoIP is an upgrade, not just a replacement

Moving to VoIP is about far more than maintaining a phone service. It gives you tools that improve the experience for your customers and your team. A modern cloud phone system can include:

• Smart call routing
• Interactive Voice Response (IVR) menus
• Call recording
• Voicemail-to-email
• Mobile and desktop softphones
• CRM integrations
• Call analytics and reporting
• International virtual phone numbers
• AI tools

Most of this comes as part of the service, so there's no additional hardware to buy.

How Zadarma helps you make the switch

Preparing for the switch-off does not have to be complicated. Zadarma is a cloud-based VoIP service that replaces traditional business phone systems without costly on-site equipment.

With Zadarma, you can:

• Keep your existing UK numbers through porting
• Set up a free Cloud PBX in minutes
• Build IVR menus and call queues
• Allow your employees to work remotely
• Use softphones on Windows, macOS, iOS, Android, or straight from a web browser
• Keep an on-site phone system connected through a SIP trunk, if you're not ready to replace it
• Connect your cloud PBX to popular CRM systems
• See detailed call reports and analytics
• Buy virtual numbers in over 110 countries and use them on a single platform
• Use a built-in Teamsale CRM and AI voice agent
• Access 24/7 multilingual customer and technical support

Whether you have two employees or several hundred, the platform is built to scale with you.

Important: Due to local regulations, UK numbers can only be used to call UK destinations from within the UK.

A simple migration plan

Getting ready is more straightforward than it may seem. Here are the steps to follow:

1. Audit your current setup. List every device and service that runs on traditional lines.
2. Identify what you actually need. Do you still require desk phones, or would mobile applications better suit your team?
3. Choose a provider. Look for reliability, room to scale, and the features you'll use every day.
4. Port your numbers. Your customers won't notice any change.
5. Test before going live. Avoid any disruption during the switch.

How to migrate your phone number to Zadarma

Before migrating, we recommend signing up and testing the cloud PBX. This allows you to configure the system, familiarise yourself with it, and resolve any questions with our support team in advance.

Please note that Zadarma does not provide remote setup services. Instead, we offer detailed setup guides and 24/7 multichannel support. The trial period allows you to prepare the system fully, so everything is in place once your number is migrated.

Number migration is free of charge. However, to port a number, you'll need to prepay for twelve months in advance, based on our number fees. For example, a London number has a monthly fee of £1.70, so the annual cost comes to £20.40, which you'll need to add to your account balance. Alternatively, you may activate a monthly or annual Office or Corporation price plan.

Once your account is ready, open a support ticket and attach your most recent invoice from your current provider. The invoice must show your first name, last name, address, and the number you wish to port. Our technical support team will then send you a form to complete. From there, they'll handle the rest of the process and keep you informed at each stage.

The migration of a UK landline number typically takes between 7 and 30 days.

Conclusion

The PSTN switch-off marks the end of traditional telephony, but it opens the door to something better. Rather than replacing one ageing system with another, you can use cloud communications to work more flexibly. Additionally, VoIP can support teams wherever they are, improve customer service, and reduce costs.

Plan your move early and choose a reliable VoIP service provider such as Zadarma. This will leave you well prepared not only for the switch-off, but for the future of business communications.

FAQs