Migrating Your Business Telephony from PSTN to VoIP in 2023: A Guide for UK Businesses

Migrating Your Business Telephony from PSTN to VoIP in 2023: A Guide for UK Businesses

It’s no secret that technology is evolving at an astonishing rate, and this evolution often comes with both opportunities and challenges. One such change set to unfold in the year 2025 is the permanent shutdown of the Public Switched Telephone Network (PSTN) by BT. 

But “What exactly is PSTN, and why should I care?” you might ask. 

Put simply, PSTN is the backbone of traditional landline telecommunications. Think of it as the grandparent of modern communication technology. PSTN relies on analogue technology and a physical network of copper cables to transmit sound. Remember the days of picking up a telephone receiver and hearing that familiar dial tone before making a call? That’s the world of PSTN we’re talking about. 

The impending shutdown of PSTN means that you’ll need to make some significant changes in how your business communicates, and the clock is ticking. 

UK businesses that continue to rely on PSTN will lose the ability to make and receive calls, communicate via fax machines, and potentially even access the internet could be compromised. 

So, if your business is still using PSTN for your telecommunications, you will need to switch to another service as soon as possible or risk losing your business continuity. 

In the upcoming sections of this blog, we’ll delve deeper into what alternatives exist and the steps your business can take to smoothly transition away from PSTN.

In this article, we cover:

How do I know if I’m using PSTN?

Before we delve into the intricacies of transitioning to alternative services, it’s essential to recognise that PSTN (Public Switched Telephone Network) isn’t solely confined to traditional phone systems. Various technologies and services rely on PSTN infrastructure, including door entry systems, CCTV networks, fax machines, PSTN alarm systems, and even electronic point-of-sale (EPOS) systems. However, in this article we will be focusing on telephony and traditional phone systems. 

But first, how do you determine whether you are currently using PSTN for your business communication? 

Understanding your current setup is crucial because it will inform your transition plan as you prepare to migrate to a more modern solution and address the impending changes. 

Here are some pointers to help you identify if your business relies on PSTN: 

  1. Analogue Phones: If your office phones are the traditional analogue type, connected to phone jacks and using landline numbers, you are likely using PSTN. 
  2. Fax Machines: PSTN is commonly used for fax machines. If your business relies on faxing with a traditional fax machine, PSTN is involved. 
  3. ISDN Services: Integrated Services Digital Network (ISDN) lines are often associated with PSTN and may be used for voice and data transmission. 
  4. DSL Internet: If your business’s internet service is provided through DSL (Digital Subscriber Line), it often shares the same physical infrastructure as PSTN. 
  5. Dial-Up Modems: If you still use dial-up modems for internet connectivity, it’s a clear indication of PSTN usage. 
  6. Traditional Phone Bills: Review your phone bills. If they include charges for traditional phone lines, PSTN is likely in use. 
  7. Consult Your Provider: Reach out to your telecommunications service provider. They can provide specific details about the technology your business is currently using. 

I’m using PSTN, what do I do?

As the PSTN switch-off moves into a critical phase with the ‘stop sell’ regulation being enforced nationwide in the UK this month, the discontinuation of PSTN isn’t just about saying goodbye to an outdated technology; it is about ensuring the continued functionality and communication capabilities of your business.  

To prevent disruption, it is crucial you move to digital telecommunication as soon as possible. Our top recommendation at Sereno is to switch to Business VoIP without delay. 

VoIP (Voice over Internet Protocol) is a form of digital communication that enables you to make voice calls using broadband internet connection, rather than relying on traditional phone lines.  

This means you are no longer bound by the limitations of traditional phone lines, and it opens a world of possibilities for your business communications. 

Why business VoIP?

BT encompassed this perfectly when they said that “Internet calls, video conferencing, and online collaborative tools have far exceeded the capabilities of PSTN, and it is becoming increasingly difficult to maintain. By the end of 2025 PSTN will be switched off across the United Kingdom, ushering in a new era of telecoms.” 

With 2025 on the horizon, it makes sense for UK businesses to make the switch to business VoIP now, thus making the transition smoother and meaning they won’t fall short due to an influx of last-minute requests as the date for PSTN shutdown draws nearer. 

But, more importantly, VoIP provides a superior and more affordable alternative to traditional landlines. Not only do they offer enhanced capabilities, seamless scalability and better cost-efficiency, but they are also more equipped for the modern way of working, enabling easy hybrid working wherever your team is located. 

VoIP vs PSTN – how do they compare?

VoIP phone service is generally considered a more flexible, affordable and efficient means of telecommunication than PSTN. Meaning lots of UK businesses already favour using VoIP. 

The table below shows you exactly how they compare: 



Business VoIP 

Connectivity type 

Traditional physical telephone lines 

Internet connectivity 


Most providers offer monthly payment plans. Businesses must also pay for the installation and maintenance of physical infrastructure, namely wires, phones and lines. 

No installation or setup fees as connectivity relies on your existing broadband. Businesses typically pay a small monthly fee based on the number of employees using VoIP, starting from as little as £20 per month. 


To scale, businesses need to buy additional dedicated lines and hardware which can be expensive and time-consuming. 

Business owners using VoIP can easily add more users as and when their business grows, giving full flexibility. Typically, the more users, the more expensive the monthly fee.  

Business continuity 

Services generally remain active during power outages. Although cordless phones will not continue to work, and employees will need to bring landline phones with them if they suddenly need to work from home. 

VoIP will stop working only when internet connection is lost. It’s recommended that businesses factor this into their disaster recovery plans, having a back-up for lost internet connectivity.  

Call features 

PSTN providers sometimes give call forwarding, waiting and transferring as standard, although they can incur an extra cost. Video conferencing is not possible. 

Call forwarding, waiting, transferring and video conferencing are all included as standard. 

Tracking and reporting 

PSTN offers minimal reporting capabilities. 

Business VoIP has advanced reporting capabilities, calls can be recorded and tracked to then be used for employee training and KPI setting. 

Third-party integrations 

Unable to integrate with third-party tools. 

Can integrate with many popular third-party tools and apps, making for more efficient working and better tracking and reporting. 

How does business VoIP work?

We’ve established that a VoIP phone service is a cost-effective and adaptable form of telecommunication. But how does it actually work? 

Because VoIP uses the internet to connect, employees can make calls either directly from a computer, from a specialised VoIP phone or through a traditional phone that’s connected to a special adapter. Making calls through a computer means employees can log on and get started straight away without the need for an additional device, perfect for those that work between home and the office. VoIP calls can also be made on the move, by taking advantage of wireless hotspots and 4G/5G connection.  

If you decide to switch to business VoIP, you’ll first need to choose from VoIP providers UK and decide on a plan that suits the needs of your business, i.e., how many users you’ll have making calls (we can help with this!). You’ll then get the necessary hardware and software to get started (e.g., VoIP phones and servers). Your business VoIP service provider will set up your connection and maintain your VoIP system for you – then you’re ready to go! 

Ready to switch to business VoIP? Here’s what you need to know

So, you’ve heard why PSTN is shutting down and why VoIP is a more favourable option regardless. Now, you’re ready to switch. But before you do, here’s what you need to consider before, during and after the migration process.

1 – Preparing for the switch to business VoIP

Before switching to VoIP, you need to know that your internet line has enough bandwidth to handle the amount of calls you’re making. Most internet providers will be more than capable of this, as the minimum required bandwidth for a singular call is miniscule. However, it’s worth checking before you get started to prevent any potential disruption to your operations. 

It’s best practice to have VoIP using a secondary internet line for calls, rather than using your primary one. This means you’ll be backed up if one internet line goes down as you can simply switch to the other whilst it’s being fixed. Some telephony providers can even provide an ‘Assured IP line’ specifically for telecommunications. Typically, these are cheaper because they don’t require as much bandwidth, so you don’t need a leased line.  

Next, make sure that your existing handsets work with VoIP. Many traditional phone systems won’t be compatible with a modern business VoIP system. You’ll also need to consider whether you want to move to desktop or mobile apps for your phone systems. Currently, most businesses are taking advantage of remote working, so it makes sense that your VoIP system mirrors this, by ensuring that employees can access it easily from home, in the office or on the go. 

Lastly, consider any additions you may want that are available. Business VoIP can provide you with a number of useful features, including menu systems, voicemail, call recordings, call stats and reporting. Consider how you would use these and how they could benefit your business.  

2 – During the switch to business VoIP

Your VoIP service provider and/or IT partner will fully support you throughout your migration to VoIP. This will include thoroughly testing your new VoIP system by running systems alongside one another initially and testing on separate numbers before porting the main numbers over.  

To ensure the migration is seamless, we advise that you:  

  • Request demos of cloud-based VoIP systems for free and test them where you can so you have a good idea of the best solution for your business 
  • Clearly document your telecommunications process, or desired telecommunications process, including menu systems, hunt groups, call trip-overs and direct dials 


Note that switching to a new number can sometimes take a while so prepare for this and speak to your provider to get a clear timeline. 

3 – After the switch to business VoIP

  • Continue testing and ask staff to record any problems they have 
  • Re-document any changes to your system setup and call flow  

Switch to business VoIP with Sereno IT

Over 60% of UK businesses have already switched to VoIP, so what are you waiting for? Switching your telecommunications to a more flexible and affordable alternative couldn’t be easier.  

The easiest way to choose from VoIP providers UK is to do so with the support of your IT partner. At Sereno, we will help you scope out the right provider and plan for your business, acting as your point of contact so that all of your technical support is under one roof. Getting your support through Sereno means you’ll benefit from:  

  • The support service that you expect, with consistent and agreed SLAs in line with the rest of your IT support 
  • A dedicated team of IT experts who will liaise with your VoIP provider for you, so you don’t have to get stuck in the middle  
  • Business VoIP relies on your network infrastructure and connectivity, which we already manage, so you know you’re in safe hands 
  • We can help with the instalment process, ensuring your VoIP is set up in a reliable way that’s easy for us to support 
  • We can give you transparent advice about the best VoIP providers and plans for your business  
  • We can get you set up using VoIP with even more competitive pricing due to our long standing and trusted relationships with world-class suppliers  


For more information, contact us today and speak to one of our friendly team about how Sereno can help you switch to business VoIP.  


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