As the Public Switched Telephone Network (PSTN) Switch Off looms closer, is your business still weighing up the alternatives? If so, you need to act soon and find yourself a VoIP provider. From December 2025, anything your company has linked to the PSTN will stop working. And that deadline is going to come around fast.

Among other considerations, the PSTN Switch Off means you’ll need to migrate your landline to a digital phone system for small and medium-sized enterprises (SMEs). For that, you’ll need to take a closer look at Voice over Internet Protocol (VoIP), a communications technology that doesn’t use traditional copper phone lines.

Choosing a VoIP provider

To make the most of the opportunity, you’ll need to select the right supplier for your VoIP phone system. There are a lot of UK VoIP providers to choose from, but they don’t all provide identical solutions or the same levels of service. What seems like the right route for one company could be restrictive, or even too excessive, for another.

That’s why we’ve put together this guide. Read on, and make sure you ask all the right questions of your potential VoIP provider.

What is VoIP and how does VoIP work?

VoIP allows you to make and receive phone calls using your broadband connection. Unlike traditional phone systems, VoIP also allows you to call from your laptop, tablet or mobile phone, as well as a VoIP-compatible desk phone.

As you make all your calls over the internet, VoIP is extremely cost-effective. You also gain access to advanced phone features like a virtual receptionist, call waiting, call routing, customisable caller tones, multiple phone numbers, and much more.

VoIP works by converting your analogue voice into a digital signal, which then travels over the internet to its final destination. Unlike traditional phone lines, VoIP only sends data when needed, creating small, instant connections every time you speak. This all happens at high speed and you won’t notice any delay during the call. You’re also likely to experience higher sound quality when compared with an analogue phone line.

Now that you know some of the background to VoIP, let’s take a look at those questions that you need to be asking your potential VoIP provider.

How many calls can I make at a time?

VoIP allows your business to make and receive multiple calls over an internet connection at the same time, without needing to buy additional phone lines. The number of concurrent calls depends on the available bandwidth and your service provider’s policy.

Your potential VoIP provider should be able to assess your requirements and help you evaluate how many lines you’ll need. They should ask you questions about how much usage you anticipate, whether your sales or support staff have large call volumes, and if you’re running a call centre.

In addition, make sure you check their policies, processes and costs associated with adding or removing users. Some providers only allow businesses to increase lines, so ensure whoever you choose allows you to adapt to any business changes.

Do I need an existing VoIP phone and what other equipment will I need?

You have a wide range of hardware options when you choose a VoIP service. And because VoIP is based on open standards, you can use hardware manufactured by many different suppliers.

In fact, you can even get away with not buying any dedicated phone hardware at all. Instead, your business could use apps running on mobile phones and laptops. It all depends on your particular business model, whether you employ a hybrid working policy, and how you want your employees to operate.

Whatever equipment route you choose, be wary of a provider that insists on selling you lots of hardware or tying you to a specific brand without evaluating your business needs first. Some providers may also want to sell you phones that aren’t compatible with other platforms, which will make it difficult for you to switch later.

What features do you offer and what should I consider?

All VoIP systems can make and receive voice calls, put conversations on hold, transfer calls and mimic the functions of phone hardware. Additional features that could be available to you include video conferencing, conference calls, auto dialling, automatic service failover, call analytics and editable call flows.

You may also want instant messaging (IM), custom reporting, data export or call encryption. In addition, your sales and support staff may need to integrate with your customer relationship management (CRM) and helpdesk apps. If that’s the case, look for a provider that offers prebuilt integrations for the software you already use.

We won’t go into all the detail here, but make sure you know the extent of what’s on offer and what you’ll need, and if you can vary functionality by user rather than across the board. Taking another perspective, don’t add more features than your business requires, otherwise you’ll be needlessly paying for redundant functionality.

How will you help me through the setup phase?

During your conversations with your potential VoIP providers, ask them what support they offer during setup and onboarding. You may likely need some help establishing new technologies, deploying hardware and installing apps.

Is their help limited to written guidance? Is video-based or live one-on-one training provided? You may have a knowledgeable in-house tech team that can handle every aspect of the installation, or you may need steering through the process one step at a time. Whatever your requirements, make sure your potential supplier has everything covered.

Will my employees need training and what do you provide?

If a potential VoIP provider tells you that your employees won’t need any training, that’s a red flag. It’s likely what the provider really means is that they don’t offer training.

Although VoIP can be far more user-friendly and intuitive than an analogue phone system, getting familiar with it may take some time and training. Particularly if you choose additional features that many of your employees might not be familiar with.

Make sure your potential provider offers training in a format that suits you and your employees.

Are there any hidden costs when switching to VoIP?

Make sure you know exactly what your VoIP package is going to cost your business. Ask about all the up-front costs and recurring subscription costs. Sometimes, a quote will include only basic features, excluding the capabilities that most businesses require to function successfully. Check whether there are any further additional charges and whether your plan includes unlimited calls.

Additional costs could relate to bolt-on packages, international calls or termination fees. Try to avoid being locked into a long-term contract as well, as this can limit your future flexibility. It’s important that you have the full financial picture and can compare like with like.

What level of ongoing support can I expect?

If things go wrong or you need a helping hand, you need to know that you can count on your chosen provider. Ask whether you’ll have a dedicated account manager, and what the average response times are for support tickets.

Also, check whether support is outsourced to another country in a different time zone and what the hours of support are. Can you reach them through a range of communication channels quickly and easily? Perhaps test the response times yourself before you sign up.

Make your next move now

Now you know the key questions to ask your potential VoIP provider, it’s time to make the switch. December 2025 is not that far away, so you need to act fast.

Start your journey towards a PSTN-free future

If you’re not getting the support you want from your existing provider, then look at getting concise, consolidated support on telephony, connectivity and cloud upgrades from a specialist.

1–10 employees?

XLN is standing by

For VoIP solutions best suited to businesses with fewer than 10 employees, XLN are more than happy to help.

11–250 employees?

Daisy has got you covered

Speak to a Daisy Communications expert who can tailor the best solutions for you from providers like BT Wholesale, ITS, Gamma, 8×8 and more…