A VoIP phone system makes and receives business calls over the internet instead of through traditional phone lines. Your voice is converted into data, sent through your broadband connection and turned back into sound at the other end.
For most UK businesses, the real question is no longer whether it exists but whether it’s time to move. The UK’s legacy copper phone network is due to be retired on 31 January 2027, and Openreach has said there will be no further delay. If your phones depend on analogue or ISDN lines, you will need a digital alternative.
This guide explains how the technology works and helps you decide whether it fits your business.
How a VoIP Phone System Works
A traditional phone system, or PBX, is a box in your office wired to physical lines. A VoIP system replaces the lines with your internet connection. The “brain” that routes calls can sit on your premises, or it can be run by a provider in their data centres, which is known as a hosted or cloud PBX.
Your team still gets a handset or an app, and customers still dial a normal UK number. The difference is that settings like call routing, voicemail and extensions are managed through a web portal.
The Main Types
Hosted: the provider runs the system, and you pay per user each month. Most small businesses choose this route.
On-premise IP PBX: you own the system and connect it to the outside world with SIP trunks. This suits firms that want to keep existing equipment.
Hybrid: a mix, often used by multi-site organisations migrating gradually.
Most guides to Voip phone systems in the UK focus on the hosted model, because it removes on-site hardware and is the simplest to manage.
What You Get Day to Day
The features that make the biggest practical difference are often the simplest.
Auto attendant: a menu such as “press 1 for sales” that routes callers
Ring groups: several phones ring together or in sequence
Voicemail to email: messages arrive as audio files or transcripts
Mobile and desktop apps: staff use the business number from anywhere
Call logs and reports: you can see missed calls and busy periods
Anything beyond that, such as call recording or CRM integration, is worth adding only if your team will use it.
Signs You Probably Need One
There is no universal answer, but a few situations make a strong case.
You still rely on ISDN or analogue lines. These will stop working when the PSTN is retired, so replacement is not optional.
Your team works across locations. If staff split time between home, the office and client sites, a hosted setup lets calls follow the person, not the desk.
Your phone changes are slow or costly. If adding a starter or changing opening hours means waiting for an engineer, a web portal is a clear upgrade.
You miss calls and don’t know why. Reporting tools can show patterns, such as most missed calls arriving between 8:30 and 9:30 each morning.
You’re planning to grow or move. Adding seats is simpler than buying more hardware, and numbers can move with you.
When You Might Not Need to Rush
It’s worth being honest about this side too.
If you have a recent IP PBX that works well, you may only need SIP trunking to replace the lines, not a whole new system. If your site has poor or unreliable broadband, such as some rural locations, sort out the connection first. And if your phone use is very light, a simple business mobile plan may genuinely be enough.
The one thing you can’t ignore is the deadline for legacy lines. Even if you keep your equipment, the lines themselves need to change.
Choosing the Right Setup for Your Size
Small Teams
A small business phone system with VoIP should do the basics well: clear call routing, a dependable app and voicemail to email. A hosted phone system for a small business keeps costs predictable, since you pay per user and add seats as needed.
Larger Organisations
A hosted phone system for a large business has different priorities: multi-site routing, user permissions, reporting, CRM integration and clear service levels. Many larger firms also add unified communications such as chat and video.
Choosing Handsets
People often ask which is the best VoIP phone. It depends on how your team works. Receptionists and sales staff generally benefit from quality desk phones with good headset support. Hybrid staff may prefer a softphone app. Cordless IP handsets suit larger offices where people move around. Ask providers which brands they support and whether you can bring your own.
What to Check Before You Switch
Your Internet Connection
Call quality depends on your network, not just the provider. Fibre broadband is a sensible baseline for most offices. Many business routers can prioritise voice traffic over downloads, and wired desk phones are usually more reliable than Wi-Fi.
Backup Plans
An analogue line could keep working during a power cut. Digital voice needs power and connectivity. Plan for this with a router battery backup and automatic call diversion to mobile numbers.
Your Phone Lines and Devices
A VoIP phone line replaces your old lines, but many businesses forget what else uses them. Alarms, lift emergency lines, CCTV links, door entry systems and card payment terminals may all depend on phone lines. Ask each supplier what their digital replacement will be.
Costs
Pricing typically combines a monthly fee per user, call bundles or per-minute rates, and handset costs. Calls to mobiles, international numbers and 03 or 08 numbers can be priced differently, so ask for a worked quote based on your real call habits.
Security and Data
Ask where call data is stored, how recordings are protected and how the provider handles GDPR.
A Simple Example
Consider a 12-person estate agency with an ageing ISDN line. Negotiators spend half their time at viewings, and calls to the office often go unanswered.
They move to a hosted system. Calls to the main number ring reception, then roll to negotiators’ mobile apps, then voicemail. Missed-call reports show peaks on Monday mornings, so they adjust rota. Nobody visits the cupboard where the old PBX used to live.
Next Steps
List your lines, numbers and devices, including alarms and card machines.
Test your broadband and check router settings.
Decide which features you’ll use, rather than paying for a long list.
Request quotes from two or three providers and compare pricing structure, support and contract terms.
Plan your cutover well before January 2027, keeping the old service live until the move is confirmed.
Providers such as Wavetel Business work with UK organisations on this kind of move, and any provider you consider should be willing to put their plan and pricing in writing.
Frequently Asked Questions
What is a VoIP phone system in simple terms?
It’s a business phone service that sends calls over the internet. A hosted version is run by a provider, and you manage it online.
Is VoIP the same as a cloud phone system?
They overlap heavily. VoIP describes the technology, while “cloud phone system” usually means a hosted service, often with extras like video and chat.
Do I need special phones?
Not always. Softphone apps work on laptops and mobiles, but many older analogue handsets are not compatible. IP desk phones generally give better call quality in the office.
Can I keep my existing number?
In most cases, yes, through number porting. Timescales vary, so start early.
What happens if my internet goes down?
Calls are affected unless you have a failover plan. Providers can divert calls to mobiles, and a backup connection adds further protection.
Conclusion
A VoIP phone system is a practical way to run business calls over the internet, with more flexibility and easier management than fixed lines. Whether you need one depends on your lines, your team and your plans, but with the PSTN closing, anyone on legacy lines has to act.
The takeaway is to start with an audit of your lines and devices, test your broadband and ask providers detailed questions before you commit. Starting early leaves time to move calmly.
