The complete guide to business phone systems.
Everything a UK business needs to know about modern phone systems — how they work, what they cost, and how to choose the right one.
What is a business phone system?
A business phone system is the platform that handles all of your organisation’s calls — routing them to the right people, holding callers in queues, offering menu options, recording conversations and connecting your team whether they’re at a desk, at home or on the move. Modern systems do far more than the old switchboard: they tie together calls, voicemail, mobile apps and reporting into one managed service.
For most UK businesses today, that means a cloud-based system. Instead of a physical box in a comms room, the “brain” of the phone system lives in secure data centres, and calls travel over your internet connection. This is what people mean by hosted VoIP or a cloud PBX, and it’s rapidly replacing the traditional on-premise systems that depended on ISDN and analogue lines.
Why traditional systems are being retired
The UK’s old public switched telephone network (PSTN) and ISDN lines are being switched off by the end of January 2027. After that, the analogue and ISDN lines that many older phone systems rely on will stop working. Every business still using them will need to move to an internet-based system before then.
This isn’t just a compliance deadline — it’s an opportunity. Moving to a cloud phone system almost always lowers monthly costs, adds flexibility and unlocks features that simply weren’t possible on the old network.
Types of business phone system
Hosted VoIP / Cloud PBX: the modern standard — fully hosted, no on-site hardware, calls over the internet, pay per user. Ideal for the vast majority of businesses.
On-premise PBX: a physical system you own and maintain on-site. Increasingly rare due to cost, maintenance and the switch-off.
Microsoft Teams Phone: calling added directly into Teams via Direct Routing — excellent if your team already lives in Teams all day.
SIP trunks: a way to keep an existing capable PBX but replace the old ISDN lines feeding it with internet-based connections.
Key features to look for
Call routing and hunt groups so calls always reach someone; IVR auto-attendant menus (“press 1 for sales”); voicemail-to-email; mobile and desktop apps so staff can work anywhere; call recording for quality and compliance; and reporting so you can see call volumes, missed calls and team performance.
For busier operations, look for queues with announcements, wallboards, CRM integration and call analytics. A good provider will configure these around how you actually work, not hand you a generic template.
How much does a business phone system cost?
Cloud phone systems are typically priced per user per month, often from around £5 per user, with no large upfront cost. You pay for the number of people who need an extension, and you can scale up or down as your team changes.
Compared with a traditional system — hardware, installation, line rental and maintenance — cloud usually works out significantly cheaper over its life, while adding features and flexibility the old kit never had.
How to choose the right system
Start with how your team works: office-based, hybrid, fully remote or multi-site. Then think about call volumes, whether you need queues and menus, and any compliance requirements such as call recording. Finally, consider whether you want a classic handset-based system or calling built into Teams.
The most important choice is the provider. A local, independent provider that sets the system up properly and supports it directly will save you far more than a fractionally cheaper price from a faceless national reseller.
Migrating without disruption
A good migration keeps your existing numbers (we port them across), runs the new system alongside the old where needed, and cuts over with minimal downtime — often measured in minutes. New numbers can be live within the hour; porting an existing number takes a little longer and is scheduled carefully.
The key is planning: a provider who audits your current setup, times the move and supports you through it makes switching genuinely painless.
Frequently asked questions
What’s the best business phone system for a small business?
For most small businesses, a hosted VoIP / cloud system is best — low cost per user, no hardware, and full features. We size it to your team.
Do I have to switch before 2027?
Yes — the PSTN and ISDN network switches off by January 2027, so any system relying on those lines must move to internet-based calling before then.
Can I keep my phone number?
Almost always — we port your existing numbers across so customers notice no change.
How long does installation take?
New cloud setups can be live within the hour; porting existing numbers takes a little longer and is scheduled to avoid disruption.
Explore more
I can recommend connectivity, phones and AI in 30 seconds.