Guide
Cloud Phone Systems
and UCaaS, Explained
A cloud phone system runs business calls over the internet instead of an office PBX. How it works, what UCaaS adds, UK costs, and what to check before buying.
By the AymexConnect team, Aymex LTDUpdated Published
In short
A cloud phone system (also called hosted VoIP or a hosted PBX) delivers business telephony as an online service: your numbers, call routing, voicemail and extensions live in the provider's data centre, and staff make calls through apps on computers and mobiles or through internet-connected desk phones. UCaaS (Unified Communications as a Service) is the same idea extended to video meetings, team chat and SMS in one product. You pay per user per month, there is no PBX to buy or maintain, and the system works wherever there is internet.
How it works
When someone dials your business number, the call arrives at your provider's platform over the public telephone network. The platform applies your rules (opening hours, a menu, a ring group) and sends the call over the internet to whichever of your devices should ring: a laptop app, a mobile app, or a SIP desk phone. Outbound calls go the other way. The audio is carried as data packets, usually encrypted, and sounds at least as good as a landline on a normal office connection.
Because the intelligence lives in the cloud, changes are made in a web dashboard rather than by an engineer. Adding a user, changing the opening-hours greeting or forwarding the main number to a mobile takes a minute.
Cloud phone system vs on-premise PBX
| Cloud phone system | On-premise PBX | |
|---|---|---|
| Upfront cost | None beyond any desk phones you choose to buy | PBX hardware, licences, installation, ISDN or SIP trunk |
| Ongoing cost | Per user per month, calling often included | Maintenance contract, line rental, call charges, upgrades |
| Remote and hybrid work | Built in: the same number on laptop and mobile anywhere | Needs VPNs or add-on softphone licences |
| Changes | Self-service in a dashboard | Engineer visit or support ticket |
| Resilience | Provider runs redundant data centres; you need a good internet connection | Depends on one box and one line in one building |
| PSTN switch-off | Unaffected | ISDN-connected PBXs stop working after 31 January 2027 |
What UCaaS adds
- Video meetings with screen sharing, from the same app and user account as calls.
- Team chat with channels, direct messages and file sharing, replacing a separate chat tool.
- Business SMS from your business number, so customers can text the same number they call.
- Shared contacts, presence (who is on a call) and call history across every device.
- Increasingly, AI: voicemail transcripts, call summaries, meeting recaps and writing help.
What it costs in the UK
UK cloud phone systems are priced per user per month, typically from around £8 to £15 for a plan with inclusive minutes and £15 to £30 for unlimited UK calling with video and chat, plus VAT. Enterprise suites run higher and are often quote-only. Watch for annual-only pricing, per-user minimums, desk-phone rental contracts, and AI or recording sold as add-ons. AymexConnect, for reference, is £8.95 for Starter and £17.95 for Professional with unlimited UK calling, video, chat, SMS and AI included.
What to check before you buy
- Contract: is the headline price monthly or only on a 12-month or annual term?
- Calling: inclusive minutes or genuinely unlimited UK landline and mobile calls, and what the fair-use policy says.
- Everything in one app: are video, chat and SMS included, or separate products and bills?
- Devices: apps for the platforms your team uses, and whether you can bring your own SIP desk phones.
- Numbers: free porting in, a UK number on day one, and emergency-services (999) address registration.
- Data and regulation: where call recordings and messages are stored, GDPR terms, and whether the provider meets Ofcom's General Conditions.
- Trial: can you test the full product with real calls before you commit?
Questions people ask
VoIP (Voice over IP) is the technology of carrying calls over the internet. A cloud phone system is a complete business service built on VoIP: numbers, routing, voicemail, apps and admin. UCaaS adds meetings, chat and messaging to the same service.
A voice call uses roughly 100 kbps in each direction, so most business broadband handles dozens of simultaneous calls. Quality depends more on stability and latency than raw speed; a wired connection or good Wi-Fi and a router that prioritises voice traffic make the biggest difference.
Usually, if they are standard SIP handsets (Yealink, Poly, Grandstream, Fanvil and similar). Proprietary handsets tied to an old PBX generally cannot be reused.
Yes. UK providers are required to connect emergency calls and to register an address for each user so the call handler knows where you are. Keep that address up to date when people move.
Sources
Third-party facts on this page were read from the sources below on the date shown. Providers change prices and terms; check their site before you decide.
- Ofcom General Conditions of Entitlement · checked 3 November 2026
- Expert Market: VoIP phone system pricing UK (2026) · checked 3 November 2026
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