Complete guide to VoIP phone systems in the UK.
Everything UK businesses need to understand about VoIP phone systems in 2026 — hosted vs on-premises, features, PSTN switch-off migration, integration. Honest guidance from Telexico, a UK VoIP provider that migrates UK businesses every week.
What we hear every week.
The frustrations behind why businesses search for complete guide to voip phone systems in the first place. If any of these feel familiar, the fix is straightforward.
PSTN switch-off in 2027 is real and approaching
BT switches off ISDN and copper PSTN by January 2027 — many UK exchanges earlier. Every business on copper must migrate to VoIP. Not optional.
Confusion about hosted vs on-premises VoIP
Hosted VoIP runs in the cloud — no PBX hardware in your office. On-premises VoIP runs your own PBX. Both are VoIP; very different operational models.
Worry about number porting and migration disruption
Existing business numbers carry years of marketing equity. Number porting concerns stop businesses migrating. The actual process is routine and clean when project-managed properly.
Feature confusion — hunt groups, IVR, call recording, mobile apps
Modern hosted VoIP has many features; not all needed by every business; some confusingly named. Mapping features to operational needs matters.
VoIP phone systems — the practical landscape
**Hosted VoIP (cloud-based):** PBX functionality runs on the provider's cloud infrastructure; you have IP handsets and mobile/desktop apps on your end. No PBX hardware to maintain. Standard for UK SMEs in 2026. **On-premises VoIP:** PBX hardware lives in your office. More control, more maintenance burden. Less common for SMEs now; still relevant for some enterprise operations with specific requirements. **SIP trunks:** the carrier-grade connection between your VoIP platform and the wider phone network. Hosted VoIP includes SIP trunks; on-premises PBX needs them separately. **PSTN switch-off:** BT is switching off ISDN and copper PSTN by January 2027. All UK businesses on copper must migrate to VoIP. Telexico handles migration as a project with parallel running and scheduled cutover. **Microsoft Teams Phone:** Teams can make and receive UK landline calls via Direct Routing to a SIP provider (Telexico). Increasingly common for businesses standardised on Microsoft 365. **Features:** call recording, hunt groups, IVR menus, voicemail-to-email, mobile apps, hot-desking, multi-site routing, AI receptionist integration. Map to your operational needs rather than buying everything.
The Telexico approach to complete guide to voip phone systems.
Six things our customers consistently tell us matter.
Hosted VoIP standard for UK SMEs
Cloud-based, no PBX maintenance, modern feature set, mobile apps for hybrid working — fits most UK SME operations.
PSTN switch-off migration handled
Telexico migrates UK businesses from ISDN/PSTN to hosted VoIP every week — project-managed, parallel running, scheduled cutover, zero business disruption.
Mobile and desktop apps for hybrid working
Take office calls on mobile when out, work from home with full deskphone functionality — proper hybrid support.
Integration with CRM, calendar, AI receptionist
Standard integrations with most UK SME CRMs and calendar tools; AI receptionist sits in front of VoIP for inbound capture.
Often cheaper than ISDN it replaces
UK hosted VoIP typically £8-15 per user per month; ISDN line rental plus call charges often higher. Migration sometimes saves money monthly.
UK provider relationship
Telexico is UK-based ISP and VoIP provider — UK engineers, UK support, real ongoing relationship.
Built around UK SME operational reality
Most UK SMEs in 2026 are migrating from ISDN to hosted VoIP — forced by PSTN switch-off, also driven by feature uplift (mobile apps, call recording, AI integration) and often cost savings. Telexico has migrated hundreds of UK businesses already — converted offices, retail, hospitality, healthcare, manufacturing, multi-site. The migration is routine when project-managed; the operational uplift after is meaningful.
How it works for businesses like yours.
Three real-world setups we deliver across the UK.
SMEs migrating from ISDN before 2027
Project-managed migration from copper to hosted VoIP — typical 4-6 weeks, parallel running, scheduled cutover, number porting clean.
Multi-site businesses consolidating phones
Single hosted VoIP tenant across all UK sites — internal extension dialling, unified hunt groups, central reporting.
Microsoft 365 customers adding Teams Phone
Direct Routing via UK SIP (Telexico) — Teams makes and receives UK landline calls in the same interface used for chat and video.
Why this guide comes from Telexico
Telexico migrates UK businesses from ISDN to hosted VoIP every week and deploys hosted VoIP for new operations as part of the managed infrastructure stack. Wolverhampton-headquartered, UK engineers, UK support relationship.
What you actually get from Telexico.
Honest about scope. No aggressive sales tactics, no surprise renewal jumps, no tier-1 call-centre triage. Real UK engineers, transparent pricing, one provider relationship across the stack.
UK-based provider
Wolverhampton-headquartered. Engineers cover the West Midlands daily; UK-wide install via our partner network. Real UK engineer support, UK data residency, UK contractual relationship — not US-routed SaaS.
Real engineer support
When you call Telexico, you reach someone who can actually fix things. Response SLA backed by real engineering capacity rather than call-centre headcount. Named account manager for ongoing customers.
Free infrastructure review
Every engagement starts with a no-obligation audit of your current setup. Honest recommendation — sometimes that's "stay with your current provider after negotiation." We'd rather be honest than oversell.
Transparent pricing
What you sign for is what you pay — including renewal. No teaser pricing that jumps 30-100% at year two. No mid-contract CPI shock. Predictable multi-year cost from day one.
One provider, one platform
Broadband, hosted VoIP, business WiFi, AI Receptionist, 4G/5G failover, CCTV consolidated onto one Telexico relationship. Single bill, single support number, single engineer when something needs attention.
Migration project-managed
Switching to Telexico isn't DIY. We handle contract audit, notice timing, ordering, parallel running, cutover, old-provider close-out. Customer-visible disruption typically measured in minutes.
Tailored around your business.
Tell us what you have now and what's frustrating you. We'll come back with a tailored review of where we can simplify, consolidate or improve it — no fixed-package pressure, no hard sell.
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Frequently asked questions
What is VoIP and how does it differ from traditional phones?
VoIP (Voice over Internet Protocol) carries phone calls over the internet rather than traditional copper phone lines. Hosted VoIP runs the PBX functionality in the cloud — you have IP handsets and mobile/desktop apps. Traditional phones use copper lines into a physical PBX in your office. PSTN switch-off in 2027 forces UK businesses off traditional copper.
When do I have to migrate from ISDN?
Before your local Openreach exchange switches off PSTN. BT's deadline is January 2027 — many exchanges are switching off earlier. Check your specific exchange date; assume sooner rather than later. After your exchange switches off, ISDN service stops working.
Will VoIP work over my existing broadband?
Yes, if the broadband has enough upload bandwidth and decent latency. FTTP works very well (plenty of headroom). FTTC works for small operations but the upload limits multi-user VoIP. Telexico configures QoS on the managed router so voice traffic gets priority over other traffic. We assess your broadband during the migration design.
Can I keep my existing phone numbers?
Yes — number porting moves them across cleanly. All your existing UK numbers transfer to the hosted VoIP platform without changing stationery, marketing, Google listing or what customers dial. Porting takes 2-4 weeks lead time, scheduled cleanly with the cutover.
What features does hosted VoIP include?
Standard: call recording, hunt groups, voicemail-to-email, hold music, IVR menus, mobile/desktop apps, multi-site routing. Common extras: AI receptionist integration, CRM integration, hot-desking, call analytics, advanced call queues. Bundle features to match your operation rather than buying maximum.
How much does hosted VoIP cost?
Indicative UK SME: £8-15 per user per month for standard tier; £15-25 per user per month for premium with extra features. Plus the broadband it runs over. Plus optional one-off migration project fee. Often the all-in monthly cost is similar to or lower than the ISDN it replaces.
What about Microsoft Teams Phone?
Teams can make and receive UK landline calls via Direct Routing to a SIP provider (Telexico). Significantly cheaper than Microsoft's own Calling Plans for the same capability. Suits UK businesses already standardised on Microsoft 365. Setup is more technical than basic hosted VoIP — Telexico handles the configuration complexity.
Apply this to your business?
Reading the guide is one thing; applying it to your specific operation is another. Send us your current setup — we'll review what you have, what fits, and where to start. No hard sell, no fixed-package pressure.