VoIP (Voice over IP) replaces traditional phone lines with internet-delivered calls — typically cheaper, more flexible, and feature-rich. UK SMEs choosing VoIP should weigh call quality, integration with their CRM and other tools, mobile app capability, and whether they want a hosted PBX (BryxoPhone, RingCentral, 8x8) or a unified-comms suite (Microsoft Teams Phone, Google Voice).

The UK PSTN switch-off (originally December 2025, now extended to January 2027) is forcing every business still on copper-based phone lines to move. If you haven''t made the switch, this is the year.

What VoIP gives you

Compared with traditional landline PBX:

Lower per-line cost: typically £5-£15/seat/month vs £15-£40 for legacy PBX with line rentals.
Free or near-free internal calls across all extensions, regardless of physical location.
Mobile and desktop apps — your business number on any device.
Call recording baked in (compliance permitting).
IVR and call routing without expensive on-premise hardware.
CRM integration — caller name pops up from your CRM, calls log automatically.
Easy scaling — add a seat in minutes, not weeks.

The trade-off: VoIP depends on your internet connection. A poor or unreliable connection = poor call quality. Plan accordingly.

The two main UK VoIP categories

Hosted PBX (traditional business phone)

Examples: BryxoPhone, RingCentral, 8x8, Vonage, Dialpad, Yay.com.

Best for: businesses that primarily make and receive external calls. Strong call-handling features, IVR, hunt groups, call queues, recording.

Unified communications

Examples: Microsoft Teams Phone, Google Voice (with calling), Zoom Phone.

Best for: businesses already heavily on Microsoft 365 or Google Workspace. Phone is one feature alongside chat, video, file sharing.

For sales-heavy businesses, hosted PBX usually wins on call-handling features. For most other SMEs, unified comms wins on simplicity (one platform, one bill, one app).

Buying criteria that matter

1. Call quality

Check the codec (G.722 or Opus is HD; G.711 is the legacy standard). Test on a 2-week trial with real calls before committing. Quality varies by carrier interconnect, not just by software.

2. Number portability

You should be able to port your existing UK landline number into VoIP. Some providers charge for porting; most include it. Check.

3. UK presence

Some VoIP providers are US-based with UK numbers. Customer service hours, call routing, and tax compliance can be issues. For most SMEs, a UK-based provider is the right call.

4. CRM and tool integration

Native integrations with your CRM, helpdesk, accounting tool. Test on the trial.

5. Mobile app

Field-heavy or remote-heavy businesses live on mobile. The mobile app quality varies massively. Pick one that genuinely works on the road.

6. Call recording and compliance

If you''re in a regulated industry or want recording for QA, check: is recording per-call or always on, is it stored in the UK/EU, is consent capture handled, and can you search recordings later?

7. Pricing model

Per-seat is the standard. Watch for: minimum seat counts, contract lengths, "user" vs "device" definitions, international call costs, overage charges on bundled minutes.

The PSTN switch-off context

Openreach''s PSTN switch-off ends traditional copper-based voice service in the UK. Original target: December 2025. Now extended (with phased regional withdrawals) to January 2027 for most areas.

If your business is still on:

Traditional ISDN/PSTN landline: must switch to VoIP (or All-IP equivalent) before your area''s migration date.
Single broadband line + landline phone: typically affected — the landline service is going.
Card payment terminals, fax machines, monitored alarms on phone lines: also affected — check your specific equipment.

Don''t wait. By Q3 2026, switching demand will exceed installation capacity in many areas.

Common UK SME setup

For most service businesses at 5-30 employees:

Hosted PBX VoIP (~£10-£15/seat/month).
Each user gets a softphone app on desktop + mobile + (optionally) a desk phone.
Main inbound number with a simple IVR ("press 1 for sales, 2 for support, 0 to speak to anyone").
Hunt group for sales/support to ring multiple devices.
CRM integration so calls log automatically.
Call recording on all calls, retained for 6 months.

Typical cost: £100-£500/month for an SME with 10-30 seats.

What to do this month

Check your current phone service against PSTN switch-off dates. Confirm your migration deadline.
If you''re still on legacy: start a VoIP trial this month. Test with 2-3 providers across 2 weeks each.
Verify: number porting, CRM integration, mobile app quality, call quality on your actual office internet.
Plan the cutover for a low-traffic week — typically late July, December, or a quiet Friday-Monday.

VoIP for business: what to consider