Top 5 UK Business VoIP Providers | AMVIA Comparison

How AMVIA Ranks UK VoIP Providers

This ranking is based on AMVIA's direct experience deploying and supporting VoIP systems for UK SMEs, combined with ongoing evaluation of provider pricing, feature development, reliability records, and support quality. The ranking reflects overall value for UK business users — not just headline pricing or feature lists.

1. Gamma Horizon — Top Choice for UK SMEs

Overall score: 9/10

Gamma Horizon consistently earns the top position for UK SMEs. Its Cisco Broadworks infrastructure delivers carrier-grade reliability with a published 99.99% uptime SLA. The feature set covers everything an SME needs, and the reseller delivery model means businesses get genuine account management rather than a helpline number.

Strengths: UK carrier infrastructure, comprehensive features, excellent reseller support network, competitive pricing at £12–£18/user/month.

Limitations: Not available direct — must be purchased through a reseller. Less well-known brand than US UCaaS platforms.

Best for: UK businesses of 5–200 users wanting managed, reliable hosted telephony.

2. 3CX — Best Value

Overall score: 8.5/10

3CX delivers an exceptional feature-to-price ratio. Starting at around £8/user/month for hosted deployments, it is one of the most cost-effective platforms available. Full feature depth including video, web client, mobile apps, and CRM integrations. The open SIP architecture integrates with a wide range of handsets and carriers.

Strengths: Lowest cost of ownership, flexible deployment, full feature depth, open standards.

Limitations: Requires IT capability to configure and manage. Less polished UX than some UCaaS platforms. Support through resellers rather than a direct consumer experience.

Best for: IT-managed businesses wanting maximum features at the lowest cost.

3. Microsoft Teams Phone — Best for Microsoft 365 Users

Overall score: 8.5/10

For businesses already using Microsoft 365, Teams Phone is compelling. It consolidates all communications — calls, chat, video, files — in a single interface that staff already use. The licensing model makes it cost-effective for Microsoft 365 subscribers, and the M365 integration depth is unmatched.

Strengths: Single interface for all communications, deep M365 integration, competitive total cost, Microsoft's global infrastructure.

Limitations: Teams interface may not suit all working styles. Calling plan minutes can be limiting for high call volumes. Less flexible for non-Microsoft ecosystems.

Best for: Businesses on Microsoft 365 Business Premium, E3, or E5.

4. RingCentral — Best for Enterprise Integrations

Overall score: 8/10

RingCentral's 250+ integration library and enterprise-grade feature set make it the right choice for businesses where deep CRM and business application integration is a priority. Five-nines uptime SLA and mature global infrastructure. Higher pricing reflects the enterprise positioning.

Strengths: Largest integration library, five-nines SLA, mature platform, strong global footprint.

Limitations: Higher pricing (£15–£25/user) than competitors. Feature complexity may be unnecessary for straightforward SME use cases.

Best for: Businesses with significant CRM integration requirements or international operations.

5. 8x8 — Best for Contact Centre

Overall score: 8/10

8x8 scores highly for contact centre capability within the standard UCaaS platform, and its unlimited international calling on X4 and above plans is a genuine differentiator for businesses with global customer contact. Analytics are detailed and the supervisor tooling is well-regarded.

Strengths: Strong contact centre features, unlimited international calling, detailed analytics, five-nines SLA.

Limitations: Less well-known in the UK SME market than the top three. Some users find the interface less intuitive than competitors.

Best for: Businesses with customer service teams, contact centre requirements, or significant international calling volumes.

Summary Guidance

For most UK SMEs evaluating VoIP for the first time: start with Gamma Horizon (via a reseller) and Teams Phone if you use Microsoft 365 — these two cover the vast majority of UK business scenarios at competitive price points.