Comparison of the Top UK VoIP Providers | AMVIA 2025
The leading UK VoIP providers for business in 2025 are Gamma Horizon, RingCentral, 3CX, Microsoft Teams Phone, 8x8, and Vonage. This side-by-side comparison covers pricing, features, uptime, support quality, and which provider suits which business profile.
Nathan Hill-Haimes
Technical Director
How UK VoIP Providers Compare
The UK hosted VoIP market is competitive, which is good news for businesses. Pricing has fallen and feature sets have broadened considerably in recent years. The challenge is not finding a VoIP provider — it is identifying which one fits your business. This comparison covers the six providers most frequently considered by UK SMEs and mid-market businesses.
Gamma Horizon
Type: Carrier-grade hosted PBX. Reseller-delivered.
Pricing: £12–£18 per user per month
Uptime SLA: 99.99%
Key features: Auto-attendant, hunt groups, call recording, advanced analytics, Teams integration, voicemail to email, mobile and desktop apps
Support: Delivered through accredited reseller partners with UK carrier backing
Best for: UK SMEs and mid-market businesses wanting a managed, reliable hosted phone system. Gamma's carrier-grade infrastructure makes it one of the most dependable platforms in the UK market.
RingCentral
Type: UCaaS (unified communications). Direct and reseller.
Pricing: £15–£25 per user per month
Uptime SLA: 99.999% (five nines)
Key features: VoIP, video meetings, team messaging, 250+ integrations, advanced analytics, contact centre add-on
Support: 24/7 US-based support with UK business hours coverage
Best for: Businesses requiring deep third-party integrations (CRM, helpdesk, ERP) and those wanting a single platform for all communications. Premium pricing reflects the enterprise feature set.
3CX
Type: Software PBX. Cloud, hosted, or on-premise.
Pricing: £8–£14 per user per month (cloud hosted)
Uptime SLA: Dependent on hosting provider
Key features: Full PBX features, video conferencing, web client, mobile apps, CRM integrations, call centre
Support: Via resellers and community. Direct support available on higher tiers.
Best for: IT-managed businesses or those with a managed IT provider. Lower pricing at scale; strong feature depth. Requires more active management than fully managed hosted services.
Microsoft Teams Phone
Type: Add-on to Microsoft 365. Direct Microsoft licensing.
Pricing: £6–£12 per user per month (licence) + £5–£9 per user per month (calling plan or direct routing)
Uptime SLA: 99.9% (backed by Microsoft)
Key features: External PSTN calling through Teams, call queues, auto-attendant, call recording, voicemail, full M365 integration
Support: Via Microsoft or Microsoft partners
Best for: Businesses already on Microsoft 365 who want to use Teams as their phone system. Eliminates the need for a separate VoIP platform.
8x8
Type: UCaaS. Direct and reseller.
Pricing: £12–£20 per user per month
Uptime SLA: 99.999%
Key features: VoIP, video, team messaging, contact centre, AI-powered analytics, unlimited calling to 40+ countries
Support: 24/7 via phone, chat, and email
Best for: Businesses with customer service or contact centre operations. 8x8's contact centre features are well regarded, and the unlimited international calling is valuable for businesses with global operations.
Vonage
Type: UCaaS with API platform. Direct and reseller.
Pricing: £10–£20 per user per month
Uptime SLA: 99.999%
Key features: VoIP, video, team messaging, developer API suite, SMS capabilities
Support: 24/7 with UK office
Best for: Businesses that want to build custom communications integrations using Vonage's API. Competitive for standard business VoIP use, but the API capability is the real differentiator.
Which Provider Should You Choose?
- Managed reliability for UK SME: Gamma Horizon
- Cost efficiency: 3CX or Microsoft Teams Phone
- Deep integrations: RingCentral
- Microsoft 365 alignment: Teams Phone
- Contact centre: 8x8 or RingCentral Contact Centre
- Developer/API: Vonage
AMVIA provides independent comparison for UK businesses across all these platforms — with no commercial preference. We'll identify the right fit based on your requirements, not our margins.
Which VoIP Provider Fits Your Business?
Tell AMVIA about your requirements and we'll compare the leading UK providers — with pricing, feature comparisons, and an honest recommendation.
Frequently Asked Questions
RingCentral, 8x8, and Vonage all publish 99.999% uptime SLAs. Gamma Horizon publishes 99.99%. Microsoft Teams Phone carries Microsoft's 99.9% SLA. In practice, all major providers have excellent reliability — the practical difference between 99.99% and 99.999% is less than an hour of downtime per year.
Gamma Horizon is typically a better fit for UK-centric SMEs wanting a carrier-grade managed service at a lower price point. RingCentral is more compelling for businesses that need deep integrations with CRM and other enterprise software, or those with significant international operations. The best choice depends on your specific requirements.
Technically yes, but it creates management complexity. Most businesses benefit from a single VoIP platform across all sites, managed through one portal. If you have specific location requirements, a provider like Gamma that supports multi-site deployments natively is a better choice than mixing platforms.
Microsoft Teams Phone is arguably the simplest if you already use Microsoft 365 — it is configured through the familiar Microsoft admin centre. For standalone VoIP, Gamma Horizon (via a reseller like AMVIA) provides a fully managed setup experience. 3CX requires more configuration but provides a richer deployment toolkit.
Yes. Most providers offer 12-month, 24-month, and rolling monthly options. Rolling monthly contracts carry a premium of typically 10–20% over annual terms. For businesses that value flexibility over cost optimisation, monthly rolling contracts are available from most major providers.
Support quality varies. Gamma Horizon support is typically handled through the reseller, providing a direct account management relationship. RingCentral and 8x8 offer 24/7 global support with UK business hours coverage. Microsoft support is available via partners. For SMEs, working through a managed IT provider like AMVIA typically provides a better support experience than dealing directly with large providers.
Related Reading
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UK VoIP Provider Comparison | Business Plans & Pricing
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Choosing the Best Business VoIP Providers | Buyer's Guide
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