VoIP Phone System Vendor Comparison | UK Business Guide
Comparing VoIP vendors for UK businesses requires evaluating features, pricing, SLAs, and implementation support together. This guide compares Gamma Horizon, 3CX, RingCentral, Microsoft Teams Phone, and 8x8 across these dimensions — with honest assessments of strengths, limitations, and best-fit profiles.
Nathan Hill-Haimes
Technical Director
Vendor Comparison: Why It Matters
Choosing a VoIP vendor is a multi-year commercial commitment. The platform you select will handle your business's communications — a function as critical as email. Getting the vendor comparison right, considering all relevant dimensions rather than just headline price, is worth the investment of time.
Vendor 1: Gamma Horizon
Product Type
Carrier-grade hosted PBX. UK-native infrastructure. Reseller-delivered only (not direct to business).
Features
Comprehensive: auto-attendant, hunt groups, call recording, analytics, Teams integration, voicemail to email, mobile and desktop apps, conference bridges, CRM integration tools.
Pricing
£12–£18 per user per month. Typically includes unlimited UK landline and mobile calls. Number rental included; international call charges apply.
SLA
99.99% uptime. Credit-based remedies for SLA failures.
Implementation
Managed by accredited resellers. Typical deployment 1–2 weeks including number porting. Full configuration and testing included in managed service delivery.
Support
Via reseller with UK carrier backing. Account management relationship with reseller. Escalation to Gamma carrier for network issues.
Verdict
Best overall choice for UK SMEs wanting a fully managed, reliable hosted phone system. The reseller model provides better account management than direct purchasing for most businesses.
Vendor 2: 3CX
Product Type
Software PBX. Cloud, private cloud, or on-premise deployment.
Features
Full PBX features plus video conferencing, web client, mobile apps, and extensive CRM integrations. Open SIP architecture supports wide range of endpoints.
Pricing
From £8/user/month (hosted, annual). SIP carrier costs separate (typically £3–£8/user/month additional for calls).
SLA
Dependent on hosting provider. Typically 99.9%+ on reputable cloud hosts.
Implementation
Requires configuration — either by an IT team or a managed IT provider. Deployment typically 1–3 weeks depending on complexity. Well-documented setup process.
Support
Via resellers, certified partners, and community. Higher tiers include direct support access.
Verdict
Best value for IT-managed businesses. Lowest total cost of ownership at most user counts, with full feature depth.
Vendor 3: RingCentral
Product Type
UCaaS platform. Direct and reseller.
Features
VoIP, video, team messaging, 250+ integrations. Advanced analytics, contact centre add-on. AI features on higher plans.
Pricing
£15–£25 per user per month.
SLA
99.999% uptime.
Implementation
Self-service with professional services option. Typically 2–4 weeks for full deployment with integrations configured.
Support
24/7 global support. UK account management on mid-market and enterprise plans.
Verdict
Premium pricing justified for businesses with deep integration requirements. Higher price than necessary for standard SME use without integration complexity.
Vendor 4: Microsoft Teams Phone
Product Type
Microsoft 365 add-on. Licensed through Microsoft or Microsoft partner.
Features
Full PSTN calling via Teams interface. Call queues, auto-attendant, call recording (Premium), voicemail, analytics. Native M365 integration.
Pricing
£6–£12/user/month licence + £5–£9/user/month calling plan. Total £11–£21/user/month.
SLA
99.9% uptime (Microsoft).
Implementation
Via Microsoft admin centre or partner. Number porting through Microsoft or carrier. Typically 1–3 weeks deployment.
Support
Via Microsoft or Microsoft partner.
Verdict
Compelling for Microsoft 365 users. Strong total cost value when M365 subscription is already in place.
Vendor 5: 8x8
Product Type
UCaaS platform. Direct and reseller.
Features
VoIP, video, messaging, analytics, contact centre (X6+). Unlimited international calling on X4+.
Pricing
£12–£20/user/month (X2–X4).
SLA
99.999% uptime.
Implementation
Self-service with professional services option.
Support
24/7 support with UK coverage.
Verdict
Strong choice for contact centre use cases and businesses with high international calling volumes.
Which Vendor Wins for Your Business?
AMVIA provides free, structured VoIP vendor comparisons based on your specific requirements — with current pricing and feature mapping for all five platforms.
Frequently Asked Questions
A VoIP vendor creates and maintains the underlying platform (Gamma, 3CX, RingCentral). A reseller sells and supports the vendor's platform to end businesses, often adding managed setup, training, and ongoing support. For SMEs, buying through a reseller typically provides better account management than buying direct from the vendor.
3CX and Gamma Horizon offer the strongest feature-to-price ratio for UK SMEs. 3CX is the most feature-rich at the lowest price; Gamma provides a more managed experience with carrier-grade reliability. For Microsoft 365 users, Teams Phone is compelling. The best choice depends on your specific feature requirements and IT management capability.
Standard VoIP vendor contracts are 12 or 24 months. Monthly rolling options are available at a premium. Microsoft Teams Phone licensing follows Microsoft's standard annual commitment. Review the auto-renewal clause and notice period carefully — most contracts require 30–90 days' notice before term end to avoid automatic renewal.
Most vendors and resellers include basic user training as part of setup. More comprehensive training — covering advanced features, call routing configuration, and analytics — is typically available as a paid professional service. AMVIA includes user onboarding and portal training as standard in VoIP deployments for clients.
Regulated industries (financial services, legal, healthcare) should verify that their chosen VoIP vendor meets specific compliance requirements: call recording with tamper-evident storage, data residency controls, GDPR compliance, and audit trail capability. All five vendors in this comparison offer compliance-grade options, but the specific configuration must be verified against your regulatory requirements.
A vendor RFP should request: detailed pricing including all components, SLA documentation and credit terms, feature matrix against your requirements, implementation timeline and process, support structure and escalation paths, data residency and compliance documentation, and customer references from similar-sized businesses. AMVIA can assist with this process for UK businesses.
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