VoIP Phone System for Business | The Essential Guide
Everything UK businesses need to know about VoIP phone systems in one place: how VoIP works, what features business systems include, pricing from £8–£25 per user per month, provider comparison, connectivity requirements, and step-by-step migration guidance.
Matt Cannon
Managing Director
The Essential VoIP Guide for UK Businesses
This guide is designed for business owners and decision-makers who want a comprehensive, practical understanding of business VoIP — from the technology fundamentals through to provider selection and migration planning. It covers every question we regularly encounter from businesses evaluating the switch.
What Is VoIP?
VoIP (Voice over Internet Protocol) transmits telephone calls as digital data over an internet connection rather than as analogue signals over copper telephone wires. When you speak into a VoIP phone, your voice is converted to data packets, transmitted over the internet, and reassembled at the destination. The process happens in real time, with imperceptible delay on a good connection.
A business VoIP phone system — also called a hosted PBX or cloud phone system — adds all the call management functionality of a traditional office telephone system (call routing, extensions, voicemail, auto-attendant) to the underlying VoIP technology, delivered as a cloud service.
Why VoIP Is Replacing Traditional Phone Systems
Three forces are driving the transition from PSTN/ISDN to VoIP:
- PSTN switch-off: BT Openreach is retiring the copper telephone network. All UK businesses must migrate to IP telephony.
- Cost advantage: VoIP at £8–£18/user/month is typically 40–60% cheaper than equivalent PSTN/ISDN costs.
- Feature advantage: Hosted VoIP includes capabilities (call analytics, CRM integration, mobile working, call recording) that traditional PBX systems cannot match without expensive add-ons.
Business VoIP Features
Standard Features (All Tiers)
Auto-attendant, hunt groups, call transfer, voicemail to email, hold music, conference calling, internal extension dialling, call forwarding.
Mid-Tier Features
Call recording, advanced analytics, CRM integration (Salesforce, HubSpot, Dynamics), Microsoft Teams integration, call queuing, IVR menus.
Enterprise Features
Contact centre capability, real-time wallboards, supervisor monitoring and whisper, API access, AI-powered call analytics, unlimited international calling.
VoIP Pricing Guide
- Entry (£8–£12/user/month): Core calling, voicemail, basic routing. For businesses needing a simple cloud phone system.
- Mid (£12–£18/user/month): Full feature set including recording, analytics, CRM integration. Suits most UK SMEs.
- Enterprise (£18–£25/user/month): Contact centre, AI features, API. For businesses with customer service operations.
Hardware: IP desk phones £80–£200. Softphone apps: included. Mobile apps: included.
Internet Connectivity for VoIP
VoIP calls use approximately 100 kbps each way. Ten concurrent calls need 1 Mbps dedicated to voice. Low latency (below 150 ms) and low jitter are more important than raw speed. Business-grade FTTP is adequate for most SMEs. A leased line provides dedicated bandwidth and SLA-backed performance for business-critical deployments.
Choosing a VoIP Provider
Key criteria: feature set (vs. your requirements), pricing (full contract term, not just headline), uptime SLA (99.9%–99.999%), support quality (UK-based, response time), and integration capability. The leading providers for UK businesses:
- Gamma Horizon: £12–£18/user/month. Carrier-grade, UK-backed. Best for managed SME service.
- 3CX: From £8/user/month. Best value, flexible deployment. Requires IT management.
- Teams Phone: £11–£21/user/month. Best for Microsoft 365 users.
- RingCentral: £15–£25/user/month. Best integration library.
- 8x8: £12–£20/user/month. Best contact centre features.
Migration Planning
A successful VoIP migration requires: telephony audit (all lines and dependencies), connectivity assessment, provider selection and configuration, number porting (5–10 working days), hardware provisioning, secondary line migration (alarms, lifts, fax), and go-live testing. Most SME migrations complete within 2–3 weeks when properly managed.
Common Migration Mistakes
- Overlooking secondary lines (alarms, lifts, payment terminals)
- Porting numbers before the new system is tested and ready
- Not testing call quality on the live connection before porting
- Underestimating training time for staff unfamiliar with VoIP softphone apps
- Choosing a provider based on price alone without verifying feature coverage
AMVIA manages the complete VoIP journey for UK businesses — from initial assessment through to go-live and ongoing support. Contact us for a free telephony review.
Ready to Move to Business VoIP?
AMVIA handles the complete VoIP migration process for UK businesses — from provider selection to number porting and go-live support.
Frequently Asked Questions
A traditional PBX is physical hardware installed on your premises. It connects to the telephone network via ISDN or PSTN lines. A VoIP phone system uses cloud-based software in the provider's data centre, connected via the internet. VoIP eliminates on-site hardware, reduces maintenance costs, and adds features and scalability that traditional PBX cannot match.
Existing analogue phones can connect to a VoIP system through an analogue telephone adaptor (ATA), costing approximately £30–£80. IP phones (purpose-built for VoIP) provide better functionality and cost £80–£200 each. Softphone apps on laptops and mobiles eliminate hardware cost entirely. The right choice depends on your team's working style.
Reputable VoIP providers use TLS (Transport Layer Security) and SRTP (Secure Real-Time Transport Protocol) to encrypt calls in transit. As with any internet-connected service, best security practice includes strong admin portal passwords, restricted access to VoIP configuration, and firewall rules that limit SIP traffic to your provider's IP ranges.
A VoIP auto-attendant is a virtual receptionist that answers calls automatically, plays a customisable greeting, and routes callers based on their dial input. For example: 'Welcome to Acme Ltd. Press 1 for sales, 2 for support, or hold for reception.' Callers are connected to the appropriate extension, hunt group, or voicemail based on their selection.
VoIP is the broad term for transmitting voice over IP networks. SIP (Session Initiation Protocol) is the specific signalling protocol used by most VoIP systems to initiate, manage, and terminate calls. When people talk about SIP phones or SIP trunks, they are referring to VoIP equipment and services using the SIP protocol.
Yes. Call queuing is a standard feature of most hosted VoIP plans. When all agents or extensions are busy, new inbound calls are placed in a queue with configurable hold music and position announcements. Queue analytics track wait times and abandonment rates, helping businesses manage staffing levels effectively.
Related Reading
VoIP Phone System for Business | AMVIA Guide 2025
The definitive guide to VoIP phone systems for UK businesses — features, providers, and migration.
VoIP Phone Systems for Small Businesses | UK Guide
Best VoIP options for small UK businesses — budget-friendly with professional features.
PSTN Switch-Off | How to Migrate Your Business to VoIP
A step-by-step guide to planning your business's migration from PSTN to VoIP.