A business phone system cost calculator estimates the total expense of deploying VoIP, hosted PBX, or on-premise telephony across your organisation based on user count, features, and contract terms. UK businesses typically pay between £8 and £25 per user per month for cloud-based VoIP, rising to £15 to £35 per user per month for a fully managed hosted PBX with advanced call routing and CRM integration. On-premise systems require a one-off capital investment of £2,000 to £10,000 depending on capacity, plus ongoing maintenance costs of approximately £500 to £1,500 per year. For a 20-person office, annual phone system costs range from roughly £1,920 on a basic VoIP plan to £8,400 on a feature-rich hosted solution. By entering your team size and required features into this calculator, you can compare deployment models side by side and understand the true three-year cost of ownership for each option.
Business Phone System Costs by Number of Users
The table compares monthly and annual costs for VoIP vs traditional phone systems at common team sizes.
| Users | VoIP/month | Traditional/month | VoIP/year | Annual Saving |
|---|---|---|---|---|
| 5 | £60 | £175 | £720 | £1,380 |
| 10 | £120 | £350 | £1,440 | £2,760 |
| 20 | £220 | £650 | £2,640 | £5,160 |
| 50 | £500 | £1,500 | £6,000 | £12,000 |
| 100 | £900 | £2,800 | £10,800 | £22,800 |
Based on average UK provider pricing 2025/26. VoIP assumes cloud-hosted; traditional assumes PBX lease + line rental.
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How to Use This Calculator
Enter the number of users — count every employee who needs a phone extension, including remote workers who will use mobile or softphone apps.
Select your preferred system type — choose between VoIP, hosted PBX, or on-premise to compare pricing models.
Choose your required features — tick the features you need such as call recording, auto-attendant, CRM integration, or video conferencing.
Review your cost breakdown — see monthly per-user costs, one-off setup fees, hardware costs, and projected three-year total cost of ownership.
UK businesses typically pay £8–£25 per user per month for VoIP phone systems, compared to £25–£45 per line for traditional systems. Most businesses save 40–60% by switching to VoIP, with the ISDN/PSTN switch-off in January 2027 making the transition essential.
Enter three key details about your business: total number of phone users (including remote workers), average monthly call volume per user (light = <2 hours, medium = 2–5 hours, heavy = 5+ hours), and percentage of workers who need mobile/remote access. The calculator compares VoIP and traditional system costs side-by-side, showing your potential savings.
VoIP vs Traditional Phone Systems: Cost Breakdown
Understanding the cost structure of each phone system type is essential for making an informed decision. While traditional systems and VoIP solutions both enable business calling, their pricing models, infrastructure requirements, and included features differ substantially—and these differences directly impact your monthly expenditure.
VoIP (Cloud-Based) Costs
VoIP systems charge on a per-user basis, typically ranging from £8 to £25 per user per month depending on the provider and feature tier. This pricing usually includes unlimited UK landline minutes (some providers cap at 3,000–5,000 minutes per user), a generous mobile minute allowance, and a comprehensive feature set that would cost hundreds extra on traditional systems.
The hardware requirements for VoIP are minimal. Most businesses use softphones—software applications installed on existing computers, laptops, tablets, or smartphones. This eliminates the need for dedicated desk phones entirely, though you can purchase IP phones (£50–£200 per handset) if preferred. Setup is typically handled remotely by the provider at no additional cost, with most businesses operational within 24–48 hours of signing up.
Standard features included in most VoIP packages include: voicemail-to-email transcription, call forwarding and routing, video conferencing (often up to 100 participants), mobile apps for iOS and Android, desktop softphone clients, call analytics and reporting, auto-attendant/IVR systems, and integration with common business tools like Microsoft Teams or Slack. Leading UK VoIP providers include 8×8, RingCentral, 3CX, Vonage Business, and Gamma Horizon.
Traditional (On-Premise) Costs
Traditional phone systems operate on a fundamentally different cost structure. Line rental from BT or other carriers typically costs £15–£25 per line per month, before you’ve made a single call. Call charges are then added on top: approximately 1–3p per minute for UK landlines and 5–10p per minute for UK mobiles. For businesses making significant volumes of mobile calls, these charges accumulate rapidly.
The capital expenditure requirements are substantial. A PBX (Private Branch Exchange) system—the hardware that routes calls within your office—costs between £1,500 for a basic 5-line system and £5,000+ for enterprise-grade equipment supporting 50+ lines. Desk phones cost £80–£150 per handset, and installation typically requires an engineer visit charged at £200–£500.
Ongoing maintenance contracts add £200–£500 annually for basic support, with emergency callout charges often exceeding £150 per visit. Features that come standard with VoIP—such as call recording, voicemail-to-email, or mobile integration—require expensive add-on modules or simply aren’t available at any price. When the PBX hardware fails (typical lifespan 7–10 years), replacement costs must be factored into long-term planning.
Hybrid Systems
Hybrid phone systems combine elements of both approaches, typically using an on-premise PBX connected to the outside world via SIP trunking rather than traditional phone lines. This configuration costs less than pure traditional systems (SIP trunks are cheaper than ISDN lines) while allowing businesses to retain existing PBX investments. However, hybrid systems still require hardware maintenance and lack many of the advanced features available in full cloud VoIP platforms. They’re best suited as a transitional solution for businesses with recent PBX investments who aren’t ready for a complete cloud migration.
Key Features That Affect Phone System Costs
Call recording typically adds £2–£5 per user monthly on VoIP systems (or £500+ as a hardware add-on for traditional systems). CRM integration is usually restricted to premium VoIP tiers (£20+/user) and unavailable on traditional systems. Video conferencing comes standard with most VoIP plans but requires separate platforms like Zoom or Microsoft Teams with traditional phone systems.
The features included in your phone system significantly impact both monthly costs and operational efficiency. Understanding which capabilities come as standard, which require premium tiers, and which aren’t available at all helps you choose the right system for your business needs.
Call recording is essential for businesses in regulated industries (financial services, insurance, legal) or those focused on quality assurance and training. On VoIP systems, call recording typically costs £2–£5 per user per month as an add-on feature, with recordings stored in the cloud and accessible via web portal. Some premium VoIP plans include call recording as standard. On traditional systems, call recording requires dedicated hardware costing £500–£1,500 upfront, plus ongoing maintenance costs.
CRM integration—the ability to automatically log calls, click-to-dial from customer records, and display caller information from your CRM system—is restricted to premium VoIP tiers from providers like RingCentral or 8×8. These integrations typically require the £20–£30 per user monthly plans and work with popular platforms including Salesforce, HubSpot, Zoho, and Microsoft Dynamics. Traditional phone systems offer no CRM integration capability regardless of price.
Auto-attendant and IVR (Interactive Voice Response) systems—the “Press 1 for Sales, Press 2 for Support” menus—come standard with virtually all VoIP systems, even entry-level plans. You can typically configure unlimited menus and routing rules through a web interface. On traditional systems, auto-attendant functionality requires hardware add-on modules costing £500–£1,000, with complex routing often requiring professional programming services.
Video conferencing is included in most modern VoIP systems, supporting anywhere from 25 to 500 participants depending on the plan. This eliminates the need for separate Zoom or Microsoft Teams subscriptions for many businesses. Traditional phone systems offer no video capability—you must purchase and manage separate video conferencing platforms.
Mobile apps and softphones are standard features of VoIP systems, allowing employees to make and receive calls on their business number from any device, anywhere with internet connectivity. This capability has become essential for remote and hybrid working models. Traditional phone systems require expensive call forwarding or separate mobile contracts to achieve similar functionality, typically costing £5–£10 per user monthly in additional charges.
The ISDN Switch-Off: What UK Businesses Must Know
January 2027 marks the final shutdown of the UK’s PSTN (Public Switched Telephone Network) and ISDN (Integrated Services Digital Network) infrastructure. Openreach, which manages the physical network used by BT and most other UK telecoms providers, will completely cease supporting these legacy technologies. This affects more than 2 million business phone lines currently operating on traditional systems across the UK.
This isn’t a voluntary upgrade—it’s a mandatory infrastructure change. After January 2027, traditional phone systems simply won’t function. Businesses that haven’t migrated will lose all phone connectivity on the cutoff date. While the deadline was originally set for December 2025, Ofcom granted a one-year extension following industry concerns about migration capacity. However, January 2027 is now a firm deadline with no further extensions planned.
Businesses migrating early benefit from better pricing, more provider choice, and minimal business disruption. As the deadline approaches, suppliers face capacity constraints—engineer availability for site surveys and installations becomes limited, equipment stock depletes, and providers prioritise enterprise customers over smaller businesses. Additionally, early movers avoid the inevitable price increases that occur when suppliers face overwhelming demand with limited time to deliver.
The migration process typically takes 4–8 weeks from initial consultation to full deployment, depending on business size and complexity. For businesses with multiple sites, complex call routing requirements, or integration needs with existing systems, migration can take 12+ weeks. Waiting until late 2026 risks missing the deadline entirely, leaving your business without phone connectivity at the most critical juncture. Most telecoms consultants now recommend completing migration by Q3 2026 at the latest.
VoIP phone systems cost 40-60% less than traditional landlines and include features (call recording, auto-attendant, CRM integration) that would cost £50-£100 per user extra on legacy systems.
Our Methodology
This calculator is built on extensive research into UK business telecoms pricing, combining data from multiple authoritative sources to provide accurate cost comparisons. We analysed published rate cards from the UK’s leading VoIP providers (8×8, RingCentral, 3CX, Vonage Business, Gamma Horizon) and traditional telecoms carriers (BT Business, TalkTalk Business, Daisy Communications), verified against Ofcom’s annual Business Connectivity Market Review and UK Business Telecommunications Survey data.
The cost calculations factor in realistic usage patterns based on Ofcom research showing UK businesses average 45–90 minutes of outbound calling per user daily, with approximately 60% of calls to UK landlines and 40% to UK mobiles. We’ve included both the obvious costs (per-user fees, line rental, call charges) and frequently overlooked expenses (hardware depreciation, maintenance contracts, engineer callouts, feature add-ons) to ensure the total cost of ownership comparison reflects real-world expenditure. All pricing is verified against live provider quotes and updated quarterly to reflect current market rates.
For more detailed information on business phone system costs and choosing the right solution for your needs, see our comprehensive guide to business phone system costs in the UK. You can also explore other cost calculators in our business tools section, or browse all telephone system guides in our phone systems hub.
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