Rates and data last verified 17 February 2026 by the ExpertSure editorial team. Sources are listed in the methodology below the calculator.
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.
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- Unlimited-calling plans cost £13.95 to £18 per user a month - bOnline starts at £13.95, Vonage Core is £15, NBC Cloud Voice Enterprise starts at £17.99 and BT Digital Voice Enhanced is £18, all before VAT
- BT’s per-user price rises £1 every April - Digital Voice Enhanced goes from £18 to £19 on 1 April 2027 and £20 in 2028, so ten users pay £2,160 a year now and £2,400 from April 2028
- Some features come inside the base price - bOnline’s £13.95 plan includes on-demand call recording and Vonage’s £15 Core plan includes CRM integration and Microsoft Teams compatibility, so check each tier before paying for extras
- The copper phone network closes on 31 January 2027 - Openreach says all traditional lines must move to a digital service by then, and ISDN services that have not been migrated will be ceased
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.
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. At the calculator’s defaults the recurring saving from VoIP is about 48% for ten users, but that rests on assumed traditional line costs, so enter the prices you actually pay. Openreach’s switch-off of traditional lines on 31 January 2027 means most businesses must move to a digital service anyway.
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 (some entry plans, such as RingCentral Essentials, exclude multi-level IVR), 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 included on some mid-priced VoIP plans, such as Vonage’s £15 Core plan, 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 plans include call recording as standard, such as bOnline’s £13.95 Unlimited Calling plan. 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 often kept for higher VoIP tiers, but not always: Vonage’s £15 Core plan includes it. These integrations 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 isn’t a voluntary upgrade. Openreach says all traditional phone lines need to move to a digital service by 31 January 2027, and ISDN services that have not been migrated will be ceased; a business that has not moved may be put on an emergency voice-only service or lose service altogether. The original target was December 2025. Government guidance says most customers are expected to have switched by the end of January 2027, though some providers’ timetables differ, so confirm the date with yours.
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.
Migration can take several weeks from first consultation to full deployment, and longer for businesses with multiple sites, complex call routing or integrations with existing systems. With the switch-off on 31 January 2027, start now if you have not already.
Our Methodology
The calculator uses fixed assumptions you can override: VoIP at £15 per user a month plus 1p a minute, and traditional lines at £25 a month plus 5p a minute, with £150 per desk handset and £1,500 installation for a traditional system. The £15 VoIP figure sits inside the published prices we checked on 13 October 2026 (bOnline £13.95, Vonage £15, NBC £17.99, BT £18, all before VAT). The traditional line and call charges are planning assumptions, because carriers’ business rates vary by contract.
The comparison includes both the obvious costs (per-user fees, line rental, call charges) and one-off costs that are easy to miss (handsets and installation). For the most accurate result, replace the defaults with the quotes you have been given.
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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