A typical 10-person UK business on BT Business spends around £1,680–£2,160 a year just on line rental — before a single call is made. Switch to VoIP and that bill drops by 40–60% on average. Here’s exactly how the maths works.
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The short answer
- Monthly savings: Most SMEs cut their phone bill from £14–18 per user down to £5.99–£14.99 per user
- First-year saving (10 users): Typically £720–£1,080 compared with BT Business
- Hidden savings: No PBX hardware, no engineer call-outs, no per-handset licence fees
- Locked-in costs avoided: VoIP runs on 28-day rolling contracts — no 24-month tie-ins
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What UK businesses actually spend on traditional phone systems
BT Business line rental currently runs at £14–18 per user per month, depending on your package and how long you’ve been a customer. That’s the base cost before you add call charges.
On top of that, most businesses on a traditional system have paid for hardware at some point — a PBX box, physical handsets, installation by an engineer. That initial outlay typically runs to £500–£2,000 for a 10-person office, and it sits on your desk depreciating while the world moves on.
Then there are the contract terms. BT Business standard contracts run to 24 months. If your headcount changes, your costs don’t flex — you’re paying for lines you no longer need, or scrambling to add capacity with another set of fees.
Check out our full BT Business vs VoIPninjas cost comparison for a line-by-line breakdown.
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What VoIP costs instead — real numbers
VoIPninjas offers three plans, priced per user per month:
| Plan | Price/user/month | Best for |
| **Ronin** | £5.99 | Light users, second lines, part-time staff |
| **Samurai** | £14.99 | Most businesses — unlimited UK calls included |
| **Shogun** | £24.99 | Teams calling internationally across 55+ countries |
No setup fees. No hardware costs. No 24-month contracts — everything runs on a 28-day rolling agreement.
10-user cost comparison: BT Business vs VoIPninjas Samurai
| Monthly cost (10 users) | £140–£180 | £149.90 |
| Annual cost | £1,680–£2,160 | £1,798.80 |
| Contract length | 24 months | 28-day rolling |
| Setup / installation | £200–£500 | £0 |
| Hardware required | Yes | No |
| **Year 1 total (inc. setup)** | **£1,880–£2,660** | **£1,798.80** |
| **Year 1 saving** | — | **£81–£861** |
By year two, when BT’s setup costs no longer appear, the Samurai plan saves you £720–£1,080 annually. If you drop to the Ronin plan for lighter users, that saving increases to well over £1,000 a year.
See our full guide to business phone system costs in 2026 if you want to model different team sizes.
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The hidden cost savings beyond the monthly bill
The line rental comparison above is just the start. There are several costs that don’t show up on a phone bill but quietly drain money every year.
No PBX hardware. A traditional phone system needs a physical box — a Private Branch Exchange — installed on-site. It needs maintenance, and eventually it needs replacing. With VoIP, the “exchange” lives in the cloud. You have nothing to install and nothing to fix.
Free internal calls. Calls between your team — across the office or between sites — cost nothing on VoIP. If you have staff working from home or across multiple locations, those savings compound fast.
Inclusive UK minutes. The Samurai and Shogun plans include unlimited calls to UK landlines and mobiles. No per-minute charges, no bill surprises at the end of the month.
Voicemail to email. Every missed call gets transcribed and dropped into your inbox. No more calling in for messages, no more lost voicemails. For a busy owner who’s often on the road, that’s a genuine time saving every week.
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International call savings — Shogun plan
If your business calls overseas regularly, the numbers get more compelling still. BT Business charges per-minute rates for international calls that add up quickly, especially to the US, Europe, or Australia.
The Shogun plan at £24.99/user/month includes calls to 55 countries — covering the US, Australia, most of Europe, and key markets in Asia and the Middle East. For a team making regular international calls, the Shogun plan often pays for itself against BT’s per-minute charges within the first two or three months.
Even compared with a basic BT package plus international bolt-ons, Shogun typically saves £8–£15 per user per month for moderate international callers.
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The PSTN switch-off makes this saving unavoidable anyway
BT is switching off the UK’s Public Switched Telephone Network (PSTN) in 2027. Every business still on a traditional landline will be forced to move — there is no alternative.
The difference is whether you move on your own terms and bank the savings now, or wait until you’re migrated under pressure with less time to choose your provider carefully.
Businesses that switch in 2026 rather than waiting for the deadline get an extra year of lower bills before the migration becomes compulsory. On a 10-person team, that’s £720–£1,000 you keep rather than hand to BT.
Read our full guide to the PSTN switch-off and what it means for your business.
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How to calculate your actual saving
The calculation is straightforward. You need three numbers:
1. Your current monthly phone bill (line rental plus average call charges)
2. The number of users on your system
3. The VoIPninjas plan that matches your usage
Then apply this formula:
> (Current monthly spend × 12) − VoIPninjas annual cost = first-year saving
Example — 10-user business on BT Business:
- Current monthly spend: £160 (line rental only, before calls)
- Annual BT cost: £1,920
- VoIPninjas Samurai (10 users): £149.90/month = £1,798.80/year
- First-year saving: £121.20 — and that’s before you factor in inclusive minutes replacing per-minute call charges, or the BT setup fee you won’t pay again
Add in the call charge savings and hardware you won’t need to replace, and a realistic first-year saving for most 10-person businesses is £600–£1,500.
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Try VoIPninjas free for 14 days
No card required. No contracts. Your number transfers across, your team is up and running the same day.
Start your free 14-day trial → Get started
If you want to talk through the numbers for your specific setup before committing, call or message us — we’ll run the calculation with you.
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Frequently asked questions
What’s the minimum saving I should expect switching from BT to VoIP?
For a business with five or more users on a standard BT Business package, a saving of £40–£60 per month is realistic on line rental alone. Add call charge savings and the total typically reaches £600–£1,000 in the first year. Smaller teams see proportionally smaller savings, but the flexibility and lack of long-term contracts deliver value beyond the headline figure.
Do I need to buy new hardware to use VoIPninjas?
No. VoIPninjas works on the devices your team already has — desktop computers, laptops, smartphones, and tablets via the app. If you prefer physical desk phones, compatible handsets are available, but they are entirely optional. Most customers run the whole system through the app and a decent headset.
Can I keep my existing business phone number?
Yes. Number porting is included as standard. Your existing geographic or non-geographic number transfers across to VoIPninjas, and your clients won’t notice any change. The process typically takes 5–10 working days, and your old number stays active throughout the transfer period.
How long does it take to set up VoIPninjas for a 10-person business?
Most businesses are fully set up within one working day. You create the account, add your users, download the app, and you’re making and receiving calls. There’s no engineer visit, no hardware to configure, and no IT knowledge required. The 14-day free trial lets you test the full system — call quality, features, and app — before you make any commitment.