How Many VoIP Lines Does My Business Need?
Most business owners ask this question when they're switching to VoIP, and they frame it the wrong way: "I have 15 staff, so do I need 15 lines?" The answer is almost certainly no — and understanding why will save you money every month.
With hosted VoIP, you're not buying traditional lines. You're buying user licences. And the number of licences you need depends on one thing: how many people could be on a call at the same time, not how many people work for you.
Quick answers:
- A 10-person team typically needs 4–6 user licences
- A 20-person office rarely needs more than 10–12
- Reception desks, sales teams, and support staff drive your number — admin and back-office staff rarely do
- You can add or remove users any time, so there's no need to over-buy upfront
Lines vs Users — The Key Difference with VoIP
Under the old ISDN system, you paid for physical channels. Each channel handled one call. Whether someone was using it or not, you paid for it. Businesses routinely over-provisioned just to avoid engaged tones.
VoIP works differently. There are no physical lines. When someone makes or receives a call, it uses your internet connection. Each user licence gives one person the ability to make and receive calls — on their desk phone, laptop, or mobile app. Two people can be on calls at the same time with two licences.
What this means in practice: you only pay for the users you actually have. Add someone in March, pay for them from March. Remove a user in June, stop paying from June. Your dashboard handles it with no engineer or contract renegotiation required.
How to Estimate the Right Number of User Licences
The starting point is your busy period. Think about your busiest time of day. At that moment, how many people are actually on a call?
For most UK SMEs, the answer is somewhere between 30% and 40% of staff. Not everyone is on the phone. The warehouse manager is in the warehouse. The accounts person is in a spreadsheet. The MD is in a meeting. The people driving your call volume are customer-facing and sales roles.
Here's a practical way to work it out:
- List the roles that use the phone regularly — reception, sales, account management, support, operations
- Estimate peak simultaneous calls for each group — not total staff in that team, but how many could realistically be on a call at once
- Add a spare licence or two — for growth, or to cover a busy day without anyone getting an engaged tone
Walk through a real example. A 15-person business:
| Role | Staff | Licences needed |
|---|---|---|
| Reception | 1 | 1 |
| Sales team | 4 | 3 |
| Operations | 3 | 2 |
| Management | 2 | 1–2 |
| Accounts/admin | 5 | 0–1 |
| Total | 15 | 7–9 |
That business doesn't need 15 licences. It needs 7–9. That's a significant saving — and it's still enough to handle peak call volume without anyone hitting a busy signal.
Common Scenarios
Retail and Trade Businesses. Most of your staff aren't on the phone. The person fitting a kitchen isn't taking calls. Your driver isn't either. You probably need one licence for whoever handles inbound enquiries, one for the person who manages bookings, and maybe one or two more for management. A 12-person trade business often needs just 3–5 licences.
Professional Services (Accountants, Solicitors, Consultants). Here the phone use is heavier. Clients call their specific contact, so you may want a licence per fee-earner — not because they're all on calls simultaneously, but because direct dial numbers matter for client relationships. A 10-person practice might genuinely need 8–10 licences. The Samurai plan at £14.99 per user gives you unlimited UK minutes and a direct number per user at a sensible cost.
Call-Heavy Businesses (Sales Teams, Customer Support). If agents spend most of their day on calls, you're closer to one licence per person. The overlap is high, and you don't want anyone waiting. For these businesses, the Shogun plan at £24.99 per user makes sense — unlimited calls, no anxiety about usage, and the features to support a busy team.
What VoIPninjas Recommends
Start lean. It's genuinely easier to add a licence than to explain to your boss why you've been overpaying for a year.
Our recommendation for most small businesses switching from ISDN or a traditional phone system:
- Start with one licence per person who regularly makes or receives calls
- Don't include pure back-office staff unless they occasionally deal with suppliers or customers by phone
- Add a buffer of one or two licences if you expect to hire in the next six months
- Review after 90 days — you'll quickly see from your dashboard who's actually using their licence
On the plan side: if your team makes a lot of UK calls, go straight to Shogun. The unlimited minutes remove any temptation to underprovision to keep bills down. If call volumes are modest, Samurai gives you everything most SMEs need at a sensible price.
All plans run on 28-day rolling contracts. There's no penalty for adjusting as you go.
Not sure where to start? Call us on 0330 043 2388 and we'll work out the right number of licences for your team in about five minutes. Or start your free 14-day trial — no card required, live within 10 working days. Get a Free Quote → No tie-in, no setup fees. Most businesses are fully live within 10 working days.
Frequently Asked Questions
Does every member of staff need their own VoIP licence?
No. You only need a licence for people who actively use the phone as part of their job. Back-office staff, warehouse operatives, and others who rarely make or take calls don't need a licence — and you won't be paying for one they don't use.
What happens if two people try to use the same VoIP licence at once?
Each user licence is tied to one user. If that user is already on a call, a second incoming call can go to voicemail or be diverted, depending on how you've set it up. This is why you need enough licences to cover your peak simultaneous call volume.
Can I add more VoIP licences mid-month?
Yes. With VoIPninjas, you add a user from your dashboard and billing is pro-rated. If you hire someone in the middle of the month, you only pay for the days they're active. No waiting around, no contract amendment required.
How many VoIP lines does a 10-person business typically need?
Most 10-person businesses need between 4 and 7 user licences. It depends on the mix of roles. A team of 10 where half are customer-facing will need more than a team of 10 where most people are in technical or admin work. Use the 30–40% concurrent call estimate as your starting point, then adjust for your specific roles.