3CX Licensing Explained: Simultaneous Calls, Not Extensions
3CX is licensed by simultaneous calls, not per user — which can save you a lot. Here's how the Small/Medium/Large tiers work and how to size them.
If you've ever looked at a 3CX quote and tried to work out what you're actually paying for, you're not alone. The most common mistake people make is assuming 3CX charges you per person, or per phone, on their desk. It doesn't. 3CX is licensed by the number of simultaneous calls your business can make and receive at once, not by the number of extensions you set up. Get that one idea straight and the pricing suddenly makes a lot more sense, and you usually end up buying a smaller licence than you feared.
Extensions are free. Concurrent calls are what you license.
An extension is just a user, a handset, a softphone on a laptop, or an app on a mobile. With 3CX you can create as many extensions as you like. A 20-person office, a 50-person office, it doesn't change the licence. What you pay for is how many of those people can be on a call at the same moment.
That distinction matters because, in most businesses, only a fraction of your team is on the phone simultaneously. Think about your own office: even on a busy morning, you might have 18 staff but rarely more than 6 or 7 live calls at once. So you'd license for the calls, not the heads, and the rest of the time those calls are shared across everyone.
3CX licences come in tiers based on simultaneous calls. The common sizes are:
Small
4 simultaneous calls
Medium
8 simultaneous calls
Large
16 simultaneous calls
A rough rule of thumb is that simultaneous calls tend to land somewhere around a third of your total users, but it varies a lot by industry. A quiet professional services firm sits well below that; a busy sales floor or a support desk sits above it. The honest answer is that it depends on your call patterns, which is exactly the kind of thing worth checking before you commit.
What's bundled in (and worth knowing about)
One of the reasons 3CX tends to work out cheaper than older phone systems is that a lot of the features people expect to pay extra for are simply included. With a 3CX system you get:
Free calls between offices and branches
internal and inter-site calls don't touch your call limit or your bill.
Free video meetings
for up to 250 participants, built in.
Free live chat
you can drop onto your website, with messages landing in the same system as your calls.
Apps for desktop and mobile
, so a "desk extension" can ring on someone's phone wherever they are.
You can run 3CX hosted in the cloud or on-premise on your own hardware, whichever suits your setup and your appetite for managing servers. Most smaller businesses go hosted to keep things simple. You can read more on our 3CX phone system page, or compare it against the other options on our business phone systems overview.
What the licence does not include: the calls themselves
Here's the part that trips people up. Your 3CX licence is the software that runs the phone system. It doesn't include the actual phone line that connects you to the outside world. For that you need SIP trunks — the modern replacement for old ISDN and PSTN lines — which carry your calls and your phone numbers over the internet.
So a complete 3CX setup is two parts: the 3CX licence (sized by simultaneous calls) plus SIP trunks to carry those calls. The good news is the two are sized the same way, by concurrent calls, so they line up neatly. If you'd rather not run a phone system at all, a hosted PBX or a fully managed business VoIP service covers the same ground with less to think about.
Is 3CX always the right choice? No.
We'll be straight with you: 3CX is excellent value for a lot of businesses, but it isn't the only sensible answer. If your team already lives in Microsoft Teams, it can often make more sense to add calling directly to Teams using Direct Routing rather than running a separate system. We set this up without you needing your own SBC hardware. We're vendor-neutral, so we'll point you at whatever genuinely fits, not whatever we'd prefer to sell.
If you're moving off ageing equipment and want to know what you'd actually save, our free bill analysis is a no-obligation read of your current spend.
Frequently asked questions
Do I need a 3CX licence for every staff member?
No. You can add as many extensions as you have people, at no extra licence cost. You only license for the number of calls happening at the same time, which is almost always far fewer than your headcount.
How do I know which tier I need — 4, 8 or 16 calls?
It comes down to your busiest moment, not your average. A quick look at your current call records (or your last few phone bills) usually shows the peak. If you're unsure, we'll work it out with you so you don't over-buy or get caught short.
Can I start small and grow later?
Yes. Licences can be upgraded as your business grows, so it's fine to start at the tier that matches today's call volume and move up when you genuinely need more. There's no need to pay for capacity you're not using yet.
Talk it through with real local humans
We're SIP Connect, based at Greensborough Plaza in Greensborough and looking after businesses across north-east Melbourne and Australia. No offshore call centre, no scripts, just local people with over 80 years of combined experience who'll size a 3CX system honestly. Most installs are done in days, not weeks, and our bill reviews have identified savings of up to 65%.
If you'd like a plain-English chat about whether 3CX is right for you, or whether Teams or a hosted PBX would suit you better, get in touch or call 1300 747 266. Real Connections. Real Easy.
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