3CX Phone System: Capabilities, Licensing & Why It Works for SMEs

3CX is an open-platform IP PBX used by over 600,000 businesses worldwide. Unlike closed providers (8x8, RingCentral, Teams Phone) it's a software PBX you can self-host, run in the cloud of your choice, or have us host for you, with a licence cost that doesn't scale per user. For a lot of UK SMEs, that pricing shape alone is why it keeps winning deals.

This guide walks through what 3CX actually does, what's included at each licence tier, and where it makes sense.

What 3CX is

A unified communications platform that covers:

• Voice, hosted or on-prem IP PBX, full PBX feature set
• Video conferencing, browser-based, no plugins, up to 250 participants
• Live chat, embedded on your website, routes into the same agent queue as phone calls
• WhatsApp & Facebook Messenger integration, business messaging handled inside the same agent workspace
• Mobile & desktop apps, iOS, Android, Windows, Mac, plus a web client
• SIP trunk agnostic, bring your own SIP provider, avoiding vendor lock-in

It's not a hosted service like RingCentral where you're paying per user per month for everything, it's a platform you licence once, based on how many simultaneous calls you need, not total users.

Core capabilities worth knowing about

Call handling

Everything a traditional PBX does, plus the things they charged extra for:

• Auto-attendant / IVR (digital receptionist)
• Ring groups, hunt groups, queues with skill-based routing
• Call recording (with consent announcement built in)
• Voicemail to email with transcription
• Time-based routing (office hours vs out-of-hours)
• Call parking, transfer, conference

Agent features (Pro and above)

For teams that take a lot of inbound:

• Real-time queue dashboards
• Wallboards showing SLAs, abandoned calls, longest wait
• Agent status and availability controls
• Call listening, whisper, barge for coaching
• CRM integration, auto-popup on inbound calls for Microsoft 365, HubSpot, Zoho, Salesforce, Pipedrive, Freshdesk, and many more

Mobile working

The 3CX iOS/Android apps turn any smartphone into an office extension with:

• Your desk extension number for outbound calls (caller ID matches the business)
• Push notifications for inbound calls even when the app is in background
• Presence and chat with internal colleagues
• Full queue / ring-group participation as if you were sat at your desk

This is the feature that kills mobile-bill top-ups for teams that work hybrid.

Video meetings

Built-in, browser-based. No Zoom licence. No Teams licence. Guests click a link, their browser opens, they're in. Includes screen share, polls, chat, breakout rooms, and recording. Good enough for 80% of meetings; not quite Teams polish for the other 20%.

Licensing explained

3CX sells licences based on simultaneous calls (SCs), not users. A 4SC licence means four concurrent calls. A business with 30 staff typically needs a 4SC or 8SC licence because most staff aren't on the phone simultaneously.

Four editions (as of late 2025):

Free

• Up to 10 users
• Web client, mobile apps, video conferencing
• One SIP trunk
• Good for microbusinesses (1–5 staff) to try it out
• No call queues, no CRM integration, no call recording, no reporting

Startup Pro (formerly Small Business)

• Up to 10 users / 4 simultaneous calls
• Call queues, CRM integration, call recording, basic reporting
• Hosted by 3CX (SaaS), cheapest tier for managed hosting
• Typical for firms under 10 staff that need proper PBX features

Enterprise / Pro (self-hosted or partner-hosted)

• Per-SC pricing (4, 8, 16, 24, 32, 48, 64, 128, 192, 256)
• All Pro features plus skill-based routing, advanced reporting, multi-site, hot desking
• You (or a partner like us) host it, on-prem, in Azure/AWS, or on a UK data-centre VPS
• Typical sweet spot for 15–200 staff

Enterprise+

• All Enterprise features
• MS Teams integration (direct routing), standby instance (failover), custom IP phone firmware, call flow designer

Rough cost comparison: a 30-user office needing 8SC, self-hosted 3CX Pro is roughly £600–£900/year in 3CX licence fees plus whatever you pay for SIP minutes. The same team on Teams Phone would be £6/user/month = £2,160/year just for the phone add-on, before SIP. Hosted providers like RingCentral sit around £20–£30/user/month = £7,200–£10,800/year.

This is why 3CX wins when procurement gets involved.

Where 3CX shines

• Businesses with fluctuating headcount, the SC-based licence doesn't punish you for hiring seasonal or temp staff
• Firms that need call recording everywhere, included rather than an expensive add-on
• Hybrid teams needing mobile-as-extension, 3CX mobile apps are genuinely good
• Client-facing teams, the live chat / WhatsApp / Messenger unification into one agent queue is unique at this price point
• Anyone who wants vendor-independent SIP, you can switch SIP providers without changing your phone system

Where 3CX is not the right fit

• Tiny teams (1–4 staff) who just want the simplest thing, the free tier works but hosted options from simpler providers may be less admin
• Microsoft-everything shops who need deep Teams calling integration for external calls, Teams Phone with Direct Routing is a more seamless fit (though you can run 3CX alongside Teams for internal)
• Heavy contact-centre operations, over ~30 concurrent agents with complex workflows, you're better off on a dedicated CCaaS platform

How we deploy it

For most clients we host 3CX on a dedicated UK-region Azure or UK data-centre VPS, gives you the per-SC pricing advantage plus full backup, monitoring, and patching as part of our Managed IT service. We pair it with a UK-based SIP provider (Gamma, Voiceflex, TelcoSwitch) on inclusive-minute bundles that typically work out at £3–£6 per user per month for unlimited UK landline and mobile minutes.

What you get end-to-end:

• Hosted 3CX PBX (configured, hardened, patched monthly)
• UK SIP trunks with inclusive minutes
• Yealink or Fanvil desk phones (if needed) or just softphone/mobile only
• Number porting from your existing provider
• Call flow design and IVR setup
• Staff training and handover

Switchover is typically two to three weeks end-to-end, with zero downtime on cutover day thanks to parallel running.

If you want a quote or a demo of the platform, drop us a line.