Short answer: yes, Microsoft Teams can replace your business phone system, but whether it should depends on how your team actually makes and takes calls. We get asked this every week, usually after a client's phone contract is up for renewal and someone in the office has spotted that Teams has a little phone icon in it.
This post is the honest version of that conversation. No vendor spin, no "it depends" cop-out, just what actually works for the small and medium businesses we look after across Birmingham and the West Midlands.
The three ways to make Teams a real phone system
Out of the box, Teams handles internal calls between your colleagues. To take external calls, actual customers ringing your published number, you need one of three setups:
- Microsoft Calling Plans, Microsoft becomes your phone provider. Simple, but expensive and limited outside the UK/US.
- Operator Connect, A third-party telco (BT, Gamma, etc.) provides the lines, but they show up natively inside Teams admin.
- Direct Routing, You bring your own SIP trunk and connect it via a Session Border Controller. Most flexible, most technical to set up.
For most SMEs we work with, Operator Connect is the sweet spot. You keep your numbers, your contracts stay sensible, and the admin is one click instead of a project.
Where Teams Phone genuinely shines
- Hybrid teams. If half your people are at home and half are in the office, Teams already knows where everyone is. Calls follow them.
- One app, one inbox. Voicemails, transcripts, chat history and call recordings all sit alongside meetings. Less context-switching.
- Microsoft 365 stack. If you're already paying for Business Standard or Premium, adding Teams Phone is a smaller licensing jump than running a separate platform. See our Microsoft 365 and cloud support page for how the licensing maps together.
Where Teams Phone falls short (and why we sometimes recommend 3CX instead)
This is the bit nobody at Microsoft will tell you.
- Call queues and IVRs are basic. If you run a busy reception, a sales team with skills-based routing, or anything resembling a small contact centre, Teams' Auto Attendant feels primitive.
- Wallboards and reporting are an extra cost. Real-time queue visibility, the screen on the wall showing who's on a call, how many are waiting, average wait time, needs a third-party add-on.
- Per-user licensing scales fast. A 30-seat business adding Teams Phone Standard plus a Calling Plan can quickly outprice a hosted PBX.
This is where 3CX comes in. We're a 3CX certified partner, and for businesses with proper call-handling needs (legal, healthcare reception, retail support lines), 3CX usually wins on features-per-pound. It also integrates with Teams, so your colleagues can still make and receive calls inside the Teams app while the PBX heavy lifting happens in 3CX behind the scenes.
The honest decision tree
Use Teams Phone if:
- You've got fewer than ~25 users making mostly outbound or 1-to-1 calls
- You're already on Microsoft 365 Business Premium
- You don't need wallboards, complex queues or skills-based routing
- Your team is genuinely hybrid and lives inside Teams already
Use 3CX (or a hosted PBX) if:
- You handle inbound call volume that needs queues, callbacks or overflow rules
- You want predictable per-system pricing instead of per-user
- You need call recording for compliance (legal, financial, healthcare)
- You want CRM integration (HubSpot, Salesforce, Microsoft Dynamics) without paying per integration
What we'd actually do for a 20-person SME today
Honestly? Teams Phone via Operator Connect, unless there's a clear reception or contact-centre requirement. The simplicity and the single-pane-of-glass usually outweigh the feature gap. When the requirement is real call handling, 3CX integrated with Teams gives you the best of both worlds, Teams as the user experience, 3CX as the engine.
Common questions
Will I lose my existing phone numbers? No. Both Teams (via Operator Connect) and 3CX support number porting. We handle the porting paperwork as part of any migration we run.
What about call quality? Both run on standard SIP/WebRTC. Quality depends on your internet, not the platform. We always test connection quality before recommending a cutover, see our process on the communications and VoIP page.
Can I have desk phones? Yes, both platforms support certified Yealink, Polycom and Snom handsets. Useful for reception and managers who don't want to wear a headset all day.
How long does a migration take? For a typical 20-50 user business, 4-6 weeks end-to-end including number porting (the porting itself is usually the bottleneck, not the technology).
Want a straight answer for your business?
Send us your current phone bill and a rough headcount and we'll tell you, in writing, which option will work out cheaper and better, Teams, 3CX or staying put. No sales pitch, no obligation.
Book a 15-minute call or have a look at our communications service page for the full breakdown.