Microsoft Teams Phone vs
a traditional PBX
Teams Phone puts external calls inside Microsoft 365, while a traditional on-premise PBX keeps calling on hardware you own, with local control of routing, handsets and numbers.
The choice is not which product looks more modern. It is where your calls should live, and what you're prepared to own. Microsoft Teams Phone puts inbound and outbound calling inside Teams, on your Microsoft 365 tenancy. Staff make and take external calls from Teams, next to meetings and chat. A traditional on-premise PBX sits in your building. Handsets, routing and numbers stay on site, and the system doesn't need a Microsoft licence.
Teams Phone is usually the simpler path if you already run Microsoft 365 and people work from more than one place. The PBX still wins where analogue devices, customised call flows, or calling during an internet outage actually matter. Wanzo can configure Teams Phone, or keep a PBX running with SIP trunks and the network underneath. We start from how you handle calls today, not from a preference for cloud.
| Factor | Microsoft Teams Phone | A traditional on-premise PBX |
|---|---|---|
| Where calls live | Teams Phone handles external calls inside Microsoft Teams. Staff use a computer, a phone or a certified handset, all tied to the same Microsoft 365 user. | Calls sit on a PBX in your building, with desk handsets and local numbering. The phone system is separate from Microsoft 365 unless you connect them later. |
| Hybrid working | Anyone with Teams and a working internet connection can take the company number. That is the main reason hybrid firms move calling into Teams. | Remote staff usually need a VPN, a softphone or a second system. Traditional PBX design assumes people are at a desk on the local network. |
| Internet outages | External calling needs a working internet connection and a network that treats voice well. If the line drops, Teams Phone drops with it. | Internal calls between handsets can keep going when the internet is down. External calls still need a working PSTN or SIP path, but local calling does not wait on the WAN. |
| Analogue devices | Analogue devices such as lift phones, alarm panels and some door-entry systems do not sit natively in Teams. They need adapters or a separate arrangement. | A traditional PBX still talks to analogue extensions. That is often why a working PBX stays, even when the rest of the firm has moved to cloud tools. |
| Call control | Teams Phone covers standard business calling: voicemail, queues, auto attendants and number management. Deeper site-specific routing is possible, but it follows Microsoft's product model. | Hunt groups, night service, analogue ports and local IVR often live on the PBX. If those rules still run the day, replacing it is a project, not a licence change. |
| How you pay | Microsoft licenses Phone on top of Microsoft 365. You pay per user and for the calling plan or Direct Routing you choose. Licence prices sit with Microsoft, not Wanzo. | You pay for hardware, maintenance and often a support contract. Once bought, extra users can be cheaper than another cloud licence, until the hardware needs replacing. |
When Microsoft Teams Phone is the right call
- You already run Microsoft 365, and staff already work in Teams for meetings and chat.
- People work from more than one site, and they need the company number on a laptop or mobile.
- You don't want to keep buying, housing and maintaining PBX hardware as staff numbers change.
When A traditional on-premise PBX is the right call
- Lift phones, alarm panels or door-entry systems still need analogue extensions the PBX already serves.
- Internal calling must keep working when the internet is down, not only when the WAN is healthy.
- Your hunt groups, night service and local IVR are complex enough that replacing them would disrupt the working day.
What we’d recommend
If the firm already runs Microsoft 365, people work from more than one place, and there are no analogue devices holding the old system in place, we'd put calling into Teams Phone. If the building still needs analogue extensions, or internal calls must survive an internet outage, we'd keep the PBX and connect it with SIP trunks. Some sites end up with both for a period: Teams for staff, the PBX for the kit that cannot move. Wanzo can deliver either. We would also look at the leased line, SD-WAN and network underneath, because call quality follows the connection. The monthly relationship covers that infrastructure when it is in scope.
Questions people ask
Can Microsoft Teams Phone replace a PBX?
Yes, for many firms. If staff already work in Microsoft 365, take calls from more than one place, and nothing analogue is tied to the old system, Teams Phone can take over inbound and outbound calling. It will not keep desk-to-desk calling alive during an internet outage, and it will not inherit years of local hunt groups without rebuilding them. Wanzo can move you to Teams Phone, or leave the PBX in place with SIP trunks. We would check analogue extensions and call-flow complexity first.
Does Teams Phone work if the internet goes down?
No. Teams Phone needs a working internet connection. If the line fails, external calling in Teams fails with it. A traditional on-premise PBX can still carry internal calls between handsets during an outage, provided the PBX has power. External PBX calls still need a PSTN circuit or SIP trunk. Wanzo would not put a firm on Teams Phone without looking at the leased line, failover and local network. Connectivity we provide comes with a 99.9% uptime SLA and 24/7 monitoring.
Can I keep my existing PBX and use Teams?
Yes. You can run both. Some firms put staff calling into Teams Phone and leave the PBX for analogue devices or a hunt group that would be painful to rebuild. SIP trunks can keep an existing PBX on the public network while you move users in stages. Wanzo can configure Teams Phone, keep a PBX on SIP trunks, and manage the network both depend on. We wouldn't remove a working PBX only because Teams is available. Monthly plans can cover the communications work plus the IT and connectivity underneath.
How much does Teams Phone cost compared with a PBX?
Teams Phone is a Microsoft licence on top of Microsoft 365, plus a calling plan or Direct Routing. Microsoft sets the prices and they change with licence mix, so we will not quote a figure. A PBX is capital hardware plus maintenance and support. Extra extensions on a PBX you already own can cost less per user than another cloud licence, until that hardware needs replacing. Wanzo manages either as part of a monthly relationship. We'll set out both options once we know your users, analogue devices and call flows.
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