Can Microsoft Teams replace your PBX?

What Teams Phone can do

Teams Phone is the telephony in Microsoft 365. Among other things, it includes:

• Auto attendant: a voice menu that directs callers to the right place.
• Call queues: calls to a number are distributed among a group of staff, with rules for what happens when nobody can answer.
• Voicemail, call forwarding and simultaneous ringing.
• Call groups and delegation: colleagues can answer each other’s calls, and an assistant can make and answer calls for a manager.
• Call park: a call is parked and picked up by someone else.

If you mainly have office users calling from their own number, plus a few simple queues and menus, that is often enough. Microsoft itself says that the calling features in Teams meet the needs of some organisations, and that a contact centre can be connected to Teams Phone when needs are greater.

What often needs a separate solution

• Contact centre: Teams call queues handle calls. If phone, email and chat need to share one flow, with reports and quality monitoring, they rarely go far enough. The answer is a contact centre connected to Teams, such as Mitel CX. Microsoft has programmes for certifying such solutions.
• Attendant console: switchboard operators need to see presence and absence information and transfer calls quickly, often from several systems. That takes an attendant console that can read presence from Teams, such as Trio Enterprise.
• Alarms, lifts, door phones and fax: analogue devices cannot be connected directly to Teams. They stay on the PBX or connect through an SBC or analogue adapter.
• DECT and other wireless phones on site: not all models work with Teams. Several DECT systems can connect through Microsoft’s SIP Gateway, but each model needs checking.
• Telephony that must not stop: Teams runs in the cloud and needs a connection to Microsoft. The answer is survivable mode in an on-site SBC, with some limitations, and backup routes to the operator.

Emergency calls also need planning. With Direct Routing, the route and policy for the emergency number must be set up and tested, and the address must be registered with the operator for every number.

Teams also needs a way out to the phone network

The Teams Phone licence gives you the phone features, but not the connection to the phone network. You choose that separately, in one of four ways:

• Calling Plan: Microsoft is the operator.
• Operator Connect: an operator in Microsoft’s programme handles the connection.
• Teams Phone Mobile: the mobile number becomes the number in Teams. It cannot be used for call queues and auto attendants.
• Direct Routing: any operator, through a certified SBC (Session Border Controller).

If Teams is to connect to an existing PBX or to analogue devices, that part needs Direct Routing and an SBC. The options can be combined. Read more in the guide Direct Routing or Operator Connect?

Look beyond the licence

Comparing the price of a Teams Phone licence with the cost of the PBX does not tell you much. Count the whole solution:

• Teams Phone for every user with their own number. The licence is included in some Microsoft 365 plans and is otherwise available as an add-on.
• Licences for shared phones.
• Calls and numbers with the operator, or a Calling Plan from Microsoft.
• The SBC and running it, if you choose Direct Routing. For example, its certificates must be renewed more and more often.
• The contact centre, attendant console and anything else that needs a separate solution.
• The PBX while you move.

Two systems cost money in licences, support and skills, so plan an end date if the PBX is to go.

How to find out what applies to you

Start with what your PBX actually does today, not what it can do. Go through:

• Who calls the most, and from which devices.
• Which queues, voice menus and attendant consoles you have, and who answers.
• What else depends on the PBX: alarms, lifts, door phones, DECT, fax, recording and integrations.
• Which numbers and operator contracts you have, and when they expire.
• What must keep working when the internet or Microsoft is down.
• How long the manufacturer will support your PBX. Read more about the PBX lifecycle.

Give each such function an owner and a decision: move, replace or keep.

You do not have to decide everything at once

With Direct Routing, Teams and your PBX can work side by side while you move one group at a time. Mitel supports this from MiVoice Business, MiVoice 5000, MX-ONE and OpenScape. Read more in the guide Teams and your existing PBX.

If your PBX works well and has manufacturer support, you do not need to replace it to get Teams. How to weigh that up is covered in the guide Upgrade or replace your PBX?

We work with both PBXs and Teams Phone. If you want to work out what should move and what should stay, you can book a consultation.

Last updated 31 October 2026.