Direct Routing is the connection Microsoft built for plugging an outside phone system into Teams, so a real phone number can ring straight into the Teams app your team already has open. Teams stays the thing people use every day. What changes is what is running behind the number.
What the call does
In one sentence: it is the trunk Microsoft built for connecting a phone system to Teams, so a call can arrive on a real number and ring inside the Teams app rather than through a separate calling tool. It is the connector we are building next, tenant by tenant, rather than a switch every account already has today.
Nobody has to learn a second tool to answer the phone. Teams keeps the chat, the meetings and the presence people already know, and a call lands in the same place a message would. What sits behind the number is the rest of the platform: routing, groups and a record of the call, managed the same way as every other line.
Direct Routing is a Microsoft feature, so the licence sits with Microsoft rather than with us. Each person taking calls this way needs a Microsoft Teams licence plus the Teams Phone add-on, which is Microsoft's current name for what it used to sell as Phone System, assigned in the Microsoft 365 admin center the same way any other licence is.
A number does not have to pick between Teams and a handset. Point it at a desk phone or the browser phone at the same time as Teams, and whichever one is picked up first is the one that answers, the same simultaneous-ring rule every other line on the platform already follows.
Most people never open the second column. It is one click away rather than spread across the first.
On every plan
This is included whichever plan you are on, with no add-on and no module to enable. Plans differ by how calls are distributed and how long the history is kept.