How Microsoft Teams Direct Routing works

Direct Routing is how an organisation connects its own SBC and its own carrier to Microsoft Teams, instead of relying on Microsoft's own Calling Plans.

Bringing your own carrier to Microsoft Teams

By default, Microsoft Teams handles calling through its own Calling Plans. Direct Routing is the alternative: it lets an organisation connect its own SBC and its own ITSP to Teams instead, keeping existing carrier contracts, existing numbers, and local rates.

The SBC has to be certified, specifically

Microsoft does not accept just any SBC for Direct Routing. It only supports devices from a published list of certified vendors, tested for interoperability directly with Microsoft. Connect an uncertified SBC and it may technically work, but Microsoft will not support you if it breaks.

What actually has to be in place

A working Direct Routing deployment needs a certified SBC with a public IP address, a publicly trusted TLS certificate, a proper DNS record, and at least one telephony trunk from an ITSP feeding into it. Once configured, the SBC becomes the exact bridge described in the full call path, just with Microsoft's cloud sitting where an internal PBX would normally be.

Direct Routing versus Operator Connect

Microsoft also offers Operator Connect, a managed alternative where a certified carrier's SBC is already built into the Teams Admin Center, removing the need to run your own SBC at all. Direct Routing remains the choice when an organisation wants full control over carrier selection, custom call routing, or has an existing SBC investment it wants to keep using.