The following is a summary of how MS Teams uses components for direct routing of normal calls.

• Teams User > Dial plan > Voice routing policy > PSTN usage > Voice routes > SBCs

1. The MS Teams user dials a number:

2. Dial plan

   MS Teams checks the number for a match in the user's associated dial plan. If a match occurs, the dial plan applies the number translation, otherwise MS Teams drops the call. The translation can include allowing the number dialed to remain as is.

3. Voice routing policy

   The user's associated voice routing policy indicates the PSTN usage records they can use.

4. PSTN usage

   MS Teams uses PSTN usage records to link a user's voice routing policy and the voice routes that the user's calls can use. The same PSTN usage must appear in each.

5. Voice routes

   MS Teams checks the translated number for a match in the available voice routes. MS Teams only checks voice routes with a PSTN usage that match a usage in the user's voice routing policy.

6. SBC

   The matched voice route specifies the SBC or SBCs to use. MS Teams uses the SBC if it is available. Otherwise, MS Teams attempts to match another route with the same usage.

Routing Failure

In the above call flow, if direct routing fails at any point, MS Teams redirects the call to Microsoft Calling Plans if configured for the user. Otherwise, MS Teams drops the call.