We have been running with Teams direct routing for a few months now and are still having some ongoing issues. Right now we are having issues adding additional users to use the direct route. I’m just collecting some documentation and links about the details of direct routing to gather here.
It’s just a dump of links
https://docs.microsoft.com/en-us/MicrosoftTeams/direct-routing-configure
https://docs.microsoft.com/en-us/MicrosoftTeams/direct-routing-plan
https://www.myskypelab.com/2019/02/microsoft-teams-direct-routing-tool.html