14.11.4. MS Teams Direct Routing Configuration 
This document describes how to connect the Unify OpenScape SBC (with OpenScape 4000)
to Microsoft Teams Direct Routing configuration. Microsoft Teams Direct Routing
configuration is not included in current document and may be found under https://docs.microsoft.com/en-us/microsoftteams/direct-routing-configure.
INFO:
Make sure the SBC is added with Forward P-Asserted-Identity (PAI) header
set to Off.
Using the Microsoft Teams admin center, in the left navigation panel, go to Voice
> Direct Routing, then click the SBCs tab.
Select the already configured SBC (based on Microsoft official documentation provided
above) and click the Edit button. Next, set the Forward
P-Asserted-Identity (PAI) header to off and click the Save button.
INFO:
You need to open ports in your firewall for the IP address ranges to allow
incoming and outgoing traffic to and from the addresses for signaling purposes.
For more information, refer to the Microsoft documentation:
https://learn.microsoft.com/en-us/microsoftteams/direct-routing-plan