How Does Direct Routing Choose Which SBC Gets a Call?
Your SBCs get added to a gateway list in Office 365. You can assign them a priority if you wish. When a priority is set, calls from Teams will attempt to be routed to the SBC with the highest priority if it is available.
If no priority is set, or the preferred SBC is unavailable, calls will be routed to the SBC in the list that last provided SIP OPTIONS to Microsoft.
Mark is an Independent Microsoft Teams Consultant with over 15 years experience in Microsoft Technology. Mark is the founder of Commsverse, a dedicated Microsoft Teams conference and former MVP. You can follow him on twitter @UnifiedVale