@Cameron McBroom , Following-up on this, Teams meeting (onlineMeeting) allows server to receive notifications about the meeting.
Please check this doc: Get change notifications for Microsoft Teams meeting call updates - Microsoft Graph | Microsoft Learn
-- Neither ACS nor Graph provides server events for Teams 1:1 or Teams group calls. Client events can be only received when the user is part of the roster (i.e. Join the call/meeting.)
Kindly let us know how it goes. I'll convert comment to answer.
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