Currently the recommended maximum number of attendees is 100 call connections.
This includes users who are joined to the call on the app with audio, or on the phone. Users who are connected to the call without audio don't count as a call connection.
If more than 100 people try to join the call, they will get a recorded message letting them know that the meeting is full.
If the meeting organizer tries to schedule a meeting with more than 100 attendees, they will receive an email letting them know they've exceeded the maximum number of attendees, and the call will not be scheduled.