The number of callers that can register to speak at a meeting can be limited within the More Registration Options drop-down of a meeting. The number of pre-registered speakers can be limited to a specific number and the time window for pre-registering can be limited to avoid registration too close to the beginning of a meeting.
Please note that these settings do not impact the number of speakers that can call into a meeting, but only the number of speakers who can pre-register to speak.
Navigate to the Meetings & Offline tab:
Create a new meeting, or edit an existing meeting.
Scroll down and open the More Registration Options menu within the Meeting editor:
Click Event Registration on to enable registration. The settings below will only apply if this is enabled!
Toggle Enable speaker pre-registration to allow users to register to speak.
Enter a number here to limit the number of speakers who can pre-register. By setting this to 0, there will be no enforced limit.
The number here will be the number of minutes before the meeting start time that serves as the cutoff for allowed pre-registration.