Once you're in a meeting, you can lock the voice portion of the meeting so that only invited users are attending. After a meeting has been locked, other users will need to request entry to be allowed into the meeting.
Press #41 to lock the meeting.
Press #41 again to unlock the meeting.
Note: vMeeting Moderator displays users who have dialled into the meeting but put on hold due to the meeting's locked status, by showing icon next the user.