Stop People Joining a Teams Meeting
Message center notification MC251564 published on April 20 says that meeting organizers can lock meetings to prevent participants. This feature is supported in the Teams desktop client only and will roll out at the end of-May. The feature is described in Microsoft roadmap item 80669. Locking a meeting stops anyone, including invitees, from joining the meeting using any Teams client or via audio conferencing. The option to lock a meeting is in the Participants menu (Figure 1).

Figure 2 shows the warning the organizer sees before Teams locks a meeting.

When a meeting is locked, Teams blocks anyone who attempts to join the meeting (Figure 3). The lock remains in force until the organizer unlocks or leaves the meeting.

Meeting Invitees Can Access Meeting Resources
Even though they might be blocked from joining, people invited to the meeting can still access the meeting chat when the meeting is in progress and other resources like the transcript and recording after the meeting finishes.
Blocking joining while allowing attendees to have continued access to meeting resources means that the organizer can advise people that the meeting is locked by posting to the meeting chat. For instance, the organizer could say why they have locked the meeting (perhaps because a participant wishes to share some very confidential information) and when they expect to reopen the call.
Meeting Locks Increase Organizer Control
Microsoft has invested in creating a bunch of features to help organizers control access to meetings over the last few months. Granular control over lobby bypass allows organizers to monitor who joins a meeting, while meeting settings also dictate what attendees can do during a meeting. While some might think this overkill, it reflects the need to guarantee the confidentiality and security of some meetings hosted in Teams, such as important board discussions, negotiations between companies, sensitive HR interactions with people, and so on. Meeting organizers can control:
- Who is invited to meetings and if attendees can forward invitations to other people.
- Who can join a meeting automatically and who must wait in the lobby for admittance.
- Who presents during a meeting.
- The muting of meeting attendees and if they can use their camera to create a video feed.
- Blocking further attendee joins during a meeting.
Most Teams meetings won’t need to use any or all these settings, but that’s not the point. What’s more important is that the settings exist and are available when necessary. You’ll be glad of the control when the need arises.
So a guest who left the meeting, will not be allowed to rejoin once the meeting is locked?
No one can rejoin until the meeting is unlocked.
Yupp pretty much….
I locked the meeting and now do not have the unlock meeting option and has caused a huge disruption in our meeting. Help!