Yealink T46G Skype For Business Edition User Manual page 169

To disable conference announcements:
During a conference call, press More->U.Anc to disable announcement.
1.
To enable conference announcements:
During a conference call, press More->E.Anc to enable announcement.
1.
Locking or Unlocking the Conference
Only the organizer and presenters can lock or unlock the conference.
The organizer and presenters can lock a conference call to prevent other people from joining
the conference call without an organizer's or presenter's approval.
To lock a conference:
During an active conference, press More->ConfLock to lock the conference.
1.
Basic Call Features
157