Enable DND Emergency on Yealink T46S
Navigate tot he phones IP address and enter your login details factory default is admin/admin
Navigate to the "Features" tab, then "DND Emergency" and set the drop down menu to "enabled"
Enter either a singular value
or a series of values (comma separated)
You may now barge through a phones DND setting via intercom. In Meridian Cloud the function is activated via an approved phone by 08+Overridden-Extension-Number from one of the extensions you've approved via the above process.