How to Alert Entire Org

Hi! 

I am exploring ways to enhance mass emergency notifications. In addition to using other methods, such as mass text or phone call, the case study here would be to enhance the current capabilities and hit employees via Zoom (chat or call) during really big and bad things, like an active shooter scenario or significant internal application or infrastructure outage. Perhaps a way to post a banner to active meetings? This could even be for non-emergency messages, like HR to post messages "hey, reminder to sign up for benefits"

Is anyone familiar with a way to send a message to all within the organization, or post a zoom banner/ alert for others to see?  

Thanks!