Every phone system since the 90's had a feature to send a global or mass voicmail message to all phones or a group of user's . I would like to add this feature, since many have physical phones and text messaging isn't an option.
It is a significant way to communicate to users. Simple and efficent.
Also Tracking on who listened to the voicemail would be nice, but not necessary.
This would be an Admin portal feature only. A recorded file would be uploaded and distributed.