Customisable notifications

Notifications could have different levels of priority for different people and you could set your Do not disturb level, for example 1 to 5.

In a chat channel on a server you could set it so only certain people's messages in that channel would trigger notifications, this would work well with the notification priority levels.

As much as I love the default sounds for calls and notifications, there could be customisable notification and call sounds for people in general and for individual people, that way you could not even look at the notification to know who it is contacting you.