On Messenger, in the options box, under sounds, under Messenger Sounds, there are sounds one can choose to alert a user when a contact signs in, or a new there is a new instant message, new email message, or when there is an incoming voice or video call, as well as Live alerts and nudges. Each of these sounds are customize-able. They can be muted, a default sound can be changed to a new sound from a list provided, or a new sound provided by me can be added.