Presence Indicator is the ability to detect another user’s availability. A user’s availability is indicated by the colored icon beside their profile picture. This availability status is known as your presence and will indicate a status such as Available, Busy, Away, Do Not Disturb, etc. Your presence indicator will effect which communication options are available. This feature shows you whether your contact is available, busy, in a meeting, on a call, or away. This saves you time and allows you to change how you decide to contact them.
Presence is only indicated for those with the Skype for Business (Talk+ client running), otherwise it will show as Offline (uncolored).