Presence State reflects the current state of the user of the device. Presence states available within Asterisk are as follows:
not_set: No presence state has been set for this entity.
unavailable: This entity is present but currently unavailable for communications.
available: This entity is available for communications.
away: This entity is not present and is unable to communicate.
xa: This entity is not present and is not expected to return for a while.
chat: This entity is available to communicate but would rather use instant messaging rather than speaking.
dnd: This entity does not wish to be disturbed.
In addition to the basic presence states provided, presence also has the concept of a subtype and a message.
The Subtype is a brief method of describing the nature of the state. For instance, a subtype for the away status might be "at home".
The message is a longer explanation of the current presence state. Using the same away example as before, the message may be "Sick at home. Out until tomorrow".