Presence (SIP)

A SIP event package that conveys the availability status (online, busy, away, do not disturb) of a user agent, used by instant messaging and unified communications platforms. Presence uses the SUBSCRIBE/NOTIFY mechanism — clients subscribe to a presentity's presence URI and receive NOTIFY messages with PIDF (Presence Information Data Format) XML bodies when the status changes. Rich presence can include location, activity, and mood alongside basic availability.