This chapter contains sections titled:

• Overview of the Presence Service

• The Presence Life Cycle

• Presence Subscriptions and Notifications

• Presence Publication

• Presence Information Data Format (PIDF)

• The Presence Data Model for SIP

• Mapping the SIP Presence Data Model to the PIDF

• Rich PIDF

• CIPID

• Timed Presence Extension to the PIDF

• Presence Capabilities

• Geographical Location in Presence

• Watcher Information

• Watcher Authorization: Presence Authorization Rules

• URI-list Services and Resource Lists

• Presence Optimizations