What is Pas?

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You might have seen the event with id 32113 from LS User Services informing that “Pas with FQDN: x.y.z has been detected up” and wondered what Pas is?

Pas or PAS stands for Presence Agent Server and is the component of the Lync Server handling presence logic and traffic. Some of the tasks performed by PAS are:

  • Handles incoming presence state changes for users and distribute them to end-points watching the users
  • Presence state aggregation, i.e. a user can be signed in on multiple end-points and the PAS derives the aggregated state from all of a user’s end-points
  • Applies specific ACL to allow or block presence subscriptions, i.e. if you as a user has blocked another user from seeing your presence PAS is the component implementing this

PAS is running in the RTCSRV process and is active on EE front-ends and SE servers, but it is not running on Directors and SBAs.