Multiple Points of Presence

Lync Server presence has the added flexibility of being read from multiple endpoints simultaneously. This enables a user to be signed in at multiple locations or endpoints that publish presence independently. The server then aggregates these endpoints and forms a single presence class that is published to subscribers.

For instance, a user can be signed in to Lync on a desktop, again on a roaming laptop, at home on a Mac, and also on a mobile device. Each of these endpoints publishes presence independently, and the server then forms the user’s presence appropriately.

Having multiple clients signed in is generally considered a problem because how does a user know which endpoint to send a message to? Without multiple points of presence, there is a problem. However, when a user sends another user a message, the Lync Server determines which endpoint is currently most active for that user. For example, a user might be Away at three of the four endpoints, so the server sends the message only to the endpoint where the user is available.

If the server is unable to determine which state is most active, it sends the message to the endpoint it determines most likely active and waits to see whether the user acknowledges the toast at any location. If the user opens the toast at an endpoint, the server removes the message from the other endpoints. If an endpoint doesn’t acknowledge the message, the server leaves the message at only one location, the most likely endpoint.

MPOP might not be perfect at all times, but it does enable a user to publish presence from multiple locations and still receive conversations at the most likely endpoint.