The change is due to a user going offline.
Also used when user is already offline, but this wasn't known previously. If a one-to-one StreamedMedia call fails because the contact being called is offline, the connection manager SHOULD indicate this by removing both the SelfHandle and the other contact's handle from the Group interface with reason Offline. For 1-1 calls, the call terminates as a result of removing the remote contact, so the SelfHandle should be removed at the same time as the remote contact and for the same reason. If a handle is removed from a group for this reason, the equivalent D-Bus error is org.freedesktop.Telepathy.Error.Offline.