If you are seeing endpoints down in Real Time, there are two potential sources of endpoint information in your environment. The primary source of endpoint status for the endpoints being monitored by Vyopta's Endpoint Monitoring feature is the Vyopta Data Collector. This status is determined by cross referencing the list of active registrations on your call control devices with the aliases as specified on your management system (TMS, CUCM, etc.). If an endpoint is indicated as not available, then that indicates that the registration alias(es) assigned to this endpoint are not showing active registrations across any of your call control devices.
Note: If the endpoint is just turned on and registered to your network, this does not indicate available status because the endpoint must also be registered to a call control device.
If you are interested in deploying Endpoint Monitoring, it can usually be deployed on the existing Data Collector server and activated within minutes. For more information on troubleshooting Cisco Endpoint issues with the new Vyopta Collector 4.6 (and later) and Vyopta Admin Portal (VAP), please refer to this article.