Tonia, not sure what happened to the link, my apologies.
The easiest way to locate the information I am referring to is to open Prognosis online help and go to 'Prognosis for Unified Communications > Cisco Unified Communications Manager > Configuration > Cisco Setup > Set SNMP Credentials'
Prognosis captures phone counts from a different source than it captures the up/down status. We use SOAP/AXL queries to pull information from the call manager which gives us counts from the cluster database.
We correlate this with SNMP data received from the publisher and subscribers to paint the "bigger picture" of what's going on within the cluster. We also make use of CDR/CMR data to add voice quality metrics into the picture.
Although Prognosis may be able to communicate on some of the above mechanisms, we need all in place to show a full level of visibility.