i don't know much about the tools that are being used but i do know that they do monitor hrs of the modem on line and yes they use the packet loss to monitor the modems from what i understand the tools update every 15 min and when you look at the results you can tell by the packet loss of all the modems in the nodes and you will see which modems have high packet loss and there for you can start your process of elimination if you have 1 modem with high packet loss possibly bad drop if you have several modems then possibly dist or trunk issue hope this helps