I've done quite a bit of research on this. If you are running CCM v5/6 (the Linux based version) and you are using MGCP to manage your 2x00, 3x00 based gateways the only way I found to get PRI/T1 CAS/BRI usage data is via the AXL SOAP interface. This is the same method the Cisco RTMT uses and it is currently the only method Cisco supports (opened a TAC case) to collect info on MCGP based GW interfaces. SolarWinds would have to look at using the AXL SOAP interface to do this. There are only a few tools on the market that will grab this data for you via this method (this was the path we went down and fortunately its the same tool we use for all our servers).
If you're interested in coding something to take advantage of the Cisco AXL SOAP interface, go to the following link and select "CallManager - AXL SOAP API" from the "Unified Communications and Location Technology" drop-down. I haven't gotten into it yet, as we're just now moving to v8.x of Orion, but we will be looking into it soon.
