NCM handles Cisco inventory wonderfully except it does not do anything with Cisco phones. We have thousands that we would like to inventory. It would make NCM complete for us if it did.
Since they are not SNMP devices discovery and information capture takes a different route. I found a tool by UPLINX that queries CallManager for a list of phones and queries phones I think through their HTTP page for all the rerquired info. Cisco has a similar tool but it does a whole lot of other things and I am sure it is costly.
Again if NCM could do something like UPLINX it would be awesome, even if it was an additional module that cost extra.