Cisco doesn't store their phone serial numbers anywhere. So, for companies wishing to obtain SmartNet for their installed base of telephones, there aren't too many ready ways of obtaining those serial numbers, from a first time perspective.
To help one customer out of a bind, I did a couple of very quick and dirty scripts to scan the network for phone devices. I know it works for 7912's, 7940's, 7960's, 7970's and ATA adaptors.
I didn't realize until later that instead of scanning the human readable pages, I could have scanned the xml pages for the information. Oh, well. That will be for the next version.
To operate, you'll need a Perl interpreter and a couple of libraries off CPAN. Then edit findphones.pl and supply the ip address ranges you'd like to scan. Run the script and send STDOUT to a file.
Then run the file through filterphone.pl to get a model number and serial number list.
Cisco's CP-7935 and CP-7936 conference phone serial numbers are simply their mac addresses, which is easy to pull out of Callmanager.