Most Cisco phones have an integrated screenshot function. You can get the screenshot via the phone's webserver.

Authentification must be configured and set up!

Screenshots are at http://phone-ip/CGI/Screenshot

The phone will return a CiscoIPPhoneImage object with the screenshot in CIP format. With cip2gif.exe from the Cisco IP phone services SDK you can convert this into a gif-file.

Screenshots of phones might come in handy when debugging stuff!