I imagine it is is one of the logs, but I don't know which. It might also require that you enable a higher level of debug. I would guess it would be in the call manager logs, but it may have been overwritten depending on the activity level of your system and how long ago it was set. Perhaps you could look in the status of event logs of the phone itself if the web server is enabled. Sorry to not be more specific, but I have never had to look for this before.
