Call Categorization

I am currently looking into re-designing my Call Categorization Process that is used each time a representative logs a call or problem. I have already identified the reports I would like to obtain from the Call Categorization, however, I am still having a problem logically devising a proper call categorization structure that is easy to understand. Does anyone have any suggestions for an appropriate layout of a call classification? Also, do you know of any valuable websites that assist IT Managers who are struggling through this process? Any help would be greatly appreciated.