No, if the Call Processing routine finds an extension that does not exist in the station file, it will automatically add the extension for you. You will then have to go back and put the user name and department code on that extension if you decide to use those options.
Depending on how your system was configured, there may be call records in the system that do not have corresponding extension entries in the station file. There is a Wizard that will resolve that by adding any missing extensions that have made call records. You can find information on that wizard here:
Comm One LLC Technical Support
138 E 12300 S Ste C102
Draper, UT 84020