This actually depends on your local franchise. Some franchises do not specify whether or not you can run a server that is internet accessible. Most franchises do not allow this action - but, you will need to check with your local RR franchise for more information.
Most contributors here at BroadBand Reports seem to indicate that low bandwidth
servers seem to be generally tolerated by most franchises - things like role-playing games (WoW for example).
However, a sure way to attract attention to your account is to run a server that is pushing out a LOT of upstream bandwidth (e.g. serving files to others)....