is it possible to prevent conflicts?

Is there a way to either prevent conflicts or warn users that a conflict exists PRIOR to allowing the save of an event? we are using netsuite to schedule customer calls - but the system does not warn users that they are about to book a conflicting call.  The only way I can think of doing a check is with some form of javascript - am I correct or is there a setting in netusite I have not found?

Thanks

Walter
system administrator