Yep you are right because Hibernate has restrictions, which is based on Oracle's JDBC driver not implementing to the spec/standard. (Sorry Michael, not directed at you there )
In order to work with Stored Procedures here are the rules
1. You can only have one out parameter 2. That out parameter must be the first parameter 3. That out parameter must be a ref-cursor.
Say you want to call a stored procedure that does not follow those rules, well then you would have to use a SQLQuery object and call the stored procedure is a different manner like in Oracle you can call "select myProcedure(param1, param2) from dual"