MS ODBC for Oracle v 2.573.6526.00
Oracle ODBC Driver v 8.01.57.00

This is working for either set of drivers for me.

To add to what Larry posted, when you are passing no parameters, do not add the () at the end of the call GetWhateverByID.ReturnCursor. For some reason that gives me an error. e.g.:

lcSQL = "{call GetAllPermits.ReturnCursor}"
lnRetval = SQLExec(This.nHandle, lcSQL, 'crsAllPermits')

Where the SP looks like:

CREATE OR REPLACE PACKAGE GetAllPermits AS
 Type RetCursor Is Ref Cursor;
 Procedure ReturnCursor(pCursor OUT RetCursor);
END;
/
show error
CREATE OR REPLACE PACKAGE BODY GetAllPermits AS
 Procedure ReturnCursor(pCursor OUT RetCursor) is
 Begin
  open pCursor for
    select * FROM Permits;
 End;
END;
/
show error