SP2-1503: Unable to initialize Oracle call interface (11g db upgrade issue)

Issue:

error while running sqlplus command.
[oravis@orafin02 11.2.0]$ sqlplus

SP2-1503: Unable to initialize Oracle call interface
SP2-0152: ORACLE may not be functioning properly

Solution:
[oravis@orafin02 11.2.0]$ cd $ORACLE_HOME/oracore/zoneinfo
[oravis@orafin02 zoneinfo]$
[oravis@orafin02 zoneinfo]$
[oravis@orafin02 zoneinfo]$ ln -s timezone_11.dat timezone.dat
[oravis@orafin02 zoneinfo]$ ln -s timezlrg_11.dat timezlrg.dat
[oravis@orafin02 zoneinfo]$
[oravis@orafin02 zoneinfo]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Sun Apr 7 01:11:35 2013

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL>