Get the latest packages. up to 2014-02-10

# rpm -Uvh http://packages.asterisk.org/centos/6/current/x86_64/RPMS/asterisknow-version-3.0.1-2_centos6.noarch.rpm
# yum install asterisk asterisk-configs --enablerepo=asterisk-12
# yum install dahdi-linux dahdi-tools libpri
# chkconfig dahdi on
# chkconfig asterisk on
# service dahdi start
# service asterisk start

You can use freepbx on http://localhost .

# yum install freepbx