I’ve decide to go away from phpBB3 as applying mod is a joke, it require you to patch/edit php file manually while in SMF, it is a plugin.
Migrate your forums from phpBB3 to SMF
Download the converter convert.php at http://www.simplemachines.org/community/index.php?topic=218449.0 and save it in the root folder of a new SMF installation.
Backup your SMF/phpBB3 databases and files just in case something bad happen.
The conversion tools is really powerful and support luckily a huge list of forums:
Download the right convert SQL file from
php convert.php --path_to=/srv/www/vhosts/forums/httpdocs/smf --path_from=/srv/www/vhosts/forums/httpdocs/phpbb3 --convert_script=phpbb3_to_smf.sql --db_pass=xxxxxxxxxxxxx --debug