http://www.howtoforge.com – How To Use Multiple PHP Versions (PHP-FPM & FastCGI) With ISPConfig 3 (Ubuntu 12.04 LTS) Since ISPConfig 3.0.5, it is possible to use multiple PHP versions on one server and select the optimal PHP version for a website. This feature works with PHP-FPM (starting with PHP 5.3) and FastCGI (all PHP 5.x versions). (HowTos)