To install on windows uncommenting the dll in php.ini is not enough you also need to include several other libraries in your system path (not user path). Found these details here: http://stackoverflow.com/a/6086991/819883
--enable-intl habilitará a extensão ao compilar o PHP.
Se a ICU estiver instalada em um diretório fora do padrão, sua localização
pode ser especificada na variável de ambiente
LD_LIBRARY_PATH
para que o vinculador dinâmico possa encontrá-lo:
Caso o PHP e a ICU estejam instalados em suas localizações padrão, as opções adicionais para o comando configure não são necessárias.
To install on windows uncommenting the dll in php.ini is not enough you also need to include several other libraries in your system path (not user path). Found these details here: http://stackoverflow.com/a/6086991/819883
On XAMPP (Windows) open the php.ini by opening the control panel, selecting config on apache section and selecting PHP
Then add extension=php_intl and restart Apache
For amazon nginx server (CentOs), try the following:
sudo yum install libicu-devel
sudo yum install php-intl
On windows servers, open your php.ini (which should be in Program Files/PHP), and simply uncomment the extension.
extension=php_intl.dll
Restart IIS Webserver - done.
On Windows, with Apache server, it might not be enough to uncomment the extension in the php.ini file. You also need to copy icu****.dll files (about five of them) from PHP folder to Apache /bin folder.