# yum search php-intl --enablerepo=epel,remi-safe,smecontribs
php-intl.x86_64 : Internationalization extension for PHP applications
php54-php-intl.x86_64 : Internationalization extension for PHP applications
php55-php-intl.x86_64 : Internationalization extension for PHP applications
php56-php-intl.x86_64 : Internationalization extension for PHP applications
php70-php-intl.x86_64 : Internationalization extension for PHP applications
php71-php-intl.x86_64 : Internationalization extension for PHP applications
php72-php-intl.x86_64 : Internationalization extension for PHP applications
php73-php-intl.x86_64 : Internationalization extension for PHP applications
so depending on your php version , base is in epel, php-scl is in remi-safe or snmecontribs repos