old-new-wiaas/backend/app/plugins/wiaas/includes/class-wiaas-validation.php

<?php

defined( 'ABSPATH' ) || exit;

/**
 * Class Wiaas_Validation
 */
class Wiaas_Validation {

    public static function is_phone($phone){
        return WC_Validation::is_phone($phone);
    }
}