Validate Italy mobile phone numbers

phoneOperator.php

/**
* @author mocanuga  
* @desc Return the operator for a phone number for Italy
* @return string
*/
function phoneOperator ($phone) {
    if(!preg_match('/((313)|(3[2-9]{1}[0-9]{1}))([0-9]{7})/', $phone)) // invalid Italy mobile number
    	return 'unkown';
    $mobileOperators = array(
	'/^313/' => 'Rete Ferroviaria Italiana',
	'/^32/' => 'Wind Italy',
	'/^33/' => 'TIM',
	'/^34/' => 'Vodafone Italy',
	'/^35/' => 'Future full-MVNO',
	'/^36/' => 'TIM',
	'/^37/' => 'Various ESP/MVNO',
	'/^38/' => 'Wind Italy',
	'/^39/' => 'H3G Italy'
    );
    $operatorKey = array_filter(array_keys($mobileOperators), function ($operator) use ($phone) {
	return preg_match($operator, $phone);
    });
    return !empty($operatorKey) ? $mobileOperators[array_shift($operatorKey)] : 'unknown';
}