public static function FILTER_SANITIZE_TELEPHONE($value)
	{
		$value = preg_replace('/^[^0-9+]+/', '', $value);  		// remove all from beginning execept numbers and +
		$value = preg_replace('/^\+39/', '', $value);  			// remove +39 prefix		
		$value = preg_replace('/^0039/', '', $value);  			// remove 0039 prefix
		$value = preg_replace('/[\s\(\)]+/', '', $value);  		// remove all blanks and parenthesis
				
		// separate number from extensions (if any)
		if( preg_match('/([0-9]+)(.*)/', $value, $matches)){
			$value = $matches[1];
			$extension = preg_replace('/[^0-9]/', '', $matches[2]);;
			if($extension){
				$value .= " [$extension]";
			}			
		}					

		return $value?:null;		
	}