code: function _detectFeaturePhoneCarrier(ua) {
      switch (true) {
      case /DoCoMo/.test(ua):             return "DOCOMO";
      case /KDDI/.test(ua):               return "KDDI";
      case /SoftBank|Vodafone/.test(ua):  return "SOFTBANK";
      }
      return "";
  }
docs: --- feature phone ---------------------------------------