docs: @Override
      public String sendSMS(String CorpNum, String sender, String content,
                            Message[] Messages, Date reserveDT, Boolean adsYN, String UserID, String requestNum)
              throws PopbillException {
          return sendMessage(MessageType.SMS, CorpNum, sender, null, null, content,
                  Messages, reserveDT, adsYN, UserID, requestNum);
      }