1. In buffer access mode, if the buffer is not empty, the module will not report a new URC until all the
received data has been read via AT+QIRD from buffer.
2. In transparent access mode, AT commands cannot be executed. If the socket connection is closed
because of network error or other errors, the module will report NO CARRIER and exit from the
transparent access mode. In this case, AT+QICLOSE should be executed to close the socket
service.