title: How to execute AT commands into the serial port in java?
body: <p>I have device which connected to the modem using a serial port, which has two SIMs. I have received a requirement to get the IMSI number of these SIMs from the modem. I heard it can be retrieved by giving the AT command "AT+CIMI" to the modem. My question are:</p>
  
  <ul>
  <li>How is the AT command given to the modem</li>
  <li>if it is possible to retrieve the IMSI number in any other way. </li>
  <li>Are there any libraries to execute the the AT commands</li>
  </ul>