USB modem serial port
<p>I have made an application that is depends on connecting to a serial port then reciving SMS and reading it from GSM module  by C#. When i run this code by GSM module it works well but when i run this code by USB module it dosen't see the SIM card and when i connect to the port that USB operates on it  tell me that the requested port is usd and the other ports not work well. the recived SMS appears on the USB application only  </p>

<p>how can i work on the same port that USB operate on or how can i prevent USB to read SMS by its application
can </p>
