title: COM port not opened in PHP
body: <p>I am reading SMS from GSM modem using PHP and storing them in database. Modem is connected to my machine using Serial to USB converter cable. This is working fine with one modem which is connected to <strong>COM3</strong>.</p>
  
  <p>I am using <a href="https://gist.github.com/NapsterC/a217adc9a689048cc41d" rel="nofollow">SMS.php class</a>.</p>
  
  <p>Now when I am trying to use same code for another modem connected at <strong>COM23</strong> or any other port. It's not even opening port.</p>
  
  <p>I tried using <strong>\\.\COM23</strong> but that too didn't work.</p>
  
  <p>The modems are from two different manufacturers, I have installed required drivers too.</p>
  
  <p>What could be the issue?</p>
  
  <p>Please help.</p>
  
  <p>Thanks</p>