Send sms through GSM modem with random port in PHP

Question

If I have a GSM modem with 6 ports and each port inserted a SIM card,how can I send sms with random port?

Here is a simple code:

  include "php_serial_class.php";

  $serial=new phpSerial();
  $serial->deviceSet("/dev/ttyUSB0");
  $serial->deviceOpen();

  //continue....  

  ?>

So now the sms will sent through Port 1(ttyUSB0).What can I add or edit the script so that it can be sent with random port? Such as if Port 1 is busy or sending other sms then it will change to port 2...

I tried something like this:

  if(!$serial->deviceOpen())
  {
      $serial->deviceSet("/dev/ttyUSB1"); 
  }

and it won't works.. Thanks in advance.

Answer 1

You wouldn't know if device is busy unless you try to open it, so you have to check it one step with deviceOpen method. Example:

$ports = range(0,5);
shuffle($ports);

$serial = new phpSerial();

foreach($ports as $port){
    if($serial->deviceSet("/dev/ttyUSB{$port}")){
        if($serial->deviceOpen()){
            // send sms
            break; // break the loop after sending sms
        }
    }
}