title: org.smslib port in use exception
body: <p>I am trying to create web application to send sms by gsm modem in JSP first I put destination mobile number and sms text in url and get by request.getparameter and first message sent with no problem but when send a message again by referenshing the same page i get this exception:</p>
  
  <pre><code>org.smslib.GatewayException: Comm library exception: java.lang.RuntimeException: gnu.io.PortInUseException: org.smslib
      at org.smslib.modem.SerialModemDriver.connectPort(SerialModemDriver.java:102)
      at org.smslib.modem.AModemDriver.connect(AModemDriver.java:114)
      at org.smslib.modem.ModemGateway.startGateway(ModemGateway.java:189)
      at org.smslib.Service$1Starter.run(Service.java:276)
  </code></pre>
  
  <p>I tried to stop gateway and stop service but no hope
  My code:</p>
  
  <pre><code>public boolean sendMessage(String strMobileNo,String strSMSText)
      {
          try
          {   
              OutboundMessage outboundMessage=new OutboundMessage();
              SMS message=new SMS();
              SerialModemGateway gateway = new SerialModemGateway("modem.com1", "COM12", 9600, "Huawie", "EF200");
              gateway.setInbound(true);
              gateway.setOutbound(true);
              gateway.setSimPin("0000");
              gateway.setSmscNumber("+9647701144010");
              Service.getInstance().setOutboundMessageNotification(message);
              Service.getInstance().addGateway(gateway);
              Service.getInstance().startService();
              outboundMessage.setText(strSMSText);
              outboundMessage.setRecipient(strMobileNo);
              outboundMessage.setEncoding(Message.MessageEncodings.ENCUCS2);
              //outboundMessage.setDeliveryDelay(5000);
              Service.getInstance().sendMessage(outboundMessage);
              System.out.println(outboundMessage);
              gateway.stopGateway();
              Service.getInstance().stopService();
              Thread.sleep(10000);
              return true;
          }
          catch (Exception e)
          {
              e.printStackTrace();
              return false;
      }
      }
  </code></pre>