title: get AT command call response
body: <p>I'm trying a code to make a voice call using usb modem and it succeeded to make a call... now i want to get that call response to know if number is ringing,busy or unavailable</p>
  
  <p>This is my used code:</p>
  
  <pre><code>      string number = textBox1.Text;
  
          po.PortName = "COM3";
          po.BaudRate = int.Parse("9600");
          po.DataBits = Convert.ToInt32("8");
          po.Parity = Parity.None;
          po.StopBits = StopBits.One;
          po.ReadTimeout = int.Parse("300");
          po.WriteTimeout = int.Parse("300");
          po.Encoding = Encoding.GetEncoding("iso-8859-1");
          po.Open();
          po.DtrEnable = true;
          po.RtsEnable = true;
          po.Write("ATDT "+number+";\r"); 
  
          System.Threading.Thread.Sleep(7000);
  
          po.WriteLine("ATH+CHUP;\r");
          po.DiscardInBuffer();
          po.DiscardOutBuffer();
          po.Close();
  </code></pre>