title: Serial Port does not receive whole data in C#
body: <p>I am using C# serial port controlling gsm modem. Now in Mikroelectronia USART Terminal 
  after sending:</p>
  
  <blockquote>
    <p>AT+CUSD=1,"*778#",15</p>
  </blockquote>
  
  <p>It receives:</p>
  
  <blockquote>
    <p>AT+CUSD=1,"*778#",15</p>
    
    <p>OK</p>
    
    <p>+CUSD: 0,"Balance: 0.00 TK. Validity: 29-Jul-13. Bonus: 0.00TK. Free Min: 0. Dial *121*2092# for 3 hit songs of Ashiqui-2 as ur Caller
    Tunetk.10",64</p>
  </blockquote>
  
  <p>But in C# after sending data  </p>
  
  <blockquote>
    <p>AT+CUSD=1,"*778#",15</p>
  </blockquote>
  
  <p>it returns:</p>
  
  <blockquote>
    <p>AT+CUSD=1,"*778#",15</p>
    
    <p>OK</p>
    
    <p>+CUSD: 0,"Balance: 0.00 TK. Validity: 29-Jul-13. Bonus: 0.00TK. Free Min: 0. Dial *121*2092# for 3 hit songs of Ashiqui-2 as ur Caller Tune</p>
  </blockquote>
  
  <p>That means in C# it does not receive any data after "Caller Tune". Why is that happening? Part of C# code I have used is</p>
  
  <pre><code>        private void Form1_Load(object sender, EventArgs e)
          {
              sp1.DataReceived += new SerialDataReceivedEventHandler(sp_DataReceived);
          }
  
          void sp_DataReceived(object sender, SerialDataReceivedEventArgs e)
          {
              var valueOfPort = sp1.ReadExisting();
              textBox1.AppendText(valueOfPort);
  
          }
   private void button1_Click(object sender, EventArgs e)
          {
              TextBox.CheckForIllegalCrossThreadCalls = false;
  
              try
              {
  
  
                  if (!sp1.IsOpen)
                  {
                      sp1.Open();
                  }
                  sp1.Write(textBox2.Text+"\r");
  
              }
              catch(Exception ex)
              {
  
                  MessageBox.Show(string.Format("Exception : {0}", ex.Message), "Port Error");
              }
          }
  </code></pre>