making call from gsm modem in C#

Question

I want to make a call from a GSM modem using C#. I have written the following code. but I am unable to make the call. Please tell what the mistake is. Also let me know how to handle the response in the code from the modem so that I can display a message like "call connecting" or "cannot connect".

private void button1_Click(object sender, EventArgs e)  
{  
    SerialPort po = new SerialPort();  
    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.DataReceived += new SerialDataReceivedEventHandler(port_DataReceived);  
    po.Write("ATD9030665834;");  
}  
public void port_DataReceived(object sender, SerialDataReceivedEventArgs e)  
{  
    if (e.EventType == SerialData.Chars)  
    {  
            //what to write here to display the response??    
    }  
}  

Answer 1

Use port.WriteLine("ATD"+phno+";");

This will definitely solve your problem..

And to handle the response use port.ReadExisting() and compare with your requirement. As easy as that :)

Good luck..

Answer 2

1. Make Sure whether you are configuring po same as Hyper-terminal as it is working with Hyperterminal. Hyper Terminal settings are usually like:

If it has Flow Control as NONE then You don't need:

po.DtrEnable = true;         
  po.RtsEnable = true;  

I don't find use of Setting encoding.

Most important thing You are forgetting is Add "\r" at the end of Any AT Command! Seems you haven't read AT Command list!

Answer 3

private void button1_Click(object sender, EventArgs e)
        {
            SerialPort po = new SerialPort();
            po.PortName = "COM10";
            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.DataReceived += new SerialDataReceivedEventHandler(port_DataReceived);
           // po.Write("ATD01814201013;");
            po.WriteLine("ATD01"+textBoxPhoneNumber.Text+";"+Environment.NewLine);
        }