Question

I want to make a c# program that connects to my mobile phone by usb cable to make just a call. I found how to connect by SerialPort and how to make call by AT Commands, but when I run my program and click to make the call, nothing happens. This is my code, please Help me:

SerialPort SP = new SerialPort("COM3");
SP.BaudRate = 9600;
SP.Parity = Parity.None;
SP.DataBits = 8;
SP.StopBits = StopBits.One;
SP.RtsEnable = true;
SP.DtrEnable = true;
SP.Encoding = System.Text.Encoding.Unicode;
SP.ReceivedBytesThreshold = 1;
SP.NewLine = Environment.NewLine;
SP.Open();
SP.Write("ATDT 0999182542"+ Environment.NewLine);

SP.Close();

Answer 1

First of all to see if your modem is connected, send an AT command to the port. If you get a OK as response, then it means your modem is connected.

To make a call the syntax is:

ATDYourphnumber; //Donot forget the “;”

Example: ATD9012345645;

So you should write to the port the same way.

Syntax:

SP.WriteLine("ATD"+phonenumber+";");

You can use WriteLine since that serves the \r\n too.

Update: How to see the response from modem:

After SP.Open( ) ;

string cmd = "AT";
SP.WriteLine(cmd + "\r");
SP.Write(cmd + "\r");
Thread.Sleep(500);
string ss= SP.ReadExisting();
if(ss.EndsWith("\r\nOK\r\n"))
  {
   MessageBox.Show("Modem is connected");
  }