How to send message to whatsapp from .NET/C# ?

See more:

C#

I am trying to send message to WhatsApp using my dotnet application and i am trying to send it this way as i have coded, but to send the message we need to register the from/senders number on WART.

But while registering the number it is getting failed to register,showing old resaon "old version".

I think now no longer this method of registration is working.

can any one tell me:
1) The alternative for WART.

or

2) Any other working method to send message to any WhatsApp number through Dot Net application and c#

What I have tried:

protected void Unnamed4_Click(object sender, EventArgs e)
        {
            string from = "91**********";
            string to = tonumber.Text;
            string msg = message.Text;

            WhatsAppApi.WhatsApp wa = new WhatsAppApi.WhatsApp(from, "S2pRzjF5WnVc***********", "namofsender", false, false);

            wa.OnConnectSuccess += () =>
            {
                message.Text = "success";

                wa.OnLoginSuccess += (phonenumber, data) =>
                  {
                      wa.SendMessage(to, msg);
                      message.Text = "Sent";
                  };


                wa.OnLoginFailed += (data) =>
                  {
                      message.Text = "Failed";
                  };

                wa.Login();
            };

            wa.OnConnectFailed += (ex) =>
              {
                  message.Text = "connection failed";
              };

            wa.Connect();
        }