How to send SMS to mobiles though C# Asp.net?

See more:

ASP.NET

C#3.5

I want to send sms to mobiles in asp.net application. I have registered on site2SMS site. I have written the below code to establish this. But it is generating an error like

" The remote server returned an error: (403) Forbidden.webclient"


the code is:

using ASPSnippets.SmsAPI;

 protected void btnSend_Click(object sender, EventArgs e)
      {
          SMS.APIType = SMSGateway.Site2SMS;
          SMS.MashapeKey = "<Mashape API Key>";
          SMS.Username = txtNumber.Text.Trim();
          SMS.Password = txtPassword.Text.Trim();
          if (txtRecepientNumber.Text.Trim().IndexOf(",") == -1)
          {
              //Single SMS
        ///      SMS.SendSms(txtRecepientNumber.Text.Trim(), txtMessage.Text.Trim());
              SMS.SendSms(txtRecepientNumber.Text, txtMessage.Text);
          }

}

Pls give me a reply.