private string SMSGlobalData(string username, string password, string source, string destination, string text)
{

      System.Text.StringBuilder postData = new System.Text.StringBuilder("action=sendsms");
      postData.Append("&user=");
      postData.Append(System.Web.HttpUtility.UrlEncode(username));
      postData.Append("&password=");
      postData.Append(System.Web.HttpUtility.UrlEncode(password));
      postData.Append("&from=");
      postData.Append(System.Web.HttpUtility.UrlEncode(source));
      postData.Append("&to=");
      postData.Append(System.Web.HttpUtility.UrlEncode(destination));
      postData.Append("&text=");
      postData.Append(System.Web.HttpUtility.UrlEncode(text));

      return postData.ToString();

}

private string SendSms(string url, string postData)
{

      System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
      byte[] data = encoding.GetBytes(postData);

      HttpWebRequest smsRequest = System.Net.WebRequest.Create(url);
      smsRequest.Method = "POST";
      smsRequest.ContentType = "application/x-www-form-urlencoded";
      smsRequest.ContentLength = data.Length;

      System.IO.Stream smsDataStream = null;
      smsDataStream = smsRequest.GetRequestStream();
      smsDataStream.Write(data, 0, data.Length);
      smsDataStream.Close();

      System.Net.WebResponse smsResponse = smsRequest.GetResponse();

      byte[] responseBuffer = new byte[smsResponse.ContentLength];
      smsResponse.GetResponseStream().Read(responseBuffer, 0, smsResponse.ContentLength - 1);
      smsResponse.Close();

      return encoding.GetString(responseBuffer);

}