using System;

using System.IO;

using System.Net;

using System.Text;

public class Program

{

    public static void Main()

    {

        WebRequest request = WebRequest.Create("https://gateway.sms77.io/api/sms");

        request.Method = "POST";

​

        string postData = "p=API_KEY&to=" + WebUtility.UrlEncode("43676123456789") + "&text=" + WebUtility.UrlEncode("Hello World") + "&from=" + WebUtility.UrlEncode("Sender ID") + "&debug=0&sendwith=argetherapie";

        byte[] byteArray = Encoding.UTF8.GetBytes(postData);

​

        request.ContentType = "application/x-www-form-urlencoded";

        request.ContentLength = byteArray.Length;

​

        Stream dataStream = request.GetRequestStream();

        dataStream.Write(byteArray, 0, byteArray.Length);

        dataStream.Close();

​

        WebResponse response = request.GetResponse();

​

        using (dataStream = response.GetResponseStream())

        {

            StreamReader reader = new StreamReader(dataStream);

            string responseFromServer = reader.ReadToEnd();

            if(responseFromServer == "100") 

                Console.WriteLine("SMS sent!");

            else

                Console.WriteLine("SMS failed. Error code: " + responseFromServer);

        }

​

        response.Close();

    }

}