Send post Http request with Content Type application Json on C#

public bool SendSms1(string sms, string mob, string aport)
{
    bool flag = false;
    string userName = "admin";
    string passWord = "admin";
    try
    {
        string Url = ConfigurationSettings.AppSettings["url1"].ToString();



        HttpWebRequest httpWReq = (HttpWebRequest) WebRequest.Create(Url);

        Encoding encoding = new UTF8Encoding();
        // string postData = "{\"data\":{\"number\":\"" + arrMobile + "\",\"text\":\"" + sms + "\"},\"port\":\"" + arrPort + "\"}}";
        string postData = "{\"number\":[\"" + mob + "\"],\"text\":\"" + sms + "\",\"port\":[\"" + aport + "\"]}";
        byte[] data = encoding.GetBytes(postData);

        httpWReq.ProtocolVersion = HttpVersion.Version11;
        httpWReq.Method = "POST";
        httpWReq.ContentType = "application/json"; //charset=UTF-8";
        //httpWReq.Headers.Add("X-Amzn-Type-Version",
        // "[email protected]");
        //httpWReq.Headers.Add("X-Amzn-Accept-Type",
        // "[email protected]");

        string _auth = string.Format("{0}:{1}", userName, passWord);
        string _enc = Convert.ToBase64String(Encoding.ASCII.GetBytes(_auth));
        string _cred = string.Format("{0} {1}", "Basic", _enc);
        //httpWReq.Headers.Add(HttpRequestHeader.Authorization,
        // "Bearer " + accessToken);

        httpWReq.Headers[HttpRequestHeader.Authorization] = _cred;
        httpWReq.ContentLength = data.Length;


        Stream stream = httpWReq.GetRequestStream();
        stream.Write(data, 0, data.Length);
        stream.Close();

        HttpWebResponse response = (HttpWebResponse) httpWReq.GetResponse();
        string s = response.ToString();
        StreamReader reader = new StreamReader(response.GetResponseStream());
        String jsonresponse = "";
        String temp = null;
        while ((temp = reader.ReadLine()) != null) {
            jsonresponse += temp;
        }
        return true;
    }
    catch (WebException e)
    {

        using(WebResponse response = e.Response)
        {
            HttpWebResponse httpResponse = (HttpWebResponse) response;
            Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
            using(Stream data = response.GetResponseStream())
            using(var reader = new StreamReader(data))
            {
                string text = reader.ReadToEnd();
                Console.WriteLine(text);
            }
        }
        return flag;
    }
}