var values = new NameValueCollection();
values["clientId"] = clientId;
values["clientIP"] = currentIP;

byte[] response;
var resultResponse = string.Empty;

using (var client = new WebClient())
{
    try {
            response = client.UploadValues(url, values);
            resultResponse = Encoding.Default.GetString(response);
        }
    catch (WebException e)
        {
            string exception = string.Empty;
            if (e.Status == WebExceptionStatus.ProtocolError)
            {
                exception += ((HttpWebResponse)e.Response).StatusCode;
                exception += ((HttpWebResponse)e.Response).StatusDescription;
            }
        }
    }

string method = "post";
            WebRequest req = WebRequest.Create(uri);
            req.ContentType = contentType;
            req.Method = method;
            req.Headers.Add("myhead", value);

            req.ContentLength = jsonDataBytes.Length;
            var stream = req.GetRequestStream();
            stream.Write(jsonDataBytes, 0, jsonDataBytes.Length);
            stream.Close();
            var response = req.GetResponse().GetResponseStream();
            StreamReader reader = new StreamReader(response);
            var res = reader.ReadToEnd();
            reader.Close();
            response.Close();
            return res;