HttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("https://rest.sendmode.com/v2/hlr");
httppost.setHeader(HttpHeaders.AUTHORIZATION, YOUR_ACCESS_KEY);

List<NameValuePair> params = new ArrayList<NameValuePair>(1);
params.add(new BasicNameValuePair("mobilenumber", "0870000000"));
httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();