///
<summary>/// Url of STS service. Can be overwritten if needed.
/// </summary>
 
private static string UPAuthUrl = "https://sts.idm.telekom.com/rest-v1/tokens/odg";
 
private string username = "username";
private string password = "password";
 
///
<summary>/// Generated by STS service.
/// </summary>
 
private string token;
 
private async void authenticate()
{
 
HttpClientHandler handler = new HttpClientHandler();
handler.Credentials = new NetworkCredential(username, password);
 
HttpClient client = new HttpClient(handler);
 
try
{
HttpResponseMessage response = await client.GetAsync(UPAuthUrl);
// Force an exception if the web server returned an HTTP error status code
response.EnsureSuccessStatusCode();
 
String content = await response.Content.ReadAsStringAsync();
JsonObject json = JsonObject.Parse(content);
token = json.GetNamedValue("token").GetString();
 
// proceed to api call
sendSMS();
}
catch (HttpRequestException hre)
{
Debug.WriteLine(hre.ToString());
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
 
}

///
<summary>/// Realm for authorization.
/// {0} is replaced by authorization token
/// </summary>
 
private static string Realm = "realm=\"https://odg.t-online.de\",tauth_token=\"{0}\"";
 
///
<summary>/// URL Path to Send SMS services. Can be overridden if necessary.
/// {0} is replaced by selected environment (sandbox or production)
/// </summary>
 
private static string ServicePath = "plone/odg-sms/rest/{0}/sms";
 
///
<summary>/// Address of Telekom API server.
/// </summary>
 
private static string TelekomBaseUrl = "https://gateway.developer.telekom.com/";
 
private async void sendSMS()
{
 
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("TAuth", String.Format(Realm, token));
 
Uri baseUri = new Uri(TelekomBaseUrl, UriKind.Absolute);
Uri relativeUri = new Uri(String.Format(ServicePath, "production"), UriKind.Relative);
Uri uri = new Uri(baseUri, relativeUri);
 
MultipartFormDataContent form = new MultipartFormDataContent();
form.Add(new StringContent("+4933123456"), "number");
form.Add(new StringContent("Foo"), "message");
// Optional (see http://www.developergarden.com/fileadmin/microsites/ApiProject/Dokumente/Dokumentation/Api_Doc_4_0/telekom-api-rest-4.0/html/sendsms_send_s_m_s.html)
form.Add(new StringContent("Sascha"), "originator");
 
try
{
HttpResponseMessage response = await client.PostAsync(uri, form);
// Force an exception if the web server returned an HTTP error status code
response.EnsureSuccessStatusCode();
}
catch (HttpRequestException hre)
{
Debug.WriteLine(hre.ToString());
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
 
}