Twilio making call using Dll version 5.3

Question

If we Use the Url as per the Sample Code,it works fine.Here is the Url Used in sample code : ("http://demo.twilio.com/docs/voice.xml") As per the Old Twilio Dll version 3.4 Were making Use of the twimlet Echo to make call i.e("http://twimlets.com/echo?Twiml=%3CResponse%3E%3CSay%3EHi+there.%3C%2FSay%3E%3C%2FResponse%3E"));

And i want to to create to create Stateless apploication,Without application Hosting in any server.

The twimlet echo Url is working fine in version 3.4 and the same URL is not working in 5.3.

        const string accountSid = "ACXXXXXXXXXXXXXXXXXXXXXXXXX";
        const string authToken = "909dajhdusa78798324ndkjsahd";
        TwilioClient.Init(accountSid, authToken);

        var to = new PhoneNumber("+919000000000");
        var from = new PhoneNumber("+919000000000");
        var call = CallResource.Create(to,
                                       from,
                                       url: new Uri("http://twimlets.com/echo?Twiml=test")); //Not working

        call = CallResource.Create(to,
                                       from,
                                       url: new Uri("http://twimlets.com/echo?Twiml=<Response><Say>testing</Say></Response>"));//Not working


        call = CallResource.Create(to,
                                       from,
                                       url: new Uri("http://twimlets.com/echo?Twiml=%3CResponse%3E%3CSay%3EHi+there.%3C%2FSay%3E%3C%2FResponse%3E"));//Not working


        Console.WriteLine(call.Sid);