Send Unicode SMS (Hindi, English) using C#

I am sending sms from api ...but message is in hindi..after delivery message is showing ?????????????? like this..plz share any code....

        public static String SMSSend(String Message, String Recipient)
        {
            //string ipAddres = Common.getIPAddress();
            try
            {
                WebClient Client = new WebClient();
                Recipient = Recipient.Trim();
                if (Recipient.Substring(Recipient.Length - 1, 1) == ",")
                    Recipient = Recipient.Substring(0, Recipient.Length - 1);

                
                string baseurl = "http://www.aiet.ac.in/SendSMS?userid=0000&password=00000@&sender=AZADES&mobileno=" + HttpUtility.UrlEncode(Recipient) + "&msg=" + Message;
                Stream data = Client.OpenRead(baseurl);
                StreamReader reader = new StreamReader(data);
                string s = reader.ReadToEnd();
                data.Close();
                reader.Close();
                return s;

            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }