//پیش نیاز using System.Net; //نمونه کد var request = (HttpWebRequest)WebRequest.Create("http://sms321.ir/webservice/rest/sms_send?"); var postData = "login_username=USERNAME&login_password=PASSWORD&receiver_number=09132677411¬e_arr[]=سلام&sender_number=10007666"; var data = Encoding.ASCII.GetBytes(postData); request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = data.Length; using (var stream = request.GetRequestStream()) { stream.Write(data, 0, data.Length); } var response = (HttpWebResponse)request.GetResponse(); var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();