protected void Send_Request_SOAP(string Method, string Param1, string Param2)
        {

            strRequest = @"<s:Envelope xmlns:a=""http://www.w3.org/2005/08/addressing"" xmlns:s=""http://www.w3.org/2003/05/soap-envelope"">" +
                @"  <s:Body>" +
                @"    <{0}>" +
                @"      <x>{1}</x>" +
                @"      <y>{2}</y>" +
                @"    </{0}>" +
                @"  </s:Body>" +
                @"</s:Envelope>"; 
            

            
            strRequest = string.Format(strRequest, Method, Param1, Param2);
            txt_Request.Text = strRequest;

            UTF8Encoding encoding = new UTF8Encoding();
            byte[] data_request = encoding.GetBytes(strRequest);

            string strXMLresponse = "";

            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://localhost/WCFCalc/SOAPCalc.svc");
            myRequest.Method = "POST";
            myRequest.ContentType = "application/soap+xml; charset=utf-8";
            myRequest.ContentLength = data_request.Length;
            Stream newStream = myRequest.GetRequestStream();

            // Send the data.
            newStream.Write(data_request,  0 , data_request.Length);
            newStream.Close();

            StreamReader streamRead ;
            Stream streamResponse;
            HttpWebResponse myHttpWebResponse;

            try
            {
                myHttpWebResponse = (HttpWebResponse)myRequest.GetResponse();  // ВОТ тут ОШИБКА: The remote server returned an error: ( 500 ) Internal Server Error.

                streamResponse = myHttpWebResponse.GetResponseStream();
                streamRead = new StreamReader(streamResponse);
                Char[] readBuffer = new Char[ 256 ];
                // Read from buffer
                int count = streamRead.Read(readBuffer,  0 ,  256 );

                while (count >  0 )
                {
                    String resultData = new String(readBuffer,  0 , count);
                    strXMLresponse = strXMLresponse + resultData;
                    count = streamRead.Read(readBuffer,  0 ,  256 );
                }
                streamRead.Close();
                streamResponse.Close();

                myHttpWebResponse.Close();

                txt_Response.Text = txt_Response.Text +  strXMLresponse;
            }
            catch (Exception exp)
            {
                txt_Response.Text = txt_Response.Text + Environment.NewLine + "error: " + exp.Message;
            }

        }

POST /WCFCalc/SOAPCalc.svc HTTP/ 1 . 1 
Content-Type: application/soap+xml;  charset=utf- 8 
Host: vlad
Content-Length:  195 
Expect:  100 -continue

<s:Envelope xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:s="http://www.w3.org/2003/05/soap-envelope">  
<s:Body>    <Add>      <x> 41 </x>      <y> 52 . 34 </y>    </Add>  </s:Body>
</s:Envelope>

HTTP/ 1 . 1   500  System.ServiceModel.ServiceActivationException
Date: Tue,  26  Jan  2010   09 : 26 : 44  GMT
Server: Microsoft-IIS/ 6 . 0 
X-Powered-By: ASP.NET
X-AspNet-Version:  2 . 0 . 50727 
Cache-Control: private
Content-Length:  0