I want to get `Network Interface` on which `HttpWebRequest` was made

I found [WebRequestExtensions.GetCurrentNetworkInterface](http://msdn.microsoft.com/en-us/library/microsoft.phone.net.networkinformation.webrequestextensions.getcurrentnetworkinterface%28v=vs.92%29.aspx) function for this. `HttpWebRequest` also has `GetCurrentNetworkInterface()` method to perform the same.

This is my code:

```
 HttpWebRequest httpWebRequest = HttpWebRequest.CreateHttp(new Uri(Url, UriKind.Absolute)); 
 //this line throws InvalidOperationException       
 NetworkInterfaceInfo i = httpWebRequest.GetCurrentNetworkInterface();

```

I perform method call from UI thread. If I made call after `BeginGetResponse` exception tells "request was finished". What is workaround for this?

Exception info:

Message is `InvalidOperationException` 

StackTrace:

```
  at System.Net.Browser.ClientHttpWebRequest.GetConnectionDetails(IntPtr& Details, Int32& sizeofDetails)
  at Microsoft.Phone.Net.NetworkInformation.WebRequestExtensions.GetCurrentNetworkInterface(WebRequest request)

```