title: WCF Client - 407 Proxy Authentication Required while running webservice
body: <p>I've created simple WinForms app that uses free webservice <a href="http://www.webservicemart.com/uszip.asmx" rel="noreferrer"><b><a href="http://www.webservicemart.com/uszip.asmx" rel="noreferrer">http://www.webservicemart.com/uszip.asmx</a></b></a>. But this app fails to use service operation with error:</p>
  
  <blockquote>
    <p>The remote server returned an unexpected response: (407) Proxy Authentication Required (The ISA Server requires authorization to fulfill the request. Access to the Web Proxy service is denied)</p>
  </blockquote>
  
  <p>Code that creates proxy and triggers service operation:</p>
  
  <pre><code>ChannelFactory&lt;ServiceReference1.USZipSoap&gt; proxy = new ChannelFactory&lt;ServiceReference1.USZipSoap&gt;("USZipSoap");
  ServiceReference1.USZipSoap client = proxy.CreateChannel();
  string str = client.ValidateZip("12345");
  MessageBox.Show(str);
  </code></pre>
  
  <p>Is this problem with a network of my company or this is a proxy on the side of <a href="http://www.webservicemart.com" rel="noreferrer"><b>webservicemart.com</b></a>?</p>
  
  <p>I've googled a lot of information on changing configuration files, creating a custom binding, etc. But I feel the lack of more basic understanding...<br> If this error is about ISA server of our corporate network then what configuration should I make to ISA Server to not restrict me from using external webservices?</p>