If you need to reach a Web Service and you are behind a proxy server, you have to set some Proxy values. When you add a Web Reference in your project to query a Web Service, Visual Studio .NET creates a class that inherits from System.Web.Services.Protocols.SoapHttpClientProtocol. This class has a property called Proxy that enables you to set proxy information for making an XML Web service request through a firewall. Then, you have to specify a user to log on the proxy server using the System.Net.NetworkCredential class.

string ProxyHost = "192.168.0.201" //The name of the proxy hostint ProxyPort = "80"; //The port number on Host to usestring ProxyUser = ""; //The user name associated with the credentialsstring ProxyPassword = ""; //The password for the user name associatedwith the credentialsstring ProxyDomain = ""; //The domain associated with these credentials//Create a new WebProxy objectSystem.Net.WebProxy oWebProxy = new System.Net.WebProxy(ProxyHost,ProxyPort);//Create a new NetWorkCredential to authenticate the user in the ProxyServer.oWebProxy.Credentials = new NetworkCredential( ProxyUser, ProxyPassword,ProxyDomain);//Set the Proxy property of your Web Service Client object.objWebService.Proxy = oWebProxy;