Sometimes on hosting WCF service on IIS7.0 you might receive the following error

HTTP Error 404.3 – Not Found

The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map. Detailed Error InformationModule StaticFileModule.

This happens when IIS7.0 doesn't know how to handle the .svc files. To fix this we need to register WCF with IIS7.0, following are the steps:

1. Run Visual Studio 2008 Command Prompt as “Administrator”.
2. Navigate to C:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation.
3. Run this command servicemodelreg –i.

The servicemodelreg is a command line tool which provides the ability to manage the registration on ServiceModel on a machine. There is more info on this commans on MSDN here.