When you create code from a WSDL file using SvcUtil.exe, among the many types created is an interface that derives from both the service interface and IClientChannel.
If, for example, the created service interface is called IMyService, it also creates this interface:
public interface IMyServiceChannel :
IMyService, System.ServiceModel.IClientChannel
Why does it define this interface? As far as I can see, it's not referenced from anywhere in the auto-generated code.