ELMAH – Exception Logging without having HttpContext

I’m answering my own question.

I tried adding following in my web.config

<system.serviceModel>
  <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
</system.serviceModel>

Also decorated my Service with following attribute

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]    
public class CalculatorService : ICalculatorSession    
{
    // Implement calculator service methods
 }

Still no use.
Then I got the solution here by which you can use Elmah without HTTPContext. i.e. log errors by writing

Elmah.ErrorLog.GetDefault(null).Log(new Error(ex));

instead of

Elmah.ErrorSignal.FromCurrentContext().Raise(error);