handler   _In_
Type: XblCallRoutedHandlerThe event handler function to call. This parameter must not be null.context   _In_opt_
Type: void*Caller context to be passed back to the handler.
Call this function after XblInitialize. If the library isn’t initialized or handler is null, the function returns 0 and doesn’t register a handler.To unregister the handler, pass the returned token to XblRemoveServiceCallRoutedHandler.