How do I use Beamable Notifications to asynchronously send information from server to client?

Normally when I invoke C# Microservice ClientCallable methods, the way that the server gives information back to the client is by way of the return value from the ClientCallable. What if I have "fire and forget" logic that is meant to run longer than the request/response pattern of a usual ClientCallable invocation? Is there a way to send server-to-client information "out of band"?