Thought of one solution, if you are willing to do some configuration: This is at Cell. Schedule an msend based event with status blackout sending action so that event is sent to Cell a service/CI that you want to Blackout. The Alias formula, conditions and alias should match on that msend event for the CI you want to blackout so thatevent with blackout status gets associated with that Service.
And also schedule to send another the same event but with right status to release blackout.
(Or a alias id slots can contain directly the service ID, to avoid the alias formuila