Ooma needs a Do Not Disturb (DND) feature code. If someone is in their office in a meeting, they can dial the feature code to turn on DND and the call will not ring on their set but follow the flow to the next point. That point may be voice mail or a receptionist. The system has the ability to designate the next point for the call to go, but nothing to make the call go there immediately.
An extension in a ring group that has DND enabled will be skipped and the next extension in the ring group (if any) is rung.