Fulfillment Status Callback — Reports fulfillment progress back to the systems and people waiting on it — CRM, the order record, the customer. Orchestration emits the events, and conditional billing activation listens for the completion signal it carries.
Fulfillment Status Callback lives in the Fulfill & Activate phase of Fulfill & Bill — the stage where you activate what was sold, meter what's used, bill it right. In the corpus tool index this phase maps to the Entitlements and Billingcategories.