Call Flows This section describes the following call flows. Counter Subscription/Retrieval (N28 Session Creation) Unsubscribe Counters (N28 Session Termination) N28 Counter-Based Policy Notification of Counter Changes from CHF Counter Subscription/Retrieval (N28 Session Creation)Unsubscribe Counters (N28 Session Termination)N28 Counter-Based PolicyNotification of Counter Changes from CHF