# Receiving NMS OAM alert notifications

To receive NMS OAM events from a resource host, a client application must register with the Supervisor on the resource host to receive alert notification messages. An application registered on a given resource host receives all NMS OAM-generated events for all applications registered with that host, regardless of which client application triggered which event. These events include board-level tracing information.

A client application registers for alert notification using oamAlertRegister. With this function invocation, the client application passes the handle to the NMS OAM service. The application is immediately registered for alert notification. The application must register separately with each resource host to receive events from that host.

To unregister from alert notifications, a client application uses oamAlertUnregister. Pass the handle to the NMS OAM service when invoking this function. The application is immediately unregistered.

Note: Rather than unregistering, a registered client application can use ctaSetEventSources to mask out NMS OAM events. For more information, refer to the Natural Access Developer's Reference Manual.