This Annex describes the Subscribe/Notify framework to support event monitoring in the IMS architecture. The framework enables third party AF and network functions to subscribe to IMS DC events. IMS event exposure for event monitoring allows a consumer (e.g. a DC AS) to subscribe to and being notified about subscriber specific and non-subscriber specific IMS events and to invoke IMS services exposed by the IMS network via the NEF. A non-subscriber specific event monitoring request does not contain any target subscriber. Non-subscriber specific event monitoring requests are sent by the NEF directly to all IMS AS instances which support monitoring of the requested IMS event. The NEF may be configured with available IMS AS instances, or the NEF can discover IMS AS instances via NRF. A subscriber specific event monitoring request includes the targeted subscribers. The targeted subscribers can be either one distinct subscriber or multiple subscribers indicated by their IMS public user identities. The events in the subscriber specific event monitoring request are common to all targeted subscribers. The NEF sends one event subscription request per targeted subscriber to the HSS serving the given subscriber. The NEF may determine the serving HSS based on configuration or based on HSS discovery as depicted in clause AA.3.3. Once an IMS subscriber successfully registers in IMS and one of the IMS AS is assigned to the subscriber, the IMS AS which supports monitoring of IMS events registers its address in the HSS. For subscriber specific event monitoring requests received from the AF (e.g. DC AS), the NEF uses Nhss_ImsEE service to manage the subscription requests (e.g. subscribe/unsubscribe) via HSS. HSS uses Nimsas_ImsEE service to manage the subscriber specific subscription requests with the IMS AS assigned to the subscriber.