A user who wants to follow a call made by or to a specific entity (typically a person) sends a request to be notified when the entity makes or receives a call. The call is an audio or video call. The call can be based on a specific subject that the user has identified. When the entity makes or receives a call, a call processor detects that the call has been made. In response to the call, a notification is sent to the user. If the user has defined a subject, the system determines if the call is on the subject. If the call is on the subject, the notification is sent. If the call is not on the subject, the notification is not sent.