SystemObject
  SystemEventArgs
    Avaya.ClientServicesCallPreemptedEventArgs

public class CallPreemptedEventArgs : EventArgs

Sent to inform application about call being preempted. any other new call while tone is being played. This would trigger application to start either continuous preemption tone OR three seconds preemption tone based on flag isPreemptionCompletionRequiredByClient and call state. Call preemption occurs when a precedence call is sent to a preemptable endpoint that is busy with a call of lower precedence and has no idle appearances. This causes the lower precedence call to be preempted, regardless of whether the lower precedence call and the new higher precedence call are of the same media type. When preemption occurs, the active busy user receive a continuous preemption tone until user acknowledges the preemption by invoking complete preemption method and the other party receives a preemption tone for a minimum of 3 seconds. After acknowledging the preemption, the extension to which the precedence call is directed will precedence tone. Application must start playing preemption tone upon receipt of event Preempted and stop preemption tone before calling CompleteCallPreemption when user acknowledges the preemption. However when other end receives preemption application must stop tone after 3 seconds and CompleteCallPreemption is NOT needed since there is no precedence call is directed at this end, other end is free and ready to receive