A Call Event is one of the standard UML elements that are supported by Cameo Simulation Toolkit. A Call Event of an operation is triggered whenever you call the operation. You can use CallEvents on AcceptEventActions (the first figure) and Transitions (the second figure). The first figure shows the Event Type: Call Event applied to the Accept Event Action.
Figure 1: An activity diagram showing a Call Event.
Figure 2: A state machine diagram showing how a CallEvent is triggered.