Boundary intermediate timer events can be interrupting or non-interrupting depending on the activity type. The supported types are described in About Interrupting Behavior for Boundary Intermediate Events.

You can configure the interrupting behavior with the Allow Boundary Timer Event to interrupt activity check box on the General page in the Properties view, except as noted in the supported event types table referenced above.

Non-configurable interrupting behavior provides consistency with the timeout transition behavior of a non-BPMN referenced process step. For example, it is possible for a call activity to follow its timeout transition and to also follow the default transition, as the boundary intermediate timer event does not interrupt.