The IVR module contains models associated with recording the path a contact takes through an IVR call. Note that most of the logic used during IVR calls is still centralized in the flows module.
The IVRCall model represents an incoming or outgoing IVR call. This is used as a way of grouping the individual IVRActions that took place on the call as well as track the external id of the call as stored by the VOIP provider.
The IVRAction model primarily exists in order to track individual steps through a flow and properly deduct credits against a TopUp.