The Cancel is issued by the ICM to cancel a previously-requested operation that is identified by its InvokeID.
The RequestID must match the InvokeID of the request that is to be canceled.
If they match and the operation is canceled, a Dialogue_Failure_Conf_Send with a status of E_OPERATION_CANCELLED must be sent.
If they match and the operation cannot be canceled, a Dialogue_Failure_Conf_Send with a status of E_OPERATION_NOT_CANCELLED must be sent.
If the IDs do not match, or the ID is no longer active, a Dialogue_Failure_Conf_Send with a status of E_INVALID_INVOKEID must be sent.