This object is used to index one or more IECs in the
context of a single call. In most cases there will
only be one IEC when a call fails. However, it is
possible for the software processing the call to
generate multiple IECs before the call ultimately fails.
In that scenario, there will be multiple entries in
this table related to a single call (cCallHistoryIndex)
and this object will serve to uniquely identify each IEC.