Vijay, there is some difference in terminating calls and incoming calls.
Terminating calls are those which terminate to your subscriber, the origination could be from your bsc , poi, vms etc. and
Incoming calls = Terminating calls – calls originated from your subscribers.
SO originating calls are those which originates from your BSS part only.
and Incoming calls = POI incoming + VMS incoming + any other outside source + transit calls.