[openss7] [General SS7 question] -- OPC and DPC concept.

["Patrick Lam" <plam@encc.com>]

Hi:

This is a general SS7 question.  I think these are very basic SS7
concepts, but somehow I am just a little confused with the OPC, DPC and
CIC concepts.

1.  Do the OPC and DPC represent the point codes of the Calling End
Office and Called End Office specifically (i.e. the OPC and DPC are
constant within the whole switched path of a call, and is significant
all the way from the calling EO to the called EO)?
Or do they just represent the point codes of two adjacent  switches
exchanging messages (e.g. an Access Tandem and an IXC)  (i.e. the OPC
and DPC keep changing along the switched path, and is only significant
for 2 adjacent switches)?

2.  Similar question for CIC:  Is the CIC (Circuit Identification Code)
constant (and significant) throughout the whole switched path of a
call?  Or is it only significant between two switches (i.e. keep
changing whenever it "step by" a switch)?

Thanks very much in advance,

Patrick.