Download Multi-Protocol Correlation: Data Record Analyses and Correlator

CHAPTER 3. PROPOSED SOLUTION
the fact that we do not necessarily know which number is the international number;
it can even be more than one number. So to solve this we need to either just
compare and say that we allow some slack. This makes it a little uncertain and
prone to failure, but statistically the chance is very low. The other solution would
be to look up in a database and see what the number would be with and without a
international number. This adds additional intelligence, and makes the correlation
slow because it needs to check a database each and every time. With that problem
solved, all we need to do is to compare the ISUP CdPN with the SIP CdPN and do
the same for CPN if present. It will also be useful to make sure that the timestamps
are not too different. They need to be within at least x seconds of each other, with
x being a user specified parameter, a good default number is one. That should be
all we need to correlate SIP and ISUP calls, the results of our test can be found in
the result chapter.
Figure 3.7: SIP - ISUP call flow. Note that Megaco or MGCP is left out in order to
simplify it.
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