header questions

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jsmith2k1
Posts: 14
Joined: Wed Feb 29, 2012 9:48 pm

header questions

Post by jsmith2k1 » Thu Mar 29, 2012 6:05 am

I am interested in tracing a calls path of traversal through the internet. Any input would be appreciated.

How do I determine the Operating Company Number (OCN)?
(I am told it is 979E for the header below)

Where do I lookup the company name representing the OCN?
(I am told 979E represents Bandwidth.com)

What is Automatic Number Identification (ANI) and how do I determine it?
(Is this just a fancy way of saying calling telephone number?)

In the header below it looks like a call is coming from flowroute(216.115.69.xxx) to flowroute .
Why would ServePath (69.59.142.213) and Level3 (4.55.18.99) be in the path traced?

Did the call start at ServePath and end at Level3 or vice versa? Or some other path?
If the header does not contain what I seek, where do I find the information.

With much appreciation and Thanks,
Brent


If I have the following header:
-------------------------------------
Via: SIP/2.0/UDP 69.59.142.213:5060;branch=z9hG4bK69ff0bc31d91620752f9dd266ecd8be9eaf21148;rport=5060;received=69.59.142.213
Via: SIP/2.0/UDP 216.115.69.144;branch=z9hG4bKf57b.0f7afc436d3d7e40404094376332a8b6.0;received=216.115.69.144;rport=5060
Via: SIP/2.0/UDP 216.115.69.131;branch=z9hG4bKf57b.e03b2547cbc347f111b0b4099e4473b0.0
Via: SIP/2.0/UDP 216.115.69.132;branch=z9hG4bKf57b.c64e4af322e2565bc79ba57e49314686.0
Via: SIP/2.0/UDP 4.55.18.99:5060;branch=z9hG4bK04B418c01cc8a29fbad
To: <sip:+1855235XXXX@flowroute.com>
From: <sip:+1954366XXXX@flowroute.com>;tag=gK04203bf2
Call-ID: 1308943784_83002604@4.55.18.99
CSeq: 26079 INVITE
Contact: <sip:+1954366XXXX@4.55.18.99:5060>
Max-Forwards: 65
Record-Route: <sip:216.115.69.144;lr>,<sip:216.115.69.132;lr>
Accept: application/sdp, application/isup, application/dtmf, application/dtmf-relay, multipart/mixed
Content-Length: 228
Content-Type: application/sdp
Proxy-ReceivedFrom: udp:216.115.69.144:5060
Proxy-ReceivedOn: udp:69.59.142.213:5060
P-Asserted-Identity: <sip:+1954366XXXX@flowroute.com>

Aaron
Site Admin
Posts: 4652
Joined: Thu Jul 12, 2007 12:13 am

Re: header questions

Post by Aaron » Thu Mar 29, 2012 10:10 am

No idea what the OCN is, I suspect it's a US term for the originating telco or similar. If so a SIP header is unlikely to allow you to determine that since it will be generated by a SIP-to-PSTN gateway provider rather than the telco that owns the PSTN infrastructure.

The PSTN caller ID, which is what ANI will normally use, equivalent in SIP is usually the From header, in your example "From: <sip:+1954366XXXX@flowroute.com>;tag=gK04203bf2" so the PSTN equivalent caller ID would be 1954366XXXX. The P-Asserted-Identity is another way to represent caller I but is not that common.

Apart from that the Via headers track the SIP proxies that a request has travelled through so can give you an indication of the network path it has traversed. Some providers will have multiple SIP Proxy like servers on their network so a request could travel through multiple servers located at a single provider and that seems to be the case in your example.

jsmith2k1
Posts: 14
Joined: Wed Feb 29, 2012 9:48 pm

Re: header questions

Post by jsmith2k1 » Thu Mar 29, 2012 5:04 pm

Aaron,
Thanks for the info. I admire your sipsorcery!

How do I interpret the Via headers to a network path traveled?
In this example the origin caller is 1954366XXXX@flowroute.com.
What Via header corresponds to the origin? Which is next?

If ServePath (69.59.142.213) is sipsorcery, then reading backwards Level3 is the origin, but the caller's number is flowroute. And why does flowroute say the call is coming to them from Bandwith.com? (Was that just a mistake). I am so confused. Can you point me to a good reference?

Thanks,
Brent

Aaron
Site Admin
Posts: 4652
Joined: Thu Jul 12, 2007 12:13 am

Re: header questions

Post by Aaron » Fri Mar 30, 2012 10:45 am

The Via headers represent the traversed SIP proxies with the top Via header being the last one, i.e. closest, and the bottom one the initial. So your SIP network path was:

Start: 4.55.18.99 -> 216.115.69.132 -> 216.115.69.131 -> 216.115.69.144 -> 69.59.142.213 (sipsorcery).

Flowroute could very well be utilising one of their PSTN provider's gateways which I guess could be what the 4.55.18.99. Normally a provider would obscure where a call comes from if it's not their own network by using a B2BUA instead of a proxy but there is no reason to do so apart from being obscure.

The best reference is the SIP RFC 3261 http://tools.ietf.org/html/rfc3261 it describes Via headers, SIP proxies and how SIP requests can be routed.

jsmith2k1
Posts: 14
Joined: Wed Feb 29, 2012 9:48 pm

Re: header questions

Post by jsmith2k1 » Fri Mar 30, 2012 3:58 pm

Aaron,
Thanks for the help. Will try to stand on my own feet now.

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