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Prepaid VoIP call with SIP phone on unknown fixed telephone number. You have addresses of HSS, SBC, SIP client, P-CSCF, SIP Application Server, S-CSCF and MGC. How to determine which number is called, for which requests and/or answers should I need to look for?


asked 02 May '11, 13:01

wired's gravatar image

accept rate: 9%

Maybe code 180 Ringing?

(02 May '11, 13:02) wired

Could the RTP traffic be a stiching point? RTP traffic runs after VoIP connection is establised. So I filted out RTP traffic and there are only two IP addressed - first belongs to SIP phone client and the second could to called part (B)?

(02 May '11, 16:27) wired

Hi, Are you asking how to find the E164 adderss of the called party, the IP addresses of the involved nodes to set up a call to that number is of no consequence in that case. Media(RTP) and signaling paths are separated so the RTP IP addresses will be different from call signaling. Media path will be something like Client(IP1) --- MediProxy(IP2) MediaProxy(IP3) --- MediGAteway(IP4)MediaGateway)TDM circuit ->PSTN The to header of the INVITE from the client might contain a tel URI or a phone context, containing the called party number. Regards Anders

(02 May '11, 21:49) Anders ♦

But the system could also use DNS to do translation from SIP URI to E164. Anders

(02 May '11, 21:49) Anders ♦

Actually I'm not sure what to expect. But as You said, INVITE header may contain a telephone URI/phone context with called party number.

Now I also sent this trace to my other cooworker who'll try to determine what's a called party number.

For now, thanks. :)

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answered 03 May '11, 03:31

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question asked: 02 May '11, 13:01

question was seen: 2,790 times

last updated: 03 May '11, 03:31

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