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VoLTE: Why I-CSCF and S-CSCF has interface with the HSS and for what purposes it is used ?

+4 votes
VoLTE: Why I-CSCF and S-CSCF has interface with the HSS and for what purposes it is used ?
posted Aug 5, 2016 by Ganesh

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2 Answers

+1 vote

In the IMS network, there are multiple call session control function nodes present and each of the nodes has different functions to perform.
I-CSCF (Interrogating-Call Session Control Function) receives SIP message from the UE and check for the authorization of UE by fetching profile from HSS and also to find out the correct S-CSCF so that it can forward the received SIP message to selected S-CSCF.

S-CSCF needs to do Multimedia Authorization what UE has requested. Based on the downloaded profile, S-CSCF takes decision to proceed further or reject the registration.

In short, I-CSCF uses interface to HSS link to find the relevant S-CSCF for the incoming request and user authorization. S-CSCF uses interface to HSS to check what multimedia related features server supports and also authentication vectors to authenticate the UE.

answer Aug 7, 2016 by Harshita
Thanks Harshita
0 votes

I-CSCF talks to HSS to get UAR (user Authorization Request) and UAR (User Authorization response) via Diameter protocol, basically asking which S-CSCF to be used and it is capabilities, and forward the request to that particular S-CSCF address, one S-CSCF get the request it needs to talk to HSS for Multi Media Authentication request and answer before it respond back to UE.

as my understanding

answer Sep 7, 2016 by Yaser Mohammed
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