[SIPForum-discussion] (no subject)

Deepanshu deepanshu at huawei.com
Tue Jun 19 03:28:47 UTC 2007


The I-CSCF function can be removed from the signalling path once it has been used to establish which S-CSCF is in use. But if the THIG functionality is used in I-CSCF then it MUST remain in the signalling path (for encryption and decryption purpose).

So in your scenario. The call flow will be like:

UE1 ---> P-CSCF ---> S-CSCF ----> I-CSCF ----> S-CSCF ----> UE2

The Serving-CSCF handling session origination performs an analysis of the destination address, and determines that it belongs to a subscriber of the same operator. The request is therefore forwarded to a local I-CSCF. The I-CSCF queries the HSS for current location information, and finds the user either located in the home service area, or roaming. The I-CSCF therefore forwards the request to the S-CSCF serving the destination user

HTH

Deepanshu Gautam
R&D Engineer
Huawei Technologies Co Ltd.
91, BaiXia Rd, Nanjing, PRC
  ----- Original Message ----- 
  From: Deepak Innaini 
  To: Deepanshu 
  Sent: Monday, June 18, 2007 6:24 PM
  Subject: RE: [SIPForum-discussion] (no subject)


  Thanks deepanshu,

                        I have one more query for you......

  Suppose UA1 and UA2 are served by same S-CSCF and THIG functionality is implemented in I-CSCF.......so while UA'S getting registered in 200 OK response will contain 

  SERVICE ROUTE = ICSCF AND SCSCF ADDRESS
  PATH = ICSCF AND PCSCF ADDRESS

  So when UA1 had sent invite to UA2 and invite has reached S-CSCF.........we know that in IMS a call will be terminated on UA2 by checking the PATH header which he receives in 200 OK response for REGISTER message......my query is whether S-CSCF will route the call to UA2 via I-CSCF, P-CSCF.......or directly to P-CSCF......

  Can you tell me the call flow in this scenario..

  With regards   

  Deepak Innani  | IMS (Testing) | Tech Mahindra 
  9/7, Hosur road, Bangalore-560029. 
  Office:  91-80-41159800 |  Extn:1240  | Cell: 9901483038  
  Email: innanid at techmahindra.com 
  www.techmahindra.com 


------------------------------------------------------------------------------
  From: Deepanshu [mailto:deepanshu at huawei.com]
  Sent: Mon 6/18/2007 3:32 PM
  To: Deepak Innaini
  Subject: Re: [SIPForum-discussion] (no subject)


  When S-CSCF perform a DNS query it will get the address of itself (or i can say S-CSCF will not do DNS  query at all bcause it can recognize B as being served by itself), so it will send the request directly to B.

  I-CSCF only comes into picture when B is being served by different S-CSCF

  For it very clear, no confusion
    ----- Original Message ----- 
    From: Deepak Innaini 
    To: Deepanshu 
    Sent: Monday, June 18, 2007 5:53 PM
    Subject: RE: [SIPForum-discussion] (no subject)


    Hi deepanshu,

                     Can you give me the reason why it does not to I-CSCF..........i too had the same idea but somebody told me that it will go through I-CSCF so i was little bit confused.......

    Deepak Innani  | IMS (Testing) | Tech Mahindra 
    9/7, Hosur road, Bangalore-560029. 
    Office:  91-80-41159800 |  Extn:1240  | Cell: 9901483038  
    Email: innanid at techmahindra.com 
    www.techmahindra.com 


----------------------------------------------------------------------------
    From: Deepanshu
    Sent: Mon 6/18/2007 3:12 PM
    To: Deepak Innaini
    Cc: discussion at sipforum.org
    Subject: Re: [SIPForum-discussion] (no subject)


    No
      ----- Original Message ----- 
      From: Deepak Innaini 
      To: discussion at sipforum.org 
      Sent: Monday, June 18, 2007 3:23 PM
      Subject: [SIPForum-discussion] (no subject)


      Hi ,

                      In IMS when UA1 and UA2 are served by same S-CSCF(originating and terminating S-CSCF are same) whether an INVITE message passes through I-CSCF ????????????

                     UA1 registered to S-CSCF.

                     UA2 registered to S-CSCF.

      Deepak Innani.





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